KEYNOTES INTERNATIONAL SYMPOSIUM polders of theworl d

Lelystad - The Netherlands - 1982

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CONTENTS

INTRODUCTION TOPOLDER S OFTH EWORL D 7

- W.A. Segeren.

LANDAN DWATE RMANAGEMEN T 15

- E. Schultz. Fromnatura l toreclaime d land.Lan dan d watermanagemen t inth epolder s of theNetherland s 17

- K. Praniah. Land andwate rmanagemen t inpolder s 43

CONSTRUCTIONASPECT S 55

- P.C. Mazure. Thedevelopmen t of theDutc hpolde r dikes 57 - R. Segevs. Fromwindmil l towind-generator .Developmen t inpolde r construction 75 - M.A. Meyer. Construction aspectso fpolder s inth e world 91 AGRICULTURALASPECT S 119

- J.V.d. Veen. Agricultural aspects inpolde r areasi n theNetherland s 121 - H. Bvammer. Agriculture and food production inpolde r areas '37

SOCIO-ECONOMICAN D PHYSICALPLANNIN GASPECT S '63

- A.K. Constandse. From spontaneous settlement to integrated planning and development '65 - J.H.M. Kienhuis. Themanagemen t ofpolder s inth e Netherlands 175 - A. Sfeiv-Younis. Economic aspects of soil conservation programs inLDC' s 187

EiftLiOi i.•'.-.;' RIJKSINSTITUUT VOORNATUUFtBB-*F£* 2 - 3POSTBÜS9201 6800H 3 ARNHEM-NEDERLAND ENVIRONMENTAL ASPECTS 221

- J. de Jong and A.J. Wiggers.Poldersan dthei r environment inth eNetherland s 223 - M. Vannuaai. Ecological valueso fpotentia l polderarea s 245

SPECIAL KEYNOTES 255

- A. Volker. Lessons fromth ehistor yo f impolderingi nth eworl d 257 - B. Verhoeven. Polderso fth efutur e 275

-4 INTRODUCTION TOPOLDER S OFTH EWORL D

W.A. Segeren.

5-

INTRODUCTION TOPOLDER SO FTH EWORL D Prof.ir.W.A .Segere n Professor inPolde r Development,Delf tUniversit y of Technology,Departmen to fCivi lEngineering ; Deputy-Director ofth eGovernmen t Service forLan d andWate r Use.

Owingt ohe r situationHollan dha sacquire d alo to fexperienc ewit h polders throughoutth ecenturies .Th eare awher e theDutc h arelivin g hasbee nadapte db ythemselve s toth edemand smad eb ya populou san d prosperous country,suc ha ssafety ,spac e tolive ,t owor k andfo r recreation, facilities forth eproductio n of food andth epreservatio n ofnature .Th eexperience ,gaine db yth eDutc h inthi s fieldrejoice s ina larg e international interest.Thi sexperienc e isuse d indifferen t ways inman yothe rcountries .Considerin g thepossibilitie s andth e necessity toemplo y theDutc hexperienc ewit hdesign ,constructio n andmanagemen to fpolder selsewher e inth eworld ,i ti si n factself - evidenttha tth eintentio n toorganis e aninternationa l Symposiuman d Exhibition aboutpolder s inth eworl ddevelope d inth eNetherlands . 1982seeme d especially suitablebecaus e several interesting eventsan d anniversaries takeplac e inthi syear .Mos to fthe mar ealread y well-knownan dhav ebee ncommemorate d witha lo to fpublicit ybu t inthi sconnectio n somewil lye tb ementioned . OnMa y 28,fift yyear sago ,th eAfsluitdij k wasclose d and thisyea r interesting eventsar etakin gplac ewit hregar d toth eOosterschelde - damb yplacin g the6 6columns . Especiallywit hrespec tt oth eIJsselmeerpolder s the fortieth anni­ versaryo fth eNoordoostpolde r andth etwenty-fift h anniversaryo f Oostelijk Flevoland canb ementioned . Moreover,twenty-fiv eyear sag oth eInternationa l Institute for Hydraulic andEnvironmenta lEngineerin g has started international educationo nwate r control.Thi scours eha sbee nattende d byman y engineers fromal love r theworl d andgive splent yo fattentio n toth e lay-outan dmanagemen to f low-lying,fla tpolder-lan d withregar d to watermanagement. FinallyTN Oexist s fiftyyear si n 1982.Thi sorganisatio no npractica l andapplie d researchha salway sha dplent yo f interest inth eman y aspectso f livingan dworkin gi npolder-lan d inth eNetherlands .

Aims

Threeaim sar ebein gpursue dwit h theSymposiu m andExhibition : 1.Th eexchang eo fknowledg e andexperienc eo npolder so n international level,t opolicy-maker s andengineers ,scientists ,managers ,builder s andpolitician salike .Fo r thispurpos e circularswit ha "Callfo r papers"wer esen tal love r theworld .Th erespon swa soverwhelming ; after selectionb ya scientifi c committee,som e 150paper swit h subjects alli nth e fieldo fpolders ,hav ebee nprinted . Manypaper shav ebee nreceive do ncertai npolder-area s;a tth e sametim e therewa sa larg e interesti npaper so n landan dwate rmanagement .Man y papershav eals obee nreceive d forth eothe r themesb ywhic h itha st o benote dtha tth econtribution s on socio-economic aspects andphysica l planningan denvironmenta l aspects aremainl y ofDutc horigi ni n contrastwit h theothe r contributions fromal love rth eworld . Theexchang e ofknowledg e andexperienc ewil lhav e totak eplac e especially during the Symposium. Some 400participant s from6 0countrie shav eapplie d forth e Symposium. The fulfilmento fthi sai mwill ,a tan yrate ,no tdepen do nth enumbe r ofparticipant s andth ecountrie spresent . 2.T ooffe r thepossibilit y toth eDutc h tradean d industry tosho whe r knowledge toth eassemble dpolder-expert so fth eworl dbot hdurin g theSymposium ,b ymean so fth epaper s alreadymentioned ,an da tth e Exhibition,b ymean so fstand sshowin g informationo nthei rtrade . About 40firms ,institute s and serviceswil lus e thispossibility .A sa framework forth eactivitie so fth eExhibition-participant s the organisationha smad ea separat eexpositio n showingth evariou s aspects ofplannin gan d constructing apolde r indifferen t countries,eac hwit h theirow npeople' s nature,prosperity-level ,natur eo fth e soil,climat e and such-like.Thi sexpositio n isals odivide d inth eSymposiu m themes.I tha sbee nbuil t insuc ha wa y thati tca nb euse d inwhol e or inpar ta sa framework fora nexpositio n abroadwher eDutc htrad e and industrywis h topresen t themselves.I nthi swa yth eai m- t o advertise theDutc h tradean d industryabroa d -ca nb e continued after theSymposium . 3.T osho wth eDutc hpeopl e inwhic hwa yothe r countrieshav ebee n dealingwit h the samecircumstances ,hopin gt ogai nmor e understanding forth ewa yw e livei nou row ncountry .Tha ti swh yman yactivities , interesting forth eDutc hpublic ,ar eorganise d allroun dth e Symposium andExhibition .Th eMinistr y ofTranspor tan dPubli cWork s hasissue da brochur e entitled "Polderso fth eWorld". 'I nthi s brochureman ydata ,collecte db y theSymposiu m organisation,hav ebee n reproduced easily accessible.Man yDutc han d foreign technical journals,paper san dothe rmedi apa y attention toth eSymposium . Spontaneously exhibitionso fpainting san dceramics ,it ssubject s inspiredb ypolders ,wil lb ehel d inLelysta d from4 til l 10October . Andmoreover ,a fe wday sth eexhibitio nwil lb eopene d forth epublic . TheExhibitio n aswel la sth eSymposiu mwil lb ehel di n the"Agora " inLelystad .Lelysta d actsalread y asa centr e forth eIJsselmeer - poldersan dwil lbecom e thecapita lo fth ene wpolder-province .

Themeanin go fpolder s toth eworl d

Thedescriptio n ofth emeanin go fpolder s toth eworl dha s tob e preceded firstb ya definitio no fwha ti smean tb y"polders" . Inparticula rprof.ir .A .Volke r givessom ethought s tothi si nth e serieso farticle s followinghereafter .Th e starting-point isth e followingdefinition : "Apolde r isa leve lare awhic hha soriginall y been subject,permanentl y orseasonally ,t oa hig hwate r level (groundwater or surfacewater )an d isseparate d fromth esurroundin ghydrologica lregime ,t ob eabl et o controlth ewate r levelsi nth epolde r (groundwater and surfacewater ) independently of thesurroundin g regime" .

Theseparatio n fromth e surroundinghydrologica l regime andth e water levelcontro l inth eare aar eth emos timportan t characteristics ofa polder .The yar enecessar y tob eabl et ous eth eare a ina wa y thatwa sno tpossibl e inth eorigina lcondition .Othe r important characteristics ofa polde r areth e flatsurfac e andth e facttha t almostneve rbig ,fo ragricultur e troublesome stones,ar e found inth e soil.Th ereaso n forthi sca nb e found inth eorigi no fa polder , thedepositio no fparticle s eroded elsewhere,b yrunnin go r stagnant water.Th eabove-mentione d definition andexplanatio n ofa polde rma y leadt oman ydifferen tinterpretations . For instance inthi swa ya paddy-fiel d isa polde r justa sth e flood- plaino fa larg erive rprotecte d from floodsb y anupstrea m damwit h areservoir . Ingenera lneithe ro fthes earea sar e indicatedwit h thewor dpolder . Anyway,i nth eframewor k of "Polderso fth eWorld " apractica l approach hasbee n chosen forth edelimitatio no fth esubject . For theSymposiu m thosearea sar etake na ssubjec twher e development necessitates the samepractice san dtechnique s asth eone suse di n polders.Leve ltopograph y andhig horigina lwate r levelsar e characteristics ofthat .

Inth e framework of theSymposiu m researchha sbee ndon eafte r areas where "polder know-how"i sessentia l for,especiall y agricultural, development.Th e International SoilMuseu m hasderived , fromth e FAO-UNESCOWorl d SoilMap ,th e fact that 1200millio nhectare s aret o be found in theworl d asa nabsolut emaximu mo f levelarea so fwhic h the soili sbein g influenced by groundwater or shows,b y itsprofile , regular flooding. These soilshav emainl y developed fromalluvia ldeposits .O f thisamoun t thepar twithou t growing season, 109millio nhectares ,ca nb e excluded atonce .Fro mth eremainin g 1100millio nhectare smor e thanhal f ist o be found inarea swhere ,a sfa ra sth e lengtho fth egrowin g season isconcerned , threecrop spe ryea r arepossible .Thes ear eth e tropical and subtropical regions.I tha sbee nassume d that enoughwate r for

-1 0- forplan tgrowt h isavailabl e inth e formo frainfal ,soi lmoistur eo r irrigation. Whenothe r criteriaar eused ,suc ha sbearin g capacity,germinatio n possibilities,natura l fertility,sal tcontent ,tillage ,rootin g capacity etc.anothe r 200millio nhectare s canb eexclude d asbein g notsuitable .O fth eremainin g area,som e 900millio nhectares ,th e suitability varies frommoderatel y suitable togood . Inth etabl ebelo wth edistributio n ofthes earea si sgive n forth e differentcontinents .Th enam e "potentialpolders "i suse dbecaus e polderknow-ho w isnecessar y forth edevelopmen t ofthos eareas .

Potentialpolder s in 10.000h ao r 100km 2. After:dat ao f theInternationa l SoilMuseum .

1 crop 2 crops 3 crops total

North-America 1695 2054 295 4044 MexicoCentr.Americ a - 200 1867 2067 South-America 605 2861 12079 15545 Europe 8278 503 8781 Africa - 3036 16161 19197 South-Asia 78 4597 5813 10488 Northan dCentr.Asi a 16458 5231 247 21936 South-EastAsi a - - 5296 5296 Australasia - 3151 1200 4351 Total 27114 21633 42958 91705

The tableclearl y showstha ti nal lpart so fth eworl d largearea sca n befoun d suitable foragriculture .Fro mth etabl e itcanno tb erea d whether thesearea sar ei n facti nproductio n and ifso ,whethe rth e production circumstances require furtherdevelopmen t ornot . Alsono tpresen ti nth etabl e is,a twha tcos texistin gagricultur e canb eimprove d andwha tbenefit s thiswil lyield .Als on oanalysi s hasbee nmad eo fth eregiona lnee d formor eo r improved agricultural lands,th eavailabilit y of skilled farmersan d the socialan deconomi c

11 circumstances thathav e tolea dt oth eoptimu mus eo fne wo r improved land.Finally ,ou rknowledg e ofth eeffec to necolog y ofne w impolderingo r improvemento fexistin gpolde r areas,a sindicate di n thetable ,i sonl y limited.

Wherepolderdevelopmen ti sreall yneede d isno tknow nprecisel ynow . Thisdoe sno talte r thefac ttha tth eareas ,i nth etabl eabove , clearlyshow stha tpolderdevelopmen t cancontribut e importantly toth e world food supply,especiall y whenbein greminde d ofth e facttha t ingenera lthes earea sten d tob e fertile.

Threecircumstance s canb e distinguished: 1.Densel ypopulate dpolde rareas ,mainl y inAsia ,Europe ,amon gwhic h theNetherlands ,part so fAfric aan d somearea si nNorth ,Centra lan d South-America.I nmos to fthes earea sth eus ean dadministratio n of thepolder s isfa rfro mbein goptimum . Improvemento fth efoo d production forth e localpopulatio n canonl yb eobtaine dwhe n starting fromintegrate d ruraldevelopment .No tonl y landan dwate r managementwil lhav e tob eadjuste d technically.A tth esam etim e more attention shouldb epai d toeducatio n andextensio n services, credit facilities,processin g and saleo fproducts .Onl ywit ha strongparticipatio n ofth e localpopulatio n thissor to frura l developmentplan shav ea chanc e tosucceed ,togethe rwit ha wis e adoption-pace andprojec tsize .

2.Sparsel ypopulate d potentialpolde r areas indensel y populated regions,mainl y inAsi aan dpart so fAfrica ,i nEurope ,amon gwhic h theNetherlands ,an d some areasi nNorth- ,Central -an dSouth - America. These sparselypopulate d areasar echaracterize d by theirinaccessi ­ bility. Ingenera l largescal e engineering workshav e tob ecarrie d outbefor e the land canb emad e suitable foragriculture .Th erecla ­ mationo fthes e areasi stake na than d forreliev eo fth eoverpopula ­ tioni nth eregio nan d forth eproductio n offood ,bot h forth eregio n and,eventually ,fo relsewher etoo .

12 Theengineerin gwork sar e largescale .Th eparcellin g ofth e landca n takeplac eo na smal l scaleb ygivin gou tth ereclaime d land tomany - small farmers.I ngenera lth eengineerin g and landdevelopmen tproject s ona larg e scalerequir e large investmentswhic h areofte npayabl ei n itselfbu tca nno tb eaccomplishe d becauseo fbudgetar y reasons.Th e result istha tconcession s aremad eo n safety and lay-outo fth e area.A tth echoic eo fus eo fth e limitedmean stw ocriteri a should havever yhig hpriority . Firstly,th einvestmen t inlarg e engineeringan d landdevelopmen t projectsha st ob e suchtha t lateron ,whe nadditiona lmean sar e available,furthe r lay-outca nembroide ro nwha tha salread ybee n constructed.Therefor e aclea rpictur e isneede do fth e finalstage . Secondly,reclamatio n hast ob e insuc ha stag ewhe n the farmerstarts , thath e cangro whi sfirs tcro pwithou tto ogrea ta risk .Therefor e much attention shouldb epai d toth einitia lreclamatio no fth eland . Agriculture,finance d oreve ncarrie d outb y thegovernmen twil lb e almostinevitabl e duringth e firstyears .I ndevelopin g thene ware a sufficientattentio nwil lhav e tob epai d toth eintegrate d approach forrura larea sa sgive nunde r 1.A tdeterminin g theplac ean dth e scaleo f theare at ob ereclaime d ecological factorsmus tpla ya distinctpart .

3.Sparsel ypopulate dpotentia lpolder-area s insparsel ypopulate d areas,mainl yt ob e found inCentral -an dSouth-America ,part so f Africaan dAustralia . Ingenera l largeengineerin g and land development projectshav e tob ecarrie d out.Th e aim forreclamatio n ofthes earea s hast ob ea contributio n toth eworl d foodproduction .Thi smean stha t thecos to freclamatio n andproductio nha st ob emad eu p forb yth e priceso fagricultura lproduct swhic hmeans ,i nthi scase ,th eworl d marketprices .S oth e costo freclamatio n andproductio nwil lhav et o be low.Thi s ispossibl e because inthes e sparselypopulate dareas , highdegree so fmechanisatio nwil lb e aimeda tanyway ,fo rth e reclamation activities aswel la s forth eagricultura l production itself.Her eals oth eplace ,th eexten tan dth e lay-outo fth e reclamationhav e tob e chosen insuc ha wa y thata maximu mo f ecological stability issafeguarded .Government ,consultin g engineers

13 and contractors inth eNetherland s havea lo to fexperienc ewit h theoveral ldevelopmen to fpolder-areas .Thi sexperienc ean dknowledg e issuc htha tthe yca ngiv ea n importantcontributio n toeac ho fth e three circumstancesmentioned .A tth e sametim e theycontribut e to employmenti nthei row ncountry .Th edevelopmen to f the firsttw o categorieswil lofte ntak eplac eo ninitiativ eo fan dconducte db y thegovernment so fth ecountrie swher eth epolder-area s are situated. Inth eareas ,mentione d under 3.,th eDutc h could take the initiative themselvesno tonl yb ymakin g knowledge and experience availablebu t alsob ytakin g careo ffinance .

Contentso fthi sedition .

Tohav e aclea rrevie wo fal ldifferen taspect so fpolder so fth e world adivisio n into fivetheme s forth eSymposiu m hasbee nchosen : 1.lan dan dwate rmanagemen t 2. construction 3.agricultur e 4.socio-economi c andphysica lplannin g 5.environment . Foreac ho f these themes twospeaker shav ebee n invited,on e from theNetherland s andon efro mabroad ,mainl yworkin g fora ninter ­ nationalorganisatio na sWorldbank ,UNESC Oan dFAO .Th einvite d speakers givea revie wo naspect so fpolder san dpotentia lpolder s inthei rtheme . Finally twoDutc hprofessors ,ir .A .Volke r anddr.ir .B .Verhoeven , whohav e spenta nimportan tpar to fthei r career inan daroun d polders of theworld ,wil lgiv ethei rvie wo nth epas tan d future ofpolders .

Iwis h toexpres s thehop e thatyo uwil lrea d thesekeynot e withpleasur e and thatyo uwil l geta clea r insighti nth edifferen t aspectso fexistin g and futurepolder so f theworld .

14 LANDAN DWATE RMANAGEMEN T

- E. Schultz. Fromnatura l toreclaime d land. Land andwate rmanagemen t inth epolder s ofth e Netherlands - K. Praniah. Land andwate rmanagemen t inpolder s

15 16 FROMNATURA LT ORECLAIME DLAN D Land-an dwate rmanagemen t inth e polders ofTh eNetherlands . E. Schultz IJsselmeerpolders DevelopmentAuthority , ScientificDivisio n Lelystad,Th eNetherlands .

Abstract

This articledeal swit h land andwate rmanagemen t inth epolder s of theNetherlands .I tstart swit h abrie f overview,o f thehistor yo f impoldering.Informatio n concerningmeteorological ,hydrologica l and geohydrological datai sgiven .Th e structure of thewate rmanagemen t systemi sdescribed . Some attentioni spai d tosoi lmanagement ,wa - tesqualit y aspects and themai nstructur e of thewate rmanagemen t in theNetherlands .Finall y someidea s aregive n for thefutur e oflan d andwate rmanagemen t in thepolder s ofth eNetherland s

1 Introduction

TheNetherland s isa lo wlying ,densel ypopulate d countryborderin g theNort h Sea.Th emajo rpar t ofth e country consists of lagoonan d delta typeareas .Th eDutc hhav emad e thisare ainhabitabl eb yrecla ­ mationan dprotectio nagains t thewater .Bu t for this creationo f their country theDutc hha d tofigh t during centuries against the water,comin g from theNort h Sea,fro m therivers ,fro mrainfall ,o r water from lakes andblow nove r theadjacen t landsdurin ggales .

This articlewil ldea lwit h thedifferen t aspectso f land andwate r management in thepolder s of theNetherlands .Firs t somedat aabou t

17 theNetherlands ,togethe rwit h some general information about the polderswil lb egiven .

Startingwit h thepas t and abrie f description of thevariou swork s andproject sb ywhic h theNetherland swa sdeveloped ,som eo f theas ­ pects thatgover n thepossibilitie s tomak epolders ,suc h as themete ­ orological,hydrological ,geologica l and geohydrological conditions, willb ediscussed . Based upon these conditions,adrainag e systeman d a good soilmanagemen thav e tob eestablishe d ina polder .Aspect s ofsystem ,lay-out ,desig nnorm s andmean swil lb ediscussed .Som e attentionwil lb epai d towate rqualit y aspects and toth emai n structure of thewate rmanagemen t inth eNetherlands .

Onbasi s of theexperienc e gained during centuries ofimpolderin g and recentdevelopment s in techniques andwa y of thinking,som e ideaswil l be given for thefutur e of land andwate rmanagemen t in theNetherlands .

2 TheNetherlands .

The land areao f theNetherland s is 3,400,000 ha.A s aresul t ofland - reclamation and subsidence abouton e third issituate dbelo wmea nse a level (figure 1).Th eNetherland s is aver y densely populated country, 2 varying from 190inhabitant spe rk m inth enorther npar t to91 5inha - 2 bitantspe rk m inth e low lyingwester npart .Th e cities andindus ­ trialarea s-8 %o f thearea -ar emainl y located in thewester npart . The agricultural lands- 71%o f theare a- aresprea d allove rth e country.Th e forests andnatur e reserves -9 % of theare a- ar eloca ­ tedpredominantl y onth erelativel ywe t soils in thewester nan d northernpar t and onth esand y soils in thedune s and inth eeaster n part. (CBS, 1981).

3 Polders,genera laspects .

Originally themajo rpar t of theNetherland s -som e 2,000,000 ha.- , consists of lagoon anddelt a type areas originating from thedelta' s Figure 1.Th e ground leveli n theNetherlands .

19 of theriver sRhine ,Meus e and Scheldt.Owin g to the transgressions and regressions of these aan d thedifferen t climatological conditions, the land areareduce d orextende d atregula rintervals .Regula rfloo ­ ding of theare aoccurre d owing tohig hwate r levels of theNort hSe a during gales and orowin g tohig h river floods.Th epeople ,mainl y fishermen andhunters ,live d onth erive rbank sunprotecte d against extremesituations .

As fara si sknown ,th emakin go fprotectio nwork sagains tth ewate rstarte d approximately inth ethir d centurybefor eChris twhe npeopl e inth e northernpar to f theNetherland s built artificialmound s toliv eon . In the first century therewas ,unde r theinfluenc e of the technical power ofth eRomans ,abeginnin g of theconstructio n of smalldam salon g therivers .Late r alsodam swer e constructed toconnec t thesevera l mounds.Thes edam s could resist theregula r floods andprotecte d the landsmor e or less against thewater ,bu t theywer eprobabl y too lowt o safeguard the landunde rextrem e conditions.Late r onth esyste mo fdam s gradually improved anddischarg e structures (sluices)wer emad e inth e dams.Larg e activities indik e constructiondurin g thesevent h and eighth centurymak ei treasonabl et osuppos etha ti nth eeight h century thefirs tpolder swer emade .Durin g thefollowin g centuries theprotec ­ tionagains t these aan d theriver s improved regularly.

Gradually fouraspect s inrelatio n toth e land-an dwate rmanagemen t became ofimportance ,namely : -b y damming off thevariou s connectionswit h thesea ,system so f canals and reservoirs forsuperfluou spolde rwate r- o rbriefl y canal systems -graduall y developed These systemshav ea relativelyhig hwate r level (+0.4 0 m.belo wmea nse a level).Th e polders andhighe r landsdrai n theirwate rint o thesesystems , throughwhic h thewate ri s then,transported toth ese aan ddis ­ charged during lowtid e (figure2) ; - owing tosubsidenc e of thereclaime d soils,larg earea sbecam e graduallybelo wmea n sealevel ; - therewer e alo to f lakes.Th e topsoi li n theadjacen t areasmain ­ lyconsist s ofpeat .Durin g gales thewate r of the lakes destroyed thebank s asa resul to fwhic h the lakesextended .

20 Therear e largepea tareas .Th epea tha sbee nuse d for fueldurin g centuries.B ydiggin g thepeat ,lake swer e created.

dunes

pumping old polders station new polder Schermer Beem ste r acnermer oeemsier n MarxermeeMarkermeer r n n Flevoland

Figure 2.Schem e of therelativ e levelsi n thepolders ,th esyste mo f canals and reservoirs forsuperfluou spolderwate r and these a

The improvement of thewindmill sb y theinventio n of therevolvin g cap made itpossibl e that fromth emiddl e of thesixteent h century lakes were drained.Thi swa s particularly sowhe ni n thebeginnin g ofth e seventeenth century itwa s discovered that toplac e severalwindmill s ina serie s (figure 3)larg e land reclamationwork s couldb eexecuted .

canal for superfluous —-^ polderwater

poldercanal middle basin

figure3 .Ro wo f threewindmill s topum p outpolde rwater .

21 In thebeginnin g of thenineteent h centurymos tpolder swer emade .Be ­ sides thewinnin g ofland s along the coast,ther ewer e twoarea s left forwhic hplan s lived toreclai m them.Th e first areawa s theHaarlemmer ­ meer,a lak e inth eneighbourhoo d ofAmsterdam .Thi s lakeha d grown from 9,000ha .i n 1250 to 17,000ha .i n 1800 (Ramaer, 1892).Durin g two centuriesplan sha dbee nmad e toreclai m theHaarlemmermeer .Non e ofth e planswer e realized untili nNovembe r of 1836a gal eble w thewate ru p toAmsterda m and anothergal e inDecembe rble w thewate rint oth e streets ofLeiden .Altogethe r 11,000h awer e flooded.I twa s thentha t the central government decided that the lakeha d tob ereclaimed .

Thesecon d areawa s theZuiderze e and as soona s thereclamatio n ofth e Haarlemmermeerha dbee nexecuted ,seriou splan s started toreclai m land inth eZuiderzee .A disaste rwa snecessar y togiv e thefina lpus h to startth eworks .O nJanuar y 13, 1916,a gal e caused floodingsi n thearea s around theZuiderzee .O n June 14,1918 ,th eac tt oconstruc t theenclosur e dam andreclai mpart s of theZuiderze e passedParlia ­ ment.Ther ewer e threereason smentione d for thedecision : - greaterprotectio n against flooding; - improvedwate rmanagement ; -th ewinnin g ofagricultura l land.

Uptillnow ,sixt yyear s later, 165,000ha .forme r seabotto mhav ebee n reclaimed (figureA) .Durin g theexecutio n of thework sne w ideas about the landus e inth epolder shav ebee ndeveloped . Soi n therecen tpol ­ ders,apar t from theus e for agriculturalpurposes ,lan d isals ouse d for townbuilding ,recreationa l areas andnatur ereserves .

Notprimaril y toreclai mne w land,bu t ofgrea timportanc e for thepro ­ tection against thesea,ar e themai ndelt awork s in thesout hwester n parto f theNetherlands .I nFebruar y 1953,i nthi sregio n 195.000ha . were flooded and almost 2000peopl edrowned .I n 1958th eDelt aAc twa s accepted,givin gwa y toth ebuildin g of large dams and otherhydrauli c contructions and theraisin g ofexistin g dikes along theNort h Seaan d themai n rivers.

22 Kampen •Dronten H ^/?

new towns # villages in the polders village projected o O villages on the old land Nijkerk -^— dike completed ,25 km __ dike projected

Figure A. The IJsselmeerpolders.

23 While thebi gproject s tookmuc h attention alo to fwork s in thepolder s were alsobein g carried out.Owin g tosubsidenc e and toimprove dnorm s regarding thewate rmanagement ,improvemen twork shav ebee n regularly executed.Sinc e 195Awhen ,th eLan dConsolidatio nAc twa s accepted, several land consolidation schemeshav ebee nexecuted . These schemeshav e thegoa l toredistribut e the landamon g thefarmers . Within the framework of these schemes,th ewate rmanagemen tha susuall y beenimprove d (Vande nHende , 1978).

The landi n thepolder swa snormall y used foragriculture .O n thehighe r parts thecitie s andvillage shav ebee n constructed.Th e growth ofth e population,especiall y after thesecon dworl dwar,mad ei tnecessar y to findne w locations forurba nareas .Becaus e allth ehighe r locations were already occupied,i tbecam enecessar y tohous e thepeopl ei nth e polders.Altogethe r about 7t o8 millio npeopl e areno w livingi n polders inth eNetherlands .

Thehistor y of landreclamationi nth eNetherland sha sresulte d inth e differentpolde rareas : - Low lying lands 1,335,000ha . - Drained lakes 315,000ha . - Landwo n from the 350,000ha . sea. Total 2,000,000ha .

Infigur e5 th earea s inth eNetherland s thatnee dprotectio n areindi ­ cated.

Butprotectin g low lying land against thewate r onlymake s sensewhe n such anundertakin g iseconomicall y justified.Thi smean s thatth e outputha s tosurmoun t theinput .Th e costs of thewate rmanagemen t system,likeinvestment s for constructions andexpense s formaintenance , areinfluence db y themeteorologica l situation- especiall y rainfall andevaporatio n- thegeologica l andgeohydrologica l conditions andth e degree ofwatercontro l thati srequired .Th e aspect thatar eo f importancewil lb e discussed.

24 UM«lmttrpold«rt Dtvttopmtnt Authority

GERMANY

area subject to flooding in the absence of sea dikes and dunes

area subject to flooding in the absence of river dikes frontier drained lakes sea dike

land gained on the sea '*l -f *•> dune

Figure5 .Area s inth eNetherland s protected againstflooding .

25 4 Meteorological aspects

TheNetherland sha s atemperat emaritim e climatewit h arathe reve n distribution ofrainfal love r theyear .Th emea n annualrainfal li s about 760mm .Th erat eo fevaporatio n fromope nwate rvarie s from 0mm/da y inwinte r to4 - 5 mm/da y insummer .Th emea nannua levapora ­ tioni sabou t 700m m (figure6) .

120 •' A s 100 \ \ • s rainfall / ^ \ \ \ 60 \ \ i t \ i \ i \ / \ / \ / s / / S __yy \ D month Figure6 .Mea nmonthl y rainfall andevaporatio n fromsurfac ewater . Rainfalldata :Hoofddor p 1867-1980. Evaporationdata :D eBil t1911-1980 . (RoyalMeteorologica l Service, 1867-1980)

Owing to therelativel y evendistributio n ofprecipitatio n overth e year, theintens epotentia lévapotranspiratio ndurin g summer andth e lowpotentia lévapotranspiratio ni nwinter ,ther ei sunde r averagecon ­ ditions arainfal ldefici t inth esumme rmonth s amounting to 120m man d a surplus ofrainfal l in thewinte r amounting toa naverag e of 300mm . Inrelatio n toth edesig no f thewate rmanagemen t system theshor t term rainfall intensity isimportan t (figure7) .

26 rainfall in mm

,"" y y 130 / * • 120

T=100 ,*À /" 4 100 y .y S * • / ,-'1 / .X / / / T=10 / y 80 t ' y" .--'

y .---•

* ,'" T=2 60 ,' / s'

X ,-"' y 40 \y

30

T = return p eriod in y aars winter p eriod summer period

10

9 10 days

Eigure 7.Rainfal l intensity-frequency curves. Hoofddorp,perio d 1867-1980.

27 Whilewindmill shav eplaye d aver y important rolei nth epumpin g dryo f polders,th edistributio no f thewin dvelocitie shas ,o f course,bee n ofimportanc etoo .

5. Hydrological aspects

The discharge ofwate r froma polde rha s tob erealize d ina mor eo r lessartificia lway .Fo r designing discharge structures likedischarg e sluices orpumpin g stations iti snecessar y tohav ebot h information about therainfal l surplus and about thepossibilitie s todischarg e thewater .Wate r canb edischarg eto : - anotherpolder ; - acana lsystem ; - ariver ; - thesea .

When apolde rdischarge s into anotherpolde ri ti snecessar y tochec k thecombinatio no fbot hmanagemen t systems.Th esam ehold s truewhe n apolde rdischarge s into acana lsystem .Th e typical aspects ofth e river regime,i ncombinatio nwit h thedesig nperiod s for thewate r management systemi nth epolder ,ar eimportan twhe n apolde r discharges into ariver .Th emai nriver s in theNetherland s normallyhav erelati ­ velyhig hwate r inspring .Suc h ars ei n levels cancontinu e forsevera l dayso rweeks .

When apolde r ora cana l systemdischarge s into these aon e canmak e useo f theadvantag e of the tide.Durin g lowtide ,sluice s canb e opened.Durin ghig h tide theyhav e tob e closed.Especiall y during spring and autumn,northwesterl ywind s cancaus erelativel y highwate r sealevel s during somedays .

6. Geohydrological aspects

Importantpart s of theNetherlands ,a sa resul to f land reclamationan d subsidence,ar enowaday s locatedbelo wmea n sea level (figure1) .

- 28- The geologicalprofil e in thelo wpar to f theNetherland s canb ebriefl y summarized asa holocen e toplayer consisting of clay and/orpea t anda thickpleistocen e layermainl y consisting ofsand .Th e thickness ofth e Holocene toplayer canb eu p to2 0m .

Due toth e locationbelo wmea n sea level therei sseepag e inth edeepe r polders.Normall y this seepage amounts toles s than 1mm/da ybu t there areexception so fu p to2 0mm/day .

In thewester npar to f theNetherlands ,a sa resul to ftransgression s and regressions,thegroundwate r isbrackisc h orsalin e so theseepag ewate r isofte nbrackish .Fo r thisreaso n thewate r inth ecana lsystem sha st o be flushed regularly.Fo r thispurpos e substantial quantities ofwate r areuse d from therive rRhin e and theIJsselmeer .Fo rexample ,i nth e westernpar to f theNetherlands,th eamoun to fwate ruse d during asumme r ft ^ period,partl y forsuppl y andpartl yfo foir flushing ,i sabou t 650x 10 m whichmean s 290m msprea d over thearea .

7 Watermanagemen t system

Originallyonl y farmers lived inth epolders .Mos t citieswer e located on thehighe rgroun d orwher e artificial landfillha dbee n applied.Th e water control system inth epolde rwa s therefore designed and constructed according tonorm s applicable for agricultural areas.Thi swa spredomi ­ nantly thesituatio nunti l thesecon dworl dwar .

After thesecon dworl dwa r intensive urbanscheme swer eexecute d in existingpolder s tohous e thepeopl ei nth eneighbourhoo d of thecities . Mostlyb y landfill theare awa s "depoldered" and drained directlyint o oneo f the canalsystems .Gradually ,fo rne wprojects ,th e landswer eonl y raised tosom e levelabov e thewate r level inth epolder .I nthes ecase s both thewate ro f therura l and theurba n areasha d tob epumpe dout . So thedesig nnorm s for thewate rmanagemen t systemha d tob eadapted .

29- Thewate rmanagemen t system inside aDutc hpolde r consists inprincipl e ofsom eo ral lo f thenex t items (figure8) . - sluice(s),windmill(s )o rpumpin g station(s); - canal(s); - mainditch(es) ; -ditches ; - openo r closed fielddrains .

Poldershav e tob eprotecte db y dikes against thewate rfro m outside.

Figure 8.Schemati c layouto f apolder .

Sluices,windmill s andpumpin g stations

Depending on therelatio no f thesurfac e levelan d the levelo fth e receivingwate rbody ,sluice s orpumpin g stationshav e tob einstalled . Inth e olderpolder s thedischarg e ofwate rwa smainl y achievedb ymean s ofsluices .Th e firstwindmil l for thedischarg e ofwate rwa s construc­ ted about 1400.Howeve rwindmill s onlybecam e commonpractic e afterth e invention of therevolvin g capan d introduction of theide ao fplacin g severalwindmill s ina ro w (figure 3).I n 1770th e firstapplicatio no f thestea mengin ewa s tested.Th eyear s thereafter steam engineswer ein -

30 stalled insom epolders ,bu t always incombinatio nwit hwindmills .I t took about eightyyear sbefor e apum p drivenb y astea mengin ewa s trus­ tedi n such awa y thati twa suse d as theonl y device topum p outth e water.Bu ton eo f the first applicationswa s atremendou s one,sinc e itwa s used topum p dry thepolde rHaarlemmermee r of 18,000h a (Huet, 1885).

Inth ebeginnin g of the twentieth century electrical and dieselpowe r wereintroduced .Thes esource s ofenerg y are,generall y speaking,th e only onesno wbein guse d in thepumpin g ofwate r frompolders .Figur e 9 shows the locationo fpumpin g stations used fordrainag e inth e Netherlands (Rijkswaterstaat).

Fora lon gperio d oftim eth epaddle-whee lwa s theonl ydivec eused .I t could raise thewate ru pabou t 2m . In themiddl e of the seventeenth century theope nArchimede s screwwa s introduced.Wit h thisdevic eth e water couldb e raised up about 4m . Inrecen t times thescre wpump , thescre w centrifugalpum p and thecentrifuga lpum phav ebee nused . They canrealiz e allnormall y occurringheights .

Drainage system

The layout of thesyste mo f openo r closed field drains,ditches ,mai n ditches and canals inpolders ,i smainl ybase d upon topography,soi l conditions ando nagricultura leconomy .Ove r thecenturie s thesize s of theplot shav ebee nenlarged . Infigur e 10som e representative systems ofparcellin g out aregiven .

Thewate r levelsi nth e canals aredetermine db y thedept h ofdrainag e required by thedifferen tuse s of land.I n theolde rpolder s theparcel ­ lingou ti softe nbase d on thenatura lpatter n ofstream s andcreeks . Inth epea tpolders ,th edraine d lakesan d othernewe rpolders ^th e ditches runalon g the long sides ofa plot ,th emai nditche s alongth e shortsid eo fa plot .

31 Figure 9.Pumpin g stations fordrainag e purposes inth eNetherlands . (Rijkswaterstaat).

32 PEAT POLDER

RIVER POLDER

HAARLEMMERMEER FLEVOLAND

Figure 10.System s ofparcellin gout .

- 33 Originally,th edesig n of thedrainag e systemha dbee nbase d ontria l and error,bu t from thethirtie sempirica l steady state formulas could be applied. In these formulas acertai nris e in thewate r leveli s combinedwit h anaccepte d frequency and adesig ndischarge .Wit h these formulas anadequat e design of thewate rmanagemen t systemi spossible . Nowadays,wit h theai d of thecomputers ,a mor e scientific approachi s possible.Thi s approachno tonl y leads toa nadequat e designbu tals o gives thedesigne r agoo d insight intorelevan talternatives .

Theplo tsize s inne wpolder s arebase d mainlyupo n agricultural economy.Figur e 11show s anexampl eo f thederivatio n ofoptima lplo t sizes.

costs per h a in 10 gi ilders parce size in ha

?R

?fi

?4

??

^ 50 ?n

60

1R

1fi

14

1?

10 500 600 800 900 1000 1200 1300 1400 1500 parcel length in m Figure 11.Analysi s tocalculat e optimalplo tsizes .

34 Field drains

Field drains are applied for twosuccessiv epurposes : - lowering of thegroundwater-tabl edurin g landreclamation; -maintainin g adequate drainage conditions afterreclamation .

For fielddrain s therear e twopossibilities : - trenches; - subsurfacedrains .

Trencheshav ebee nuse d over centuries.Subsurfac e drains datefro mth e nineteenth centurybu thav ebee nespeciall y applied since thesecon d world-war.Nowadays ,the y areusuall ymad e of corrugated plasticpipe .

The distancebetwee n thedrain s and theirdept hhav e tob e choseni n such awa y thatoptimu mgrowt ho f the crop canb e assured.Severa l drainage formulashav ebee ndevelope dt ob euse di nth evariou ssituations . When therecentl y reclaimed soilha s ahig hpor e space,subsidenc ewil l occur,particularl y in the top-layer.Th edrain shav e tob e installed at such adept h thatafte r subsidence thesoi li s stillwell-drained .

8 Soilmanagemen t

Originallymos t soils in thelo wpar t ofth eNetherland s contained brackisch groundwater.Th e soilwa s rather saline,especiall y inland s won from these aan d ina numbe r of thedraine d lakes.Whe n anadequat e drainage system isinstalled ,unde r theprevailin g climatological con­ ditions in theNetherlands ,th edesalinizatio n of the topsoil isrealize d within someyears .Tw oprocesse s contribute tothis ,namely : - thepermeabilit y of theunripene d deeper soils isnormall yver y low.Th epermeabilit y ofth eripene d top layeri srathe rhigh .Durin g winter therei sa rainfal lsurplu s sosalt s arewashe dout ; - themajo rpar to f theseepag e flows directly to theditche s and the canals,s oth eroo t zonei sno t affectedb y thisbrackis hwater .

35- Steps during thereclamatio n

Especially in thedraine d lakeswhe n thesoil s felt dry,the yar e unaerated and almost impermeable.I nth eol d reclamations thiscause d a loto fproblem s toth efirs t farmers that tried togro w theircrop s on thesesoils .

In thene wIJsselmeerpolders ,specia lmeasure s are taken tole tth e soils "ripen".Thes emeasure s consists ofdrainag emeasure s together witha nadapte d crop rotation scheme (figure 12).Wit htrenche s a first lowering of thegroundwate r tablei sestablishe d and crackfor ­ mation inth ecla y soils starts.Thes e cracks result ina nincreas e in permeability.Whe n aftersevera lyear s thegroundwate r table isdee p enough,th e trenches arereplace db y subsurface drains.Th e subsurface drains realise afurthe r lowering of thegroundwate r table.Becaus e the bearing capacity ofth esoil s during reclamation isver y low,onl y those crops- rap e seed and cereals- ar egrow nwher e thenecessar y cropping measureshav e totak eplac e duringperiod swit h anevaporatio nsurplus .

Besides thesevera lmeasure s takendurin g landreclamation,soi limprove ­ mentmeasure s sucha sdee pploughin g and subsoilinghav ebee ntaken , dependingupo n localconditions .

36 reed

1 year sss^ jÄssssssmsmss^^ JM^^ 0.60

I- rape seed 2. winter wheat 3. barley

2-3 years ssssssm R^^^^S^ fssssssssp^^^a ESSSSSSpssssss^s /w^p m

rape seed

1 year »S \ fj^^^^ 5 J^^^^^m i fSSSSSSm . p\wm**u pjx^\x

1.20 ^ | U

48.00 several kinds of crops

S^555^^^55^55^^^^^^55^^^^^^^^^—)^^5^^55^^^^^^^^555^55^55^^^^S^5^ ^ I /

Figure 12.Measure s takendurin g landreclamationi nth e IJsselmeerpolders

37- 9 Waterqualit y aspects

Over alon gperio d of timeon eo f themai n goals of thewate rmanagemen t systemwa s thepreventio n ofsalinization .Source s forsalinizatio nwer e createdby : - saltwate r intrusionb ysluices ; - saline orbrackis h seepage.

From themiddl e of thesixtie s oterwate rqualit y aspects gotmor e emphasis.Th ereaso nfo r thiswa s the changing useo f thewater ,fo r example forrecreatio n andnatur e reserves and theincreas e inproduc ­ tiono fdomesti c and industrialwast e and coolingwate rproblems .S o the control ofbot hwate rquantit y andqualit y came toth e forean d measuresha d tob e takent ocontro l thewate rqualit y suchas : - purificationplants ; - separate sewersystems ; - flushing of lakes or canalswit hwate rwit h arelativel y good quality.

10 Main structure of thewate rmanagemen t in theNetherland s

The situation of thewate r inth eNetherlands ,wit hproblem s ofsalini ­ zation andpollutio n on theon ehan d and onincreasin g demand for drinking,irrigation ,coolin g andprocessin gwate r onth eothe rmake s itnecessar y thatspecia l attentioni spai d toth emai nwate rstructure . Especially thedr y summer of 1976ha sencourage d theundertakin go f studies inrelatio n toth edistributio n ofwate r over theNetherlands . Anintensiv e studyname d "PolicyAnalysi s of theWate rmanagemen t in theNetherlands "wa smad eb yRijkswaterstaa t and theRan d Corporation (Blumental, 1982).Durin g this study,cos tbenefi t analyses ofsevera l development alternativeswer e checked.Th eresult s of this study creates a solidbas e for thefurthe r development of themai nwate r structure in theNetherlands .

38- 11 Evaluation andpossibilitie s for thefutur e

TheNetherlands ,a si ti snow ,i sth eresul t of ahistor y oflandreclama - tionan d the losso fland .Fo r thefutur e therear ei nprincipl e only a fewplace s in theNetherland swher epolder s canstil lb emade .Ther e are threeplace s forwhic hmor e or lessseriou splan shav ebee n developed: -Markerwaar d 41.000h a - Slufterplan 600h a - planWaterma n 2.000h a

More futuristicpossibilitie s canpossibl yb e found inth eNort hSea . However itha s tob ementione d thatpossibilitie s arerathe r limited while the levelo f thebotto mo f theNort h Seaha s such arapi d slope (figure 13). (Rijkswaterstaat).

For themaintainin g of theexistin g land theris eo fth ese a levelo f about 0,10 mpe r century and thesubsidenc e ofth e landwil l gradually lead toa nincreas e insalin e seepage and thenecessit y toincreas e the levelo f theto po f thedikes .

Regarding thedesig no f thewate rmanagemen t system the following developments canb e excepted.

The drainage systemi na polde r isno walmos t atit soptimum .Ther ei s agoo d insight into thebehaviou r of thesyste m and theextrem e situations that canb eexpected .B y furthermechanizatio n andautomati ­ zationo f the construction andmaintenanc e of thesystem ,i t canb e made and operated atminimu m costs.I na moder npolder ,o nyearl ybasis , the costo finstallatio n andmaintenanc e of thewate rmanagemen t system is 1t o2 %o f theexistin g values of crops,building s andinfrastructur e ina polder .

Regarding the subsurface drains,som edevelopment s canperhap sb eexpec ­ tedregardin g themateria l tob euse d and inrespec to f the installation techniques.

39- Figure 13.Leve l ofth ebotto m ofth eNort hSea .

40 Therewil lb e afurthe rdevelopmen t towards afull y controlledwate r management.Tha tmean s that tohav e optimal conditions for thecrop s during thewhol eyea r ona larg e scale,no t only drainage,bu tals o irrigation facilitieswil lb e installed.

Thepumpin g outo fwate r canprobabl yb emos t economically realizedb y the combination ofwin d power (back toth epast )an d another sourceo f energy.I n thiswa y theexploitatio n costs canb e lowerbu t investments higher.

Therewil lprobabl yb e developments tostor e thesurplu s of freshwate r in thewinte r tous e thiswate r during dryperiod s inth esummer .

And lastbu tno t least Iwil l finishwit h asayin gmad eb y aforme r president of theUnite d Statesmr .Lyndo nB Johnso nwh o said: "A natio n thatfail s topla n intelligently for thedevelopmen t and protection ofit spreciou swater swil lb e condemned towithe r because of its shortsightedness.Th ehar d lessons ofhistor y are clear,writte n on thedeserte d sands andruin s ofonc eprou d civilizations".

This statementtake ni n thecontex to f thehistor y of theNetherland s in thefiel d ofwate rmanagement ,bring sm e toth efollowing : " If theNetherland s fails tomaintai n theprotectio n ofit spreciou s land against thewate r and tokee p astric tqualit y andquantit y control ofit sequall y preciouswater s itwil lb e condemned tone w disasters.Th ehar d lessons ofhistor y are clear,writte n onth e long list offloodings" .

12 Aknowledgement

The author likes toexpres shi s thanks todr .P.J . Ente,ir .R.J .d e Glopper,an dprof .dr .B .Verhoeve n for theirusefu l comments during thepreparatio n of thistext .

41 13 References

1.Blumental ,K.P . 1982.D ewaterhuishoudkundig e infrastructuurva n Nederland.PT-Civiel eTechnie k septembernummer . 2.Centraa lBurea uvoo rd eStatistiek , 1981.Statistisc h zakboek 1981. Staatsuitgeverij, 'sGravenhage . 3.Hende ,W.R.J .va nder , 1978.Ruilverkavelingswe t 1954.Dee lI . Vijfdedruk .W.E.J .Tjeen kWillink ,Zwolle . 4.Huet , 1885.Stoombemalin gva npolder s enboezems .D egebroeder s VanCleef ,De nHaag . 5.Roya lMeteorologica l Service,1867-1980 .Maandelijks e overzichten vand eweersgesteldheid ,D eBilt . 6.Ramaer ,J.C. , 1892.D e omvangva nd eHaarlemmermee r end emere n waaruithetontstaa nis ,o pverschillend e tijdenvoo rd edroogmaking , JohannesMuller ,Amsterdam . 7.Rijkswaterstaat .Directi eAlgemen eDienst ,De nHaag .

42 LANDAN DWATE RMANAGEMEN T INPOLDER S KanokPranic h 1/ World Bank,Washington ,D.C .

Abstract

By theen d of thiscentury ,th eWorld' s populationwil lexcee d six billions. Thepressur e on land forproducin g food, forurba ndevelopment ,housing ,factorie s and evenfo rrecreatio nwil l be sointens e thana tan y timei nth ehistor y ofmankind . Insearc h forappropriat e land and relatedwater ,peopl ewil lb e compelled not only tomovin g up thehill sbu t also toencroac h into theswamps , floodplain s and tidal landsb y impoldering and reclaiming them.T orea p the fullbenefi t of this latter undertaking,polder swil lhav e tob e carefully planned and executed. Also,lan d andwate rmanagemen twithi n thepolder swil lhav e tob ewel ldesigne d and implemented. Experienceha s shown thatplannin g of allaspect s ofdevelopmen t inth e polder sucha svillages ,park ,woode d area,industria lestate , irrigation drainage,fres hwate r reservoir,far m unit,lan dparcelling , agriculture,etc ,i na nintegrate d manner,i sth ebes twa y for achieving fullbenefits ,eve n ifth e implementationwil lb e carried out instages . Suchplannin g and implementation require close cooperation and coordinated effort ofpeopl e of several disciplines working together.

A3 Introduction

Thepresen tWorl d population isaroun d 4.5 billion. By the turno f the century,i tha sbee n estimated that thepopulatio nwil lexcee d six billion. Thepressur e on land forproducin g food,fo rurba ndevelopment , housing,industr y andeve nfo rrecreatio nwil lb es ointens e thana t any time inth ehistor y ofmankind . Thenee d fordevelopmen twil lb e very realan dpressing . Peoplewil lb e compelled tosearc h formor e appropriate land and relatedwater . Somewil lmov eu p to the hills acid somewil lencroac h into theswamps ,floo d plainsan d tidal landsb y filling or impoldering and reclaiming them.

Objectives ofWate rManagemen t

Theobjective so fwate rmanagemen t is tosuppl ywate r tomee t thenee d of development,b e itfo rdomestic ,agriculture ,industr y orrecreation , and todrai nof fexces swater . Inagriculture ,suppl y of theneede d quantity ofwate r forplan tgrowt h at therigh t time isessential . Also,drainag e isimportan t asi t allows oxidation of thesoi l (bydryin gu p of soils)an dpercolatio no f water foroxyge n supply and for leaching of toxic compounds intoth e subsoil,a swel la s tomaintai n theprope r depth of groundwaterbelo w thesurfac e forplan t roots development. Except for ricean d some otherwetlan d crops,mos t other cropsnee d gooddrainage . Watermanagemen t fordomesti c and industrial uses,i.e . tosuppl ywate r of certain qualities tomee t thedeman d for theseuses ,i sa subjec tb y itself and Ifee l iti sno t inth epurvie wo f this Symposium,excep tt o say that inplannin g thepolder ,th edeman dfo rthes euse swil lhav et o be taken intoaccount . Water brought into thepolde rwil lhav et o provide foradequat e supply tosatisf y theneed so fal lactivitie s planned inside thepolder .

In thepast ,recreatio nwa sa fring ebenefi t created after the construction of thepolder . Waterbodie s sucha s freshwate r reservoir, lake,rive r and canals inside thepolde rwer e alsouse d for recreation — swimming,sailing ,fishing ,bir d sanctuary and thelan d along their banks ascampin g grounds orwoods . Inrecen tyears ,thi sha sgrow nt o

44 become theprimar y user andbenefit s from recreation evensurpasse d several otherbenefits . Inothe r cases,th efres hwate r reservoirma y beuse d forharbou r and assourc eo f coolingwate r for thermalplant . The casei npoin t isi nth eNetherlands . Hence,i nplannin g thepolde r andwate rmanagemen t inside,al lo f theseuse shav e tob e considered. Insuc hcases ,wate r level (elevation)an d quality aswel l asth e control ofaquati cweed s aresom eo f theimportan taspects . InTaiwan , somepolder s along thewes t coast sucha s theTseng-We nPolde rwa s constructed for fishpond san d oysterbeds . Undoubtedly,wate rmanage ­ ment in thesepolder sha d tob egeare d toprovid ewate r level quality,degre e ofsalinity ,etc. ,appropriat e for thepurposes .

Sourceo fWate r

Thewate r resources for thepolde rma yb eeithe r oneo fthese : a) river orstrea mwhic h passes through thepolde r areao rcana l carryingwate r to thepolder ; b) freshgroundwater ; c) natural lakeo rpond ; d) man-madepon d ortank ; e) dugwells ;o ra combinatio n of someo f thesesources . Whena polde r isdesigne d toincorporat e arive r ora strea m running from theuppe r land through it,a sluic e ora regulato r isbuil to n therive r at thelowe ren d of theembankmen t tocontro l thedischarge , volume and levelo f thewate r aswel l as toconserv ewate rwithi n the river channel (freshwate r reservoir)insid e thepolder . However,i n this case thedischarg e and volume ofwate renterin g thepolde r cannot be effectively controlled. Hencemor e often thanno t sluicesar e built atbot h theuppe r and loweren d of theembankmen t tocontro l water entering and leaving thepolder . Examples of thislatte r casear e many: Chandpurprojec t inBangladesh ,Chiangrak-Klongdar nprojec t in Thailand,Hachiro-gat aprojec t inJapan ,an d several tidallan d developmentproject s inKore aan dTaiwan . Anexceptio n toth eabov ear esevera lproject s inth emiddl epar to f

45 theIrrawadd y delta, where horse-shoe shaped embankmentswer ebuil t leaving thelowe r end ordownstrea m sideo f thepolde r openan d sluices werebuil t at theuppe r end. River floods canente r slowly through thisope ndownstrea m sidebu t thedept h of flooding and the flooded area aresmalle r thanwithou t theope nembankment . InThailan d (Chlangrak-KlongDar n Project), several canalswer edu gt o conveywate r from thenearb y river into theembanke d area. These canals areuse dmulti-purposely ,a ssource so f irrigationwater ,fo rconserva ­ tion tostor ewate r during thewe t seasonfo r usedurin g thedr y season,an d asdrainag e channels aswell . Somepolder s are located in thedelt ao ralon g these a coastwher e aquifersbearin g fresh groundwater exist. Insuc ha case ,tubewell s can be sunk toextrac t thegroundwate r forus ewithi n thepolder . However, as soils inth edelt a and along these acoas t aregenerall y alluvium, excessivepumpin gwil l cause land subsidence. Exampleso f thisca nb e found inth edelta s of theTon eRive r andNagar aRive r inJapan ,an d many otherplace s in theWorld . Also lowering ofwate r level inth e aquiferma y cause seawate r intrusion into theaquifer ,i nparticula r for thepolder s along these a coast. In thecoasta l (embankment)polder s ofBangladesh ,an d severalpolder s inBurma ,farmer sals ous eshallo wdu gwell s (5-10m .depth )a ssourc e ofwate r fordomesti c supply and irrigation. Natural lakes,pond s of adequate quality ofwate r canan d areuse d as sources ofwate r inth epolder . Oftenman-mad e pondso r tankshav ebee n built tocollec t and storewate r duringwe t season forus edurin g the dryseason . Thesourc eo fwate r for thepolde rma yb e either oneo f theabov e ora combination thereof.

Drainage

Inpolders ,drainag e comesbefor e irrigation and isconsidere d more important. After impoldering iscompleted , thepolde rwil lhav e tob e drained dry. The soils,generall y comprises largely of clay and silt with smallpercentag e ofsand ,hav e tob eripene d 2/,agai nb ymean so f drainage togetherwit h the cultivation of reclamation crops sucha s

- 46- rice,barley ,wheat ,ree d orgrass . Where climate issuitable ,ric ei s anexcellen t reclamation crop. Iti ssomewha t salt tolerant. Iti s grownunde r flooded conditionwhic h allows flushing and leaching process tog oo nconcurrentl ywhil e land isunde r cultivation.

Drainage forReclamatio n

After thecompletio n of embankments and sluices (and inman y cases pumping stations)an d the land iscompletel y enclosed, drainageb ypumpin g and sluicing shouldbegin . After that thecons ­ tructiono fmai ndrainag e canalshoul d be started. Natural creekso r channelsma yb euse d asmai ndrai n if their elevation and locationar e suitable. Smaller creeksma yb euse d assecondar y drains. Shallowan d meandered creeks should bedeepene d toth erequire d depthan d straigth- ened asappropriat e and theexcavate d soilsuse d forfillin g upothe r small creeksan d depressions. If themai ndrai nha s tob enewl yexcava ­ ted,i n theinitia l stage,whe n thesoil s are stillfull y saturated and very soft,th edept hma yb ekep t shallowan d slide slop flatter. It willb edeepene d toth e finalcros s sectionafte r thesoil shav ebee n ripened. Secondary drainsma yb eexcavate d concurrentlywit h land levellingan d filling upo funwante d creeks. Liketh emai ndrain ,i f thesoil sar e soft, theyma yb edu g smallerwit h flat sideslope s first and made deeperwit h steeper sideslopes . Thespacin g of thesedrain si s designed according toth edifferen t kinds ofsoil san d isgenerall y ranged fromabou t 400m (Thailand ChaoPhy aDelt a -heav y clay) toabou t 600m (JapanHachiro-gat a -sand y soils). For reclamation and ripening of soils,fiel d drainsar egenerall y needed. Thehighe r thecla y content inth esoil swil lrequir e the smaller spacing between thefiel d drains. Ingeneral ,th espacin g rangesbetwee n 20m to10 0m . After afe wyear swhe n thesoil shav e been ripened fully,thes e field drainsma y beback-fille d togai n more land.

47 Drainage forAgricultur e

Forgoo d cropsgrowt h thegroundwate r should bekep t about 1.4 to 2m below thelan d surface. If thegroundwate r isbrackish ,th eminimu m levelo f 2mshoul d probablyb eused . Thismean s that thesecondar y and maindrain s should beadequatel y deep toaffec t suchgroundwate releva ­ tion. However,fo rric ewhic h isa wetlan d crop,suc h conditionma yno t be required so long as therei ssom emovemen t ofwate r through theroo t zone. Hence,drainag e canals inpolder s catering only forric e are generallyshallowe r than thosei nwhic h dryland cropsar egrown . Ingeneral ,th e landelevatio n inth epolde rha s tob e sufficiently high (more than1 m abovemea nse alevel )t o enabledrainag eb y gravity to beeffecte d through sluices,takin g advantage ofeb b tidea fe whour s eachday . For lower elevationo fland ,pumpin g togetherwit hsluicin g mayb enecessar y and if thelan d surface isbelo wmea n sealevel , drainageha s tob eeffecte d entirelyb ypumping . Thismake s theprojec t moreexpensiv e inbot h the capitalan d operation costs. Inth edesig n of thepolders ,location s ofpumpin g stations and sluices are important asals o theelevatio n of the sillso fsluices . Sluice sillsshoul db e placed as lowa spracticabl e toimprov ehydrauli c capacity. Whenth e land elevation islow ,no tonl y drainage ismor edifficul tbu t alsoth e construction ofembankments ,irrigatio n and land andwate rmanagemen t becomemor e complicated andmor e costly. For thisreason ,severa l countrieshav e established land elevation criteria for thedevelopmen to f their tidal lands. InIndi a (Sundarbans),th elowes tpermissibl e levelo f land forreclamatio n ismid-wa y betweenhig h spring tidean dhig hnea p tide. InIndonesia ,th elan d elevationha s tob ebetwee nmea n sealeve l andhig h tide.I nMalaysia ,th e elevationha s tob eabou t1.2 m above meanse a level.I n SriLanka ,th eminimu m elevation of thereclaime d coastalarea s isabou t 0.3 m abovemea n sealevel ,wherea s inThailand , thiselevatio n isabou thig hnea p tide. InJapa n (Hachiro-gata),th e minimum elevation of land inside thepolde r is4. 5 mbelo wmea nse a level. Elsewhere inJapan ,wher e land forindustr y and urban development was reclaimed by filling,lan da slo wa s-1 0t o-1 5m MS Lha dbee nreclaimed . There are certainkind so fsoil swhic h call for specialkin d of drainage andwate rmanagement . Forbot hCa tCla y (oraci d sulphate)an dpea tsoil s fordifferen t reasons,th egroundwate rwate r levelshoul d notb elowere d

- 48- toomuch, -0.6 0to-0.9 0m shouldb e sufficient. Whensoil s are drained aerationoccurs . Forpea t soilsoxidizatio n and land subsidencewil lb e excessive if thegroundwate r islowere d too farand,fo raci d sulphate soilsoxidizatio nwil l accelerate theformatio n ofaci d (sulphuric acid)in thesoils . Incountrie swhic h aresubjecte d tomonsoo n and typhoonrainfall san d whereric e isgrown ,th epadd y fieldswhic h generally have lowfiel d dikesal laroun d areuse d tostor eexces srainfal l temporarily,i norde r toreduc e thecos to f thedrainag e system. Paddy canstan d submergence ofu p to 7day swithou tmuc h effect. InJapan ,Hachiro-gat apolde r in Akitaprefectur ewa s designed tostor eexcessiv e rainwater on thepadd y fields temporarily,equivalen t to 77m m orabou t one-third of themaxi ­ mum threeday srainfal l of 220mm . Thisreduce s therequire d capacity 3 3 ofpumpin g stations from15 0m /secdow n to8 0m /sec. InBangladesh ,a drainage criteriao f 25m mpe rda yha sbee nadopte d forarea swit ha n annualrainfal l ofabou t175 0m man d for other areas inproportio nt o thisamount ,base d on theassumptio n that crops canb e submerged to a deptho f 150m mwit h little damage.I nThailand , thedrainag e systemwa s designed todrai n the threeday smaximu m rainfalls in 7u p to1 0days . For coastalo r tidal landpolders ,th eclosur eo f therive rmout ho r estuaryb y sluices tocreat e alarg e freshwate r reservoirwil lhel p improvedrainag e andwate rmanagemen twithi n thepolder . If theseepag e through these adik ei sexcessive ,a seepag e canal(drain ) mayb e constructed near the toeo f thedik e toarres t thebrackis h water orels e theseepag ewil l spread further inside thepolde ran d damaging thegoo d land.Th ecana lwate r can theneithe rb epumpe d outo r drained through sluices ora combinatio n ofboth ,a s the casema yhe . In thepresen t day,mor ean dmor e subsoil drainage through tiledrain s orplasti cpip edrain sar ebein g used. Although this typeo fdrainag e initially costsmor e than theope no r surfacedrain ,i ti smor eeffect ­ ivei ncontrollin g thegroundwate r levelan d the losso f land isminima l compared toope ndrai n system. Theoperatio n andmaintenanc e costi s also lower. Inparticular ,i f thegroundwate r issaline ,th eadoptio n ofsubsoi ldrain s should beencouraged . Theaverag e cost ofsubsoi l drainage ranges fromabou tUS$75 0 toUS$150 0pe rhectare ,dependin g on thedept h and spacing of thedrain s aswel la s the typeo fsoil san d theleve lo fgroundwate r during theinstallation .

49 Irrigation

Themai nprincipl e of irrigation ist oprovid ewate r accordingt oplant sneed . Whenrive r is thesourc e ofwate r for thepolder ,th emai n canal takingwate r from therive r should be located farenoug hupstrea mbeyon d thereac h ofse a water intrusion. Whenfres hgroundwate r isth ewate r source,pumpag e has tob e limited not toexcee d theinfiltratio n rate into theaquifer , soa s topreven t land subsidence. Asmentione d earlier,natura lcreeks , ponds and tanksar eals ouse d assource s of irrigationwater .Also,fres h water reservoir canb e created asgoo d source ofwate rb y closing the downstream end of therive r orcreek ,o rb yclosin g therive rmout h orestuar y at theimpolderin g embankment. Irrigationma yb eeffecte d by gravity througha syste m ofmai n and secondary canalsan d field channels,o rb ypumpin g fromwate r source into thegravit y systemo fdistributor y canalso rb ypumpin g through sprinkler system (sprinkling irrigation). Theplannin g ofirrigatio n and drainage shouldbegi na t thefar m level andwor kupstrea m to themai n canalan dheadworks . Whether irrigation (anddrainage )wil lb eeffectiv e and efficient depends agrea t deali n theplannin g and designo f thefiel d irrigation channels and field drainsa t thefar mlevel . Whenlan d isreclaime d from thesea ,afte r thepolde rha sbee ndraine d and thesoil s ripened,irrigatio nwate rha s tob e supplied for leaching and flushing ofsalinit y from thesoils . When soils contain alarg e percentage ofsand ,leachin gwil lb ever y effective and crops likeric e canb egrow nafte r onlya fe wmonth s of leachings. InHsin-Ch uTida l Land on thewes t coast ofTaiwa nwher e soilscontai n 70-90%o fsand , ricecro p couldb e grownonl y after 2-3month s of leachingwit h fresh water and theyiel d inth e firstyea rwoul d almostb enormal . However, if thesoil s contain largepercentag e of clay,i twil l take 1-2year s orma yb e longerbefor e theintende d crops canb egrown . When irrigation isb y gravity through canals,th eamoun t ofwate r supplied asdetermine d by cropwate r requirement or evapo-transpiration, divided by irrigation efficiency toarriv e atirrigatio nwate r requirement,i sgenerall y sufficient forleaching ,t okee p thesoi l salinity under check. However,i f irrigation isb y sprinkler,som e

- 50- additional amountma yb eneede d for leaching. Genelly,i fabou t 10t o15 % ofcro pwate rrequiremen ti sallowe d fo rthi spurpos e, i twil lb esufficient . Most soilscientist swil l agree thati f the land comprises ofpotentia l cat clay oraci d sulphate soil,i ti sno twort h reclaiming. Iti s difficult and costly toimprov e thesoi la swel la s tomanag e the drainage and irrigation,an d yet theyiel d ofcrop s grownwil lneve rb e high. However, therehav ebee n such land insom eo f thepolders . There aresevera lway s of tackling suchsoi l: a) By theapplicatio n of lime toneutraliz e theacidity . However,a largequantit y of limewil lhav e tob eapplied ,rangin g from 30u p to2-30 0ton spe rhectare . Also,additiona lquantit ywil lb e required every fewyears . Thismake s themetho d costly and even prohibitive. b) Bypuddlin g thelan dwit h freshwate r and flushing and draining several timesbefor e rice isgrown . Thismetho d ispractice d in Japanan d Thailand. c) Bykeepin g thegroun dwe t orsaturate d all the time,thu sreducin g oxidation. In tropical countries thisca nb edon eb y growing two crops ofric epe ryea r orb ykeepin g thegroundwate r tablehig h (if thegroundwate r is fresh). d) Byploughin g and flushing thelan dwit h seawate r and subsequently leaching and flushing itwit h freshwater . Thismetho d isemploye d inVietna m and SierraLeone . Evenwit h theemploymen t of theabov emethods ,aci d tolerant crops should be growno n this soil. Some of these crops areric ean dpine ­ apple in the tropics and reeds and grass inth e temperateregion . Planning of irrigation and drainage systems should start from thefar m levelu p to theheadwork s orreservoi r andno t theothe rwa y around. Suchplannin gwil l ensure that therequiremen t at thefarm swhic har e productive units,i nparticula rwit h respect to thewate r leveli n relation to theelevatio n of thelan d surface,wil lb emet .

51- Therear evariou s typeso f layout of farmparcel s comprising irrigation and drainage channelsan d farm roads (and insom ecase swin d breakers). Theselayout s aregenerall y designed tosui t the topography,soils , hydrometeorology,hydrogeology ,agricultur e (cropgrown )etc .o fth e polder. However,th egovernin g principle of these layouts isth esam e thateac h farmuni t shouldhav edirec tacces s toth eirrigatio nsupply , drainage and afar mroad .

Separate orCombine d Irrigation andDrainag e System

Thesyste m comprising separate irrigation and drainage channels atfar m levela sexplaine d above isth ebes t foragriculture . Itgive sbette r andmor eefficien twate r control'andwate rmanagemen t than thecombine d system. Irrigation ordrainag e ofan y oneparce lo runi t of land can be carried outa tan y time independently tosui tplant snee dwithou t affecting theothe rparcels . Foragricultur eaimin g athig h intensity ofcrop s ofhig hyields ,th eseparat e system ispreferred . However,thi ssyte m costsmuc hmor e than thecombine d system and the operationan dmaintenanc e costs of thesyste m isals ohigher . Hence, insevera ldevelopin g countries the combined systemha sbee n employed. InJapa n (Hachiro-gata Project),Kore a (DongJi nGang ,Yon g SanGan g andPyongtaek-Kumgan gProjects) ,an dTaiwa n (WestCoas tTida lLan d Development Projects),wher e agricultural development hasreache d high levelwit hhig h cropyields ,separat e systems of irrigationan d drainagehav ebee n employed. InBurm a (PaddylandDevelopmen t Projects inth eIrrawadd y Delta),Banglades h (Chandpur Project), SriLank a (SouthwestCoas tDrainag e andReclamatio n Project),wher e agriculture development isstil l inth eintermediat e stage,a combine d irrigation and drainage systemha sbee n adopted.I nthes epolders ,natura lstream san d creekshav ebee nredredge dan d closedb y sluices toac ta sreservoir sfo r water conservation,irrigatio n canalsa swel la sdrains . Inal l these projects,farmer sus e smallpump s (generally 3-5 hp.)t olif t water from thenatura l streams for irrigating their lands. Moreover, theChandpu rProjec t inBanglades hha s alarg eprimar y pumping station

- 52- (34e um/ sec)a t themai n sluice topum pwate r inan d out of thepolde r foreffectiv e control ofwate r inside thepolder . Farmers in thepolde r own 1500pump s of 70 lt/sec for irrigation. A special feature of thisprojec t is that farmerswer e trained inirrigate d agriculture by actually doing itbefor e theprojec twa s completed. Hence,b y the timeo fprojec t completion theywer e ready. Theprojec t inSr iLank a also has severalmediu m sizepum p installed at themai n sluicest o help improve thecontro l ofwater ,i nparticula rwate r level,insid e theembankments .

Land Consolidation

Unlike theexistin g agricultural land,th enewl y reclamimed land canb e laid outan d subdivided intorectangula r farmunit sideall y appropriate forhig hproduction ,wit h eachuni t served by anirrigatio n channelan d a drainan d connected toa farmroa d forbringin g theproduct san d implements inan d outo f the farm. Hence,i t isrecommende d thatlan d consolidation layout beemploye d in.th enewl y reclaimed land. Asmentione d earlier, the tidal land reclamation inJapan ,Kore aan d Taiwan,al lemploye d land consolidation. When there ispersisten t strongwin d fora lon gperio d of timesuc ha sa t the tidallan d development projects in thewes t coast ofTaiwan ,wher e strongNN Ewin d averaging 35-40k mpe rhour sprevail s fromOctobe r toMarch ,win d breakers in thefor mo f tworow so f treesar egrow no nbot hside so f thefar m road toprotec t thecrop sa swel l as toreduc ewate r lossesi n thefar m throughexcessiv e evaporation. Hence,ther ear e tworow so f treesever y 4-500meters . The treesgrow nar eo fvarietie s ofwhic h their leaves canals ob euse d asgree nmanure .

53- Planning ofLan d andWate r Management

Theplannin g of land andwate rmanagemen tha s tob emad e at the timeo f planning thepolder . The location and sizeo fvillage , park,woode d area,industria l area,fres hwate r reservoir,etc. ,a swel la s thesiz e of farmunit ,lan d parcelling,includin g roads,far m roads,win d breakers,etc. ,a swel la sagricultura l development should beplanne d togethera sa n integratedwhole ,eve n though their implemen­ tationma yb edivide d into stages forshor t and long-termdevelopment .

Ihav e seenpolder splanne d and constructedwithou tprope r drainage nor irrigation,an d farmersha d cut theembankmen t tole t floodscause d by raint odrai noff . Inothe r case,farmer sals o cut theembankmen t tole twate rbacke d upb y tides tocom e inth epolde r for irrigation. No oneca nblam e thefarmer s inbot h cases. As thepolder swer eno t wellplanne d and executed, farmer sha d tohel p themselves. As theplannin g and designo f thepolder s isa n intricate and complex task,requirin g experienced professionals insevera l fields sucha s hydrologist,geohydrologist ,soi l scientist,engineer ,agriculturist , economist,etc. ,i ti sa mus t thatcooperatio n ofeffort sb y these specialists beensure d from thestart ,beginnin g with collectiono f data,planning ,desig n tillprojec t implementation. Torea p substantialbenefit s and good return from thepolde rproject , adequatewate rmanagemen t isa must ,otherwis e therema yb enegativ e effects toth eexten t that farmersma y cut theembankmen t asafore ­ mentioned.

Footnotes

_1/ The'Viewsexpresse d inthi spape r are theauthor' s ownan dno t necessary of the institution towhic hh ebelongs . 2/ To change frommu d to firmer soil. The ripening of soils comprises threemai nprocesses : decrease inwate r content,formatio no f cracks and subsidence of land surface.

54- CONSTRUCTIONASPECT S

- P.C. Masure. Thedevelopmen t of theDutc hpolde r dikes - R. Segers. Fromwindmil l towind-generator . Development inpolde r construction - U.A. Meyer. Construction aspectso fpolder s inth e world

- 55- 56 THEDEVELOPMEN TO FTH EDUTC HPOLDE RDIKE S P.C.Mazur e TheNetherland sWate r Defences Research Centre TheHagu e TheNetherland s

Abstract

As aresul to f thevariet y inth eorigin s ofpolder s several categories of poldershav edevelope d inth eNetherlands . The specific development inth econstructio no f seadikes ,rive rdike s andbel tcana ldike s is illustrated inth epresen tpaper . Inth epas t thecomplet edesig nwa sbase d onexperienc e collected ina process of trial anderror . Modern designmethod sutiliz eknowledg e obtained about loadsactin go na dikean d thestrengt h of theconstructiona lelement s of thedike . Inrecen tyear s studieshav ebee n intensified towards theprobabilisti c designmethod .I nth efutur eth edesig nwil lb ebase d ona calculatio n of theris k offloodin g of theprotecte d polder.Howeve r atpresen t the resultso f thestudie s todat eca nb euse d toimprov e the traditional ordeterministi c designmetho d until theprobabilisti cmetho d becomes completely applicable.

1 Introduction

Themajo r parto f theNetherland s consists ofpolders .A s aresul to f thevariet y inth eorigin s of thesepolder s andvariation s inloca l circumstances several categories of poldershav edeveloped . Sincemedieva l timespeopl eprotecte d comparativelyhig h levelarea s along seacoasts and riversfro m frequent floodingb ybuildin g small

- 57 dikes.Drainag e of thesepolder s tookplac eb y gravity throughsluices . Soil subsidence in theolde r polders necessitated achang e from gravity drainage toartificia l drainageb ywindmill s orpumpin g stations. After thedevelopmen to fwindmill s and pumping stations poldersals o were constructed incomparativel y lowleve l areas,suc h aslake san d marshes.Man yo f thelake swer e theresul to f thediggin go fpea tfo r fuel. Inrecen t times evenpart so f these aan d inland seashav ebee n impoldered.

Asresul to f successive impoldering activities aver y complicated systemo fpolder s anddrainag e systemsha sdevelope d (figure1) .

PAMPUS

i4t4 — belt canal 2 land level in m below MSL

Figure 1. Example of a complicated system of polders and belt canals near Amsterdam

58 The levelso f thevariou s poldersrang eno wfro m 2m above to6 m belowmea n sealeve l (MSL). Thedrainag e systemfo r allpolder s consistso f aserie so f natural waterways and excavated canals,togethe r forming astorag ean d transport system toconduc t superfluous polderwate r to these ao r toth erivers . Thispape r dealswit h specificdevelopment s inth econstructio n ofsea , river andbel t canaldike sresultin g from thevariet y inorigi no f these dikes.

2 Seadike s toprotec t seapolder s

Partso f theDutc hNort h Seacoas tar eprotecte d naturally against the seab ydunes .Wher edune sd ono t existo rhav edisappeare d becauseo f coastalerosio n and alsoalon gbranche so f the sea,lo wlyin g areasmus t beprotecte d against inundationb y these ab y approximately three hundredkilometre so f seadikes . Manyo f thesedike shav egrow nove r centuriesfro m smallembankment s made of locally excavated materials (mainly clay)int oenormou s constructionsmad e frommaterial sbrough t in,especiall y sand.Th e local soilwa sno t always ideally suited to theconstructio no f impermeable dikesbu t informe rday s transport of largequantitie s of soilwa s impossible,especiall ywher e thesedike sha d tob e constructed intida l areas.Henc eth eslope so f these "old"dike swer emad e as steepa s possible tominimiz e thequantit yo f soil.Th ecres to f thedik ewa s determined by thehighes t flood levelpeopl e could remember.Th estee p outer slopes,ofte nalmos tvertica lwalls ,wer eprotecte d againstwav e attackb y allkind so fmaterial s likewood ,ston e (glacialboulders) , bricks,rubbl ean d grass-sods (figure 2);eve ncompacte d seaweedwa s used for cofferdam construction along thebranc ho f seano w called the IJsselmeer.Knowledg e about theus eo f thesematerial swa sfounde d on practiceunde r the specific circumstances indifferen t areaso f the Netherlands.Thes e areaseac hha d theirow n specific construction methods,base d on localknowledg e and availablematerials .Eve ntoda y thesedifference s inconstructio n canb eseen .

The introductiono fmechanicall y drivenbucke t and suctiondredgers ,

- 59- Figure 2.Cros s sectiono f anearl y seadik e hopperbarge s andothe rmean s of transport inth e second half of the nineteenth century facilitated the transport ofgrea tquantitie so f soil overgrea tdistance . Thisdevelopmen t had agrea t influence on the shape and construction ofdikes ,particularl ynewl ybuil t seadike s anddams .Fro m theno n materials couldb e chosenbase d on their properties inrelatio n tothei r function inth econstructio no f thedik ebecaus e soil could thenb e obtained inlarge r quantities and from agreate rdistance .

Thecor eo f amoder ndik ei smad eo f greatquantitie so f sand,brough t intoplac e ashydrauli c fill.Thi s sand iscovere d with acla y layero f a thickness of about 1m . Side slopes areno w chosen at 1:5 to 1:7o n the seaward sidean d 1:3 to 1:4o n thepolde r side (figure3) .

As alreadymentione d theprotectio no f thedik e againstwav e attackwa s originally constructed ofvariou smaterials .Howeve r since thepresenc e of thetered owor m ruled out theus eo fwood ,protectio nwa sprovide d mainlyb y turf.Wher egras s could not growdu e to thesalinit y of the sprayo n lower levels theslop ewa s covered by amattres so fwillo w twigsballaste d with stones.Fro m themiddl eo f the 18thCentur y the

- 60 ,-^r

Figure 3.Developmen t incros s sectiono f ase adik edurin g theperio d 1812t o 1963 outer slopeswer eprotected ,u p to 1.5m above stormfloo d level,b ya revetmento f stones imported fromforeig ncountries . After theSecon d WorldWa r concreteblock swer e introduced. Thenee d torepai r great lengthso f seadike s ina shor t timeafte r the 1953disaste r inth eSout hWester npar to f theNetherlands ,th es o called Deltaarea ,lea d to theintroductio no f asphaltrevetments .Thi s hasnecessitate d entirelyne wdik e constructionswit h asphalt revetments overlying directly the sand core (figure4) .

*£T • asphalt cz. 3 sand v y / j clay 11 i i ii mine waste "'"""i concrete blocks imji rubble 8,70m 6,85m DESIGN WATER LEVEL + 5,65m

Figure 4.Cros s sectiono f ase adik ewit h asphalt revetments

- 61- Asmentione d earlier theheigh to f adik ewa sfo rman y centuriesbase d on thehighes tknow nfloo d level thatcoul db eremembered . Consequently after theoccurrenc eo f adisaste r due toovertoppin g oroverflowin g furtherheightenin g of adik ebecam e gradually lessurgent ,ove ra period of years,especiall ywher e alarg e amount ofmone ywa snecessary . Generally some limited measureswer e takenwhic h provided ane w yardstickvali d for some timeunti l afloo d occurred with aleve lwhic h exceeded theol done .

Iti seviden t thati nthi swa y therea l risko fdamag eo r the probability offloodin gwer eunknown .Littl ewa sknow nabou t the relationbetwee n thecos t topreven t flooding and thecos to f the damage that.migh tresul tfro mflooding .Economi c comparisonwa sno t made;peopl e asked fordr yfee tpreferabl y atn oexpense .Th eheigh t thatdike s shouldhav ewa s thesubjec to f animated discussion.

In the20t h Century itwa sfoun d that theoccurrenc e of extremelyhig h water levels at seacoul db edescribe d adequately interm so f frequency inaccordanc ewit h thelaw so fprobabilit y calculus.Howeve r the curveso fextrem ewate r levels,base d ona relativel y shortperio d ofobservations ,hav e tob e extrapolated intoregion s farbeyon d the field of observation (figure5 ).

The 1953disaste r provided proof for thetheorie sdevelope d forth e probability of exceedance ofhig hwate r levels.Fro m studieso f the DutchRoya lMeteorologica l Institute,initiate d in 1953,i twa s concluded thatconsiderabl y higher flood levels thanth eon eobserve d in 1953wer ephysicall y possible and thatn opractica l level could be givenwhic h couldneve rb e exceeded; therefore therewil l alwaysb esom e finiterisk .Th efrequenc y of theris ko f floodingwa s studied in relation toth eeconomi c aspects.Thi smatte rwil lb e discussedbelow . Aftermuc h discussion itwa s decided tobas e thedesig no f all seadike s -4 fundamentally ona wate r levelwit h aprobabilit y of exceedance of 10 per annum.

62 -2 ,-3 -5 6 7 10 10 10 1 10 10 10 10-u 10 10~ n 10" frequency of exceedance per annum

Figure5 .Frequenc y of exceedance ofhig hwate r levels atHoo ko f Holland For example thestor msurg eleve lo f 1953,3.8 5m aboveMS L has afrequenc y of 1/300 per annum.

Severalothe r elements alsopla y arol e indeterminin g thedesig nleve l of ase adike : - waverun-u p dependingo nwav eheigh t andperiod ,angl eo f approach androughnes s of theslope , anextr amargi n toth edik eheigh t totak e into account seichesan d gustbump s (singlewave sresultin g froma sudde nviolen trus ho f wind), - achang e inchar tdatu m (NAP)o r aris e in themea n sealevel , subsidence of the subsoil and thedik edurin g its lifetime . Based on thesefactor s thedesig n level of ase adik e canb edetermine d as showni ntabl e 1.Th eprofil eo f such ase adik e isshow n infigur e 3.Wit h thepresen tdesig n criteria thecros s sectiono f amoder n sea

63 Table 1.illustratio n ofdeterminin g design level

flood level MSL+ 5.00m wave run-up 9.90 m seiches and gust-bump 0.35 m risingmea n sea level (MSL) 0.25 m settlement 0.25m

Design level MSL+ 15.75m dike istwic ea shig ha s theol d dike thatprecede d itbefor e the 1953 disasterwit h afourfol d increase involume .

To constructmoder n dikes thecla yo f the inner slopeo f theol ddik e isgenerall y dug away and stored and thesan d of thene wdik e isfille d inagains t theol ddike .Afterward s the stored clay isuse d tocove r the sand core.I nth ewav e attack zonea revetmen t of stone settso r asphalt ismade .Becaus eo f thefla t slopesno w inus e slope stability problemswil l seldom occur.Despit e theenormou swidt ho f thewhol e dike construction animpermeabl eblanke tmad e of clayo rasphalt , applied toth e seaward slope,o r an impermeable coreo f clayi s essential topreven tseepage .

Thehistorica l development of thedesig nmetho d canb e traced.I nth e past thecomplet edesig nwa sbase d onexperienc e collected ina proces s of trialan derror . Developments inmechanic s (from 1920especiall y soilmechanics )hav e brought achang e inthes emethods .Th emoder ndesig nmetho d utilizes knowledge of thepropertie s of soilmateria l and subsoil obtained from field and laboratory tests,knowledg e of ground water flow andwate r pressures,knowledg e of thebehaviou r of thedik ebod y and therevet ­ mentunde r thewav e attacketc .

3 Riverdike s

River dikeswer emad eb yma n towithstan d thehighes t floodlevels .

- 64- Originally thesedike swer eonl y small,positione d along therive r banks and carryingroads . Thepresen t form and height of theserive rdike swa s achieved byth e heightening of thecres tonly ,usin g allkind so f locally available soil and asa consequenc e the inner slopebecam emor e andmor esteep , reaching even 1:1.5 inplace s (figure6) .

£0m t- H Figure 6.Developmen t incros s sectiono f arive rdik e inth ecours e of time

As aresul t the inner slope could becomeunstabl e duringperiod s ofhig h riverwate rlevel . Theserive rdike s are allovergrow nwit hgras s and theslope sprotecte d by arevetmen t only onplace swher e severe erosiono rwav e attack can be expected. Thanksno w tobette r transport facilitiesmor e suitablematerial s are used forreconstructio n sucha s clayfo r imperviousrevetment s onth e outer slopes and sandy clayo n the inner slopesmakin g for flatter slopes.

Inth epas t theheigh t of arive rdik ewa s determined by thehighes t flood level thaton ecoul d remember and only asmal l allowancewa smad e forwav erun-up . Before 1950 theconstructio no f thesedike swa smor e or lessbase d upon

- 65 experience andman ydisasters ,cause db y inundation and failure,wer e theresult .Inure d toinundations ,peopl e learned toliv ewit h this risk and ingenera l theybuil t theirhouse s near too r on thecres to f thedikes .Th egrowin g population and changes inagricultur ehoweve r havemad e itnecessar y tohous epeopl e in thepolder s aswel l aso nth e dikes.Du e to thisa bette r protection against inundationha sbecom e essential. Today,th e incidenceo f extremehig hwate r levels canb e represented in termso f frequency,usin g the samephilosoph y asdescribe d abovefo r seadikes . After yearso f discussion about technical and environmental aspectsi t was decided tobas e thedesig n levelo f themai nrive rdike so na wate r level corresponding toa discharg e thatca nb ereache d or exceeded -4 . 8x10 timespe ryear .A tpresen t areconstructio n program isbein g carried out tostrengthe n themajo r parto f thefou rhundre d kilometres ofrive rdikes .

Reconstruction of thesedike s isespeciall y difficultbecaus e of the environmental aspects.Th ereconstructio nofte n destroysvaluabl e vegetation onth eslope swhic h probablywil lno tretur n to thene w flat slopes.Man yhouse s and farmhouseswit hhistorica lvalue ,buil t ono r into thedike shav e tob edemolishe d ordik e reconstruction minimised or executed withver yelaborat e techniques inorde r topreven t demolition.

Inth e easternpar to f theNetherland s the subsoil of therive r dikes often consists of acla y stratumo f athicknes so f 2t o6 m overlying a sand stratum of 20m ormore .O nman y spots therei sa nope n connectionbetwee n thesan d stratum and therive rbe dwhic h causesa transmission of thehig h floodwate r pressure to theundersid e ofth e clay stratum at the toeo f theinne r slope.Thi spressur ema y endanger thestabilit y of thecla y stratum and can lead to itsbrea kup , followed by internal erosiono f thesan d (piping).Th ehig hwate r pressure inth e sand stratumma y threaten thestabilit y of theinne r slope,addin g to the threato frive rwate r percolating through thedik e (figure7) .

- 66 *" • ' .'•• .'"• failure mechanisms before reconstruction

design river level 1D.R.L) ,xS555^^ clay

r

river dike after reconstruction

Figure 7.Cros s sectiono f arive rdik ebefor e and after reconstruction

In thewester n parto f theNetherland s peat strata inth e subsoil can cause considerable subsidence. Therefore extensive investigations of thesubsoi l and the soilmateria l used fordik e constructionmus tb edon ebefor ereconstructio n toobtai n data (mainly soilproperties )fo r designcalculations .

An inner slopeo f 1:3 to 1:3.5 isrecommende dwit h animpermeabl e cover of clayo n theoute r slopean d on thefloodplai nadjacen t to thefoo t of theslop e topreven t thepercolatio no f flood water.A permeabl e horizontalblanke t adjacent toth einne r slopewil lpreven tbrea ku p and theprobabl e subsequent piping and collapseo f thedike .Th ewidt h of this cover isstil l designed by empiricalmethod sbu t inrecen t yearsmode l studies and insit u testshav ebee n carried out toobtai n more exactdesig n rules,d eWi t eta l (1981).

67 4 Belt canaldike s

Forman y centuries inth ewester n parto f thecountr y the impoldering of lakeswa snecessar y tosto p theprogressiv e erosiono f thebanks .I n additionpeopl ewh odu gpea t forfue lwer eoblige d toimpolde r excavated areaswhic hha dbecom e artificial lakes.Anothe r process that led toth eformatio no fpolder swa s thedrainag e and agriculturalus e of peatmarshes .I na fe wcenturie s theleve lo f thesepeatland sbecam e solo wtha tprotectio nb ydike s and artificial drainagewa sessential .

Inth eexcavate d areas small canalsha dbee n leftfo rwate rmanagemen t and for shipping.Th esmal l stripso f land alongside these canalswer e used asdike swhe n drainage started with thepumpin g ofwate r fromth e lakeint o the"belt "canal . "Belt" canalswer e excavated around large lakes andwit h thesoi ldu g from thesecanal s (oftenpeat )a bel t canal dikewa smad ebetwee n the canal and thelake .Thes ebel t canalsremaine d parto f theexistin g systemo fwaterway s to transport superfluouswate r tose ao rrive ran d forus eb yshipping .

During theproces s of impoldering over thecenturie s inth ewester n parto f our country aninterconnecte d networko fbel t canalsan d thousandso fkilometre so fbel t canaldike shav e comeint obeing .

The subsoil inthi s areamainl y consistso f stratao fpea t and soft clay.Becaus eo f this soil severe subsidenceo f thedike sha soccurre d ata rat eo fu p to0.0 5 to0.1 0 m per annum insom eareas .A s thewate r levelo f thebel t canal and thewhol e systemo f canals to the seai s kept constant thisha snecessitate d thefrequen theightenin g of the belt canaldike s (up toonc e every 2o r 3years) .Heightenin g has usuallybee n carried outusin g locally availablematerials .Thi s processha sresulte d ina ninhomogeneou s top layerwit h athicknes so f up to4 to5 m , consisting of dredgedmud ,peat ,clay ,rubble ,ashe s and sometimes sand (figure 8).Often ,th eadditiona lweigh t causedb y thisheightenin gha sproduce d further subsidence.

When,b y progressive subsidence,layer so f rubble,ashe s and sand polder dike - belt canal dike - deep polder M.S.L

sand • ..• 40m Figure 8.Cros s sectiono f abel t canalwit hdike s

(whether old revetmentmateria l orroad-metal )disappea runde rbel t canal level theyma y cause seepageproblems .Whe nheightenin g isdon e simplyb yplacin g aca po f clayo n thecres to f thedik e theinne r slope becomes steeper and stability problemsma y arise inadditio n toth e problemsdu e to thesof t subsoil onwhic h itrests .

The questfo r safebel t canaldike sha sbecom emor e important sincea growingpopulatio n and industrialisation has necessitated building in low levelpolders .Usuall y peopled ono trealis e fullywha t canhappe n when abel t canaldik ebursts .Th e lowleve lpolde r isinundate d completely by the largequantit y ofwate r stored inth eextensiv ebel t canal system and inadditio ndamag e canb edon ewhic h isdifficul tt o repair.Th edik eburs t causes adepressio no f the levelo f theadjacen t belt canal endangering also thestabilit y of thedike s alongside the canal.Divisio n of thebel t canal systemb ymean so femergenc yweir s limits thiseffec t toa restricte d areabu tma y causemor e localdamag e to thebel t canaldike sbecaus e of thequic kfal lo f thewate r leveli n thebel t canal. Thebel t canal dikes are covered with turf andonl y protected against stream andwav e attack at thewate rlevel .

69 A not soobviou s threat comesfro m animalactivities . Grazing cattle locallydestro y the turf on thebel t canaldike san d make aquagmir e of theoute r slopewhe n drinking from thebel tcanal . There isa growin g problem inrecen tyears ,du e toth epresenc eo f muskrats,whic h infiltrateunchecke d into theWester npar t of the Netherlandswit h itsman y smallbel t canaldikes .Muskrat sar efa rmor e dangerousbecaus e theyburro w theirhole s ingroun d adjacent toope n freshwater,whethe r dike ornot . As theentrance s liebelo wwate r levelan d the tunnels canb ever y extensive thetracin go f this threat isdifficult . Theonl ywa y of combating thisproble mno w is tocatc h themuskrats .

Thedesig no fbel t canaldike sha sno t changed verymuc h sinceforme r times,a s themajo rwor k on this sorto fdik e ismaintenance .Th ecres t musthav ea minimu mwidt ho f 1.5m ,bu t 3m isrecommende d tocate rfo r vehicular transport.Th ecres tmus tb e0. 5 to0. 8 m above theextrem e belt canallevel . Thebel t canal level isregulate d by thepumpin g stationso f thepolder s and thepumpin g stations and sluices thatdrai n thebel t canal into the seaan d itvarie swithi n certainlimits .Thoug h inth e courseo f time theinne r slopesbecam e 1:0.8 to 1:1.5 adi po f 1:3 isrecommende d as maximum slopeangl eo naccoun to f turfmaintenanc erequirements . Nevertheless thedesig nfo r ane w cross-sectionmus tb ebase d ongeo - technical investigations and calculations andwil l often showflatte r inner slopes.Thi s sometimes impliesrealignin g ditches immediately adjacent to the innerslope . Therevetment s aremad eo fwattlewor k (willowtwig s orhardwoo d strips) or, simply and cheaply,dumpe d rubble.Ofte na ree dborde r growing along thecana lban kwil l suffice toprotec t theoute rslope . Itwil lb eclea r thatregula r inspection isneede d for theupkee p of thesyste m ofbel t canaldikes . Usually this isdon eb y thepolde r and provincial authorities.A govern ­ mentalprogra m of assessment of thestabilit y and safety of thebel t canaldike s started 15year s agoafte r thefailur e of an importantbel t canaldike .Thi s isa grea t aid toth epolde r authorities,informin g themabou t thecondition s of themos t importantbel t canaldikes .

70 5. Newdevelopment s indik edesig n

Inrecen tyear s thestatistica l and economic approach todik edesig n has againbecom e atopi cfo rdabate . The inundationris ko r theprobabilit y of failureo f adefinit edik e section areespeciall y inth eforefron t of thediscussion .Th e immediate reasonfo r thisdiscussio n lies inth e ideatha t thedesig nmethod s available todat e arebase d upona desig nleve lwhic h sometimes leads tounnecessaril y high constructionexpenditure . Thepossibl e losso f areaso foutstandin g natural,cultura l or scenic interestwhic h isalmos t impossible tovalu emus t alsob e seena s expenditure. To tackle thisproble m studies areinitiate d intw odirections : a)A n assessment ismad e of the "profit"o f ahighe r levelo f security. A profound understanding mustb eobtaine d of thepossibl e damage which canb e causedb y thefailur eo f adike ,bot h interm so f money and also thelos so fhuma nlif ean d thingso f culturalinterest . Inthes e studieso f cause and consequence,historica l floodings (including the 1953floodin g of Zeeland)ar eanalyse d and scenarios of probable floodings aremade .

The aimo f these studies ist ofi x standards of safety for specific polders inrelatio n toparticula r defencerequirements .I tmus tb e realized that asafet y standard canb e formulated insevera lways , for example,a naccepte d risko f failureo f adike ,inundation , drowning or anoptima l ratio of costso f dike strengthening to profits gained froma reductio n indamag eb y flooding, (towhic h alsobelon gvariou sothe rimponderables) . Theproble mo f the (political)decisio n tofi x certain safety standards for specific areasha s still tob e solved. b) Studies aremad e toprovid e awel lbalance d designfo r aspecifi c safetystandar d orris ko ffailur e (based on apolitica l decision). Ina moder n designth e impositiono f theloa d onal l the construction elements of thedik e shouldb e arranged insuc h awa y thatal l elementsbea r thesam eris ko f failure.Fo r example:I tmigh thappe n thatmuc hmoney ,materia l and land areuse d toheighte n adik eeve n

71 though there isstil la grea tris k of failureb ypipin gbefor efloo d water actually overflows the cresto f thedike .Ou rknowledg e of the pipingmechanis m isstil l limited.Investigation s onthi sproble m have started recently.

Thefirs t step inthes e studies is toanalys e allpossibl e causeso f dikefailure .Thes e causes (aspresente d ina "faul t tree",figur e9 ) comprise four categorieso f events thatma y cause inundation: - human failure,managemen tfaults , aggressivehuma naction s such aswa ro rsabotage , - actso fGod ,extrem erainstorms ,earthquake s andhurricanes , technical failureo f structuralelements .

INUNDATION

FAILURE

HUMAN INSTABILITY FAILURE OFTH E WHOLEDIK E EXPLOSION SABOTAGE INTERNAL EROSION "ACTS

OFGOD " EROSION OUTER SLOPE OVERFLOW EROSION INNER SLOPE OVERTOPPING

Figure9 .Faul t tree

The second step ist oanalys eth edifferen t causeso f failure in aparticular category.Onl y thetechnica l failures arementione dhere :

72 overflow orovertoppin g of thedike , erosiono f thewette d slopeo r losso f stability, erosiono f theinne r slope leading toprogressiv efailure , instability of thewhol edike , instability of thefoundation s and internal erosion.

For all thesemode so f failure,th e situationwher e theforce sactin g arejus tbalance d by the strengtho f theconstructio n (theultimat e limiting state)i sconsidered . Theprobabilit y ofoccurrenc e of thissituatio n for each technical failuremechanis m canb e foundb y employingmathematica l and statistical techniques. Inthi smetho d ,Bakke r andVrijlin g (1980), the probability-density functiono f theload s and thedik e strength arecombine d (figure10) .

FAILURE

PROBABILITY OFFAILUR E

PROBABILITY DENSITY PROBABILITY FUNCTION DENSITY POTENTIAL FUNCTION THREAT RESISTANCE

TRANSFER THEORETICAL FUNCTIONS MODELS

BOUNDARY MATERIALS CONDITIONS GEOMETRY

Figure 10.Th econcep to f theultimat e limit stateo f afailur e mechanism

For thispurpos emor eknowledg emus tb e acquired concerning thecomple x problems associated with theus eo f theoreticalmodel s relating loads

73 'andstrength . Improved knowledge of the theoretical relationbetwee nwav e attack and thestrengt ho f therevetment ,o f theprobabilit y of slope stability related to thevariou s ground parameters,an d alsoo f the theoryo f internal erosion isurgentl y needed. Studieshav ebee n initiated for all these topicsdurin g thelas t1 0 to 15year s andhav ebee n intensified inrecen tyears .Th eresult so f these studies canb e applied immediately toimprov e thetraditiona lo r deterministic designmetho d until such timea smor e insight isgaine d concerning thepracticabilit y or otherwiseo f theprobabilisti c design method.

Iti simpossibl e at thismomen t topredic t theresult so f thestudie s mentioned above.Also ,whethe r orno t theprobabilisti c designmetho d for dikes isa delusio no r arealisti c conceptha s still tob e shown.

There isn odoubt ,tha t thestudie s concerning theprobabilisti c design method result ina growin g knowledge about therelativ e importanceo f thevariou s failure-mechanismsfo r thestabilit y of thewhol econstruc ­ tion.I naddition ,th eresult s of these studies enlargeou rknowledg e aboutdike s and theirbehaviou r under different conditions and also the knowledge about therisk s associated withdamag e and flooding.

References

Bakker,W.T. ,J.K .Vrijlin g 1980.Probabilisti cDesig no f SeaDefences , 17thCoasta l Engineering Conference,Marc h 24-28, 1980,Sydney , Australia;pp .2040-2059 . Wit,J.M . de,J.B . Sellmeijer,A .Pennin g 1981.Laborator y testing on Piping.Tent h Int.Conf .o n SoilMech .an dFound .Eng .Jun e 15-19, 1981,Stockholm , Sweden,pp .517-520 .

74 FROMWINDMIL LT OWIND-GENERATO R Development inPolde r Construction R.Seger s InfraConsult ,Soi lan dWate r Management Consultants Deventer,th eNetherland s

"Thething stha that hbeen , iti stha twhic hshal lbe ; and therei sn one wthin g under thesun "

1. Introduction

Thediversit y ofconstructio naspect smentione d inth ecircula r iss o extensive,tha ta choic e fromth evariou s topicsha sbee nmade .I ti s undeniable that irrigationan ddrainag esystems ,road san d shipping canals formpar to fever ypolde r involved.Howeve r themos t significant structuresessentia lt omaintai na polder ,ar edischarg estructures . Without sluicesan d especially pumping stations themajo rpar to fth e Netherlandswoul d consist ofmarshes ,lake so rsea .S olif ei nthes e regionsdepend sgreatl yo nth eperfec t conditiono f thesedischarg e structureso fwhic h therequiremen t ofreliabilit y iso f thesam e importancea s thetechnica loperatio n required.I nthi spresentatio n severalaspect so fdischarg e structureso fwhic h thepumpin g stations form theprincipl epar tar edealt hwith .

2. Sluices

Theoldes tengineerin gwork s todrai nrainfal lan d percolatingwate r fromimpoldere d areas,wer esluices .Thes ewer econstructe d ofwoo dan d brickworkan dwer esituate d at theoutlet so f smallinlan dwaterway s intoth eriver so rdirectl y intoth esea .A reliabl e protectionagains t thetida lmovement s of these awa s theprincipl e requirement ofth e inhabitants of thecoasta ldistrict sa t that time.Th enee d forfixe d water levelsdevelope d gradually overa perio d of severalcenturies .

75 Itwa sobviousl y practicalt ocombin ethes eoldes t sluiceswit h navigationlocks .

Asa resul to fth erapi d increasei nreclamatio nwork sther ewa sa comparable increasei nth enumbe ro fdrainag esite srequired . Inmos t ofthes elocation s therewa sn olonge ran yshippin gan d toimprov eth e safetyo fdik ecrossings ,th estructure swer ecovere d over (Figure1) .

Modernsluice sar econstructe d ofreinforce d concretewit hspecia l precautions against seepagealon g thestructure .Discharg e througha sluicei scontrolle db yon eo rtw oautomaticall y operatingdoors ,whic h areopene db y thepressur ehea do fth einsid ewate r levelan dclose db y thepressur ehea d ofth eoutsid ewate r level.Th edoor sar econstructe d ofhar dwoo d oftropica lorigi na sa precautio nagains t pileworm . Emergencyvalve sar ebuil t intoth estructur e forus e incas eo fa no n closureo rothe rtroubles .

Asa resul t ofgroun d settlementan d therelativ eraisin go fth emea n sealevel ,large rdischarg e structureshav ebecom enecessary .Graduall y sluiceshav ebee nreplace d bypumpin g stations.Alon g principleriver s anda tsom ebi gdischarg elocation sdrainin gdirectl y intoth esea , pumping stationshav ebee nadde d tosluices .A tlo wtid ean d lowrive r levelsdrainag eb ygravit y ispossibl eb yopenin g thesluices .Howeve r athig htid eo rhig h riverlevel sth epumpin g stationwil lbecom e operational (Figure2) .

3. Pumping stations

Asth emajo rpar to f theNetherland s cannotb edraine d bygravit y pumping stationar emos t important structures insideth epolders .Thes e pumping stationshav et ofulfi lman yconditions ,o fwhic h reliability isth emos t important.Reliabilit y canb eexpresse d inthre eway san d yourattentio n isdraw nt oth efollowin gaspects : Reliability indesign ; Reliability ofmachiner yan d itsmaintenance ; Reliability inenerg y supply.

76 cc UJ > 2. - > «j 3 ro i/i «-» > 15 .2 x a. a U r s z 3 •*- Ol o -5 «J

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78 3.1. Design reliability

During the19t hCentur ywindmill swer ereplace d bystea mengine san d paddlewheel sb yplunge rpumps ;thi scombinatio no f steamengin ean d plungerpum pwa suse d asa weapo nagains t theoldes tenem y ofth e Netherlands,referre d toI nth epast ,a sth e "waterwolf".Thi swa yo f thinkingwa sexpresse d inth efirs tdesign so fpumpin gstations ,whic h werebuil t likecastle swit htower san dgallerie s (Figure3) . Afterwards thisaggressiv eelemen t disappeared fromth edesign ,bu t aspectssuc ha ssolidit yan deffectivenes sremained .Th epresen tpumpin g stationsar econstructe d ina purel y functionalmanne ra sefficientl y andeconomicall y aspossibl e (Figure 4). Apumpin g stationi si nsom e waycomparabl ewit ha small-scal efactory ,wit h theexceptio no fth e workinghours .Th eaverag eannua ldischarg e required tomaintai npolde r watera ta nacceptabl e levelca nb edisplace d inabou t 1,000hoars , operatingwit h fullinstalle d capacity.Th elimite dworkin g time required togetherwit h thegrowin gpossibilit yo fth eautomatio no f severalspecifi coperations ,ha sresulte d inne wdevelopment s inth e constructiono fsmal lpumpin gstations .

Thetraditiona lwa yo fbuildin gpumpin g stations in-situha sbee n replaced by theconstructio no fprefabricate d pumping stations (Figure 5). Inthi scas eth ecomplet econcret esubstructure ,compose do f different parts,th emechanica lan delectrica lequipmen t andth e superstructurear esupplie d andplace db yon econtractor .A tpresen t only smaller stations,u pt o10 0m3/min ,ca nb ebuil t inthi sway . Automation,togethe rwit h thedistanc e signalizing of technicaltrouble s has resulted inth ereduce d supervisiono f smallerpumpin gstations . Most pumping stationsar esituate d at lonely spotsi nth epolde ran d areinfrequentl y attended andar etherefor ea nattractio n touninvite d visitors.Sometime s theresult so fsuc hvisit sca nb eharmfu lan da designerha s totak ethi sint oaccoun t inth edesig nt oensur epumpin g stationsecurity .

79 Fig. 3.Pumpin g stationCruquiu s

- 80- Fig. 4.Pumpin g stationKeizersvee r

81 Theaccessibilit y of thevariou scomponent so f themechanica lan d electricalequipment ,i son eo f themos t important designstandard s insideth epumpin g station (Figure 4). Badaccessibilit y isa principl e causeo f theneglec t ofinspectio nan dmaintenanc e of themai n componentso fpumpin gequipment .Secondl y itdelay sth erepai ro f damagedurin gwhic h timeth epumpin g stationi sou to forde ran dever y engineermus t tryt oshorte nthi svulnerabl e period asmuc ha sh ecan . Inadditio n thedesig nha s toinclud eprotectio nagains tclimatologica l influences.A lon glif ei son eo f theprincipl eobjective spursue db y everypolde rboard .

3.2. Machine reliabiltyan dmaintenanc e

Thereliabilit yo f thepumpin g stationi sexpresse d inth equalit yo f thepumpin gequipmen tan d itsmaintenance .Throughou t theage s understandingbetwee nsupplier san d engineersha sgrow nt oa ver yhig h standard anda sa resul t theservic egive nb y thesupplier s isbase do n givingpriorit y toal lth ekind so f repairst ob eexpecte d withpumpin g equipment.A sa resul to fthi swel lorganise d service,pum p failures canb erepaire d ina fe wday ss omos tpumpin g stationsar eequippe d withonl y twoidentica lpump so rArchimede sscrews .I nth ecas eo fver y bigdischarge s (saymor etha n1,00 0m3/min )th etota ldischarg ei s divided intothre eo rmor epumps .I nthi scas eth emetho do f transportation (byroa do r ship),determine s thedimension so f thepum p runnersan d thediese lo relectrica lengines .

Protectiono fth erunner sagains tpollutio nespeciall yagains twoode n trashi nth epolde rwate r isprovide d bytras hracks .A sa resul to f theincreasin gpopulatio n inth epolders ,th eamoun tan d thekin do f pollution isincreasing .Fo rage sth epollutio nwa smostl y soft vegetablematerials ;nowaday showeve rdomesti c rubbish,containin g plasticsan dwood , isa constan t threat toth epum prunners .Therefor e thetras hrac ki sa nimportan t parto f theequipment .Cleanin go fth e trashrac ki scompletel y automatized andmos track sar eprovide dwit ha mechanical trashremove ro rgra bbucke t (Figure6) .

82- 83 - I* VX - ^ \\\\-c>

Fig. 6. Completely automatized mechanical trushremove r

84 Inadditio nt oth eprotectio no f thepumpin gmachiner y theInspectio n andmaintenanc e ofal lmovin g partso fth emachiner ya swel la sth e electricalequipmen t Isessential .A tleas tonc ea yea ra n inspection ofth emos tvulnerabl epart so fengines ,pump san dauxiliar yengine si s necessary.Whe nth econditio no fon eo rmor epart so fth emachiner yi s unsatisfactory,th ereplacemen t of thisparticula rpar tmus tb e considered intim et opreven ta sudde nbreakdown .

Awel lcompose d schemeo fmaintenanc e isa simportan t asinspection . Thisschem eshoul db ebase do nroutin eaction safte ra fixe d numbero f workinghour san dshoul db edraw nu pb yth esupplie ro fth emachinery . Thebette rth einspectio nan dmaintenance ,th elonge rwil lb eth elif e ofth emachiner yan d themor ereliabl e thepumpin gstation .

3.3. Reliabilityo fenerg y supply

Inorde rfo ra pumpin g stationt ob ereliabl e itmus thav ea guarantee d energy supply.A nestimat eo fth emea nyearl yconsumptio no fenerg yb y allpumpin g stations inth eNetherland s togethercome st o4 5x 10°kW h andalthoug h thisconsumptio n isonl y 6%o fth etota lnationa l consumptionth edeliver yha st ob eassure dunde ral lconditions .

Theprincipl e sourceso fenerg yar eelectricit yan doi lan d iti s striking thatnatura lga s ishardl yrelevan t topumpin g station operation.A nexplanatio n forthi sma yb etha t thedistributio n networko fnatura lga sha sbee ndevelope d inth elas t 15yea rperio d and itsbranche sar eno ta sfin ea sth enetwor ko felectricity .A sa consequenceconnectio nt oth enatura lga sdistributio nnetwor kwoul db e expensive.Connectio nt oth eelectricit ynetwor k isals oneeded ,t o operate smallauxiliar ymotor san d toilluminat epumpin gstations , leading tofurthe rexpenses .

Thesuppl yo felectricit y Isguarantee db y theconstructio no fa nationaldistributio nnetwork ,constructe d insuc ha wa y that failures ofelectrict yar emostl yo fa shor tduration .Failur e of electricity supply inth eloca ldistributio nnetwor k canb eexpecte d more

85 frequently,bu t incorporationo f thepumpin g stationint oa nlatera l electrical systemwil lsolv ethi sproblem .

Pumping stationsar ei ngenera lirregula rconsumer so felectricit yan d inever ypumpin g stationa relativel y largepowe r supplymus tb e installed inrelatio n toth erelativel y shortworkin g timewhic hlead s toth eirregula r consumptiono f theloca lenerg y supply.Mos t ofth e electricity suppliers thereforehav emad e limitationsi nenerg y supply bychargin gextr adurin g themornin gan d eveningpeaks .Therefor eal l pumping stationsar eequippe d withlockin gcontact s sotha t theof f peak timeca nb ebypassed .Th ecost so fconnectin g thepumpin gstatio n toth edistributio nnetwor kar evariabl ean dar edependen t firstlyo n thelocatio no f thepumpin g stationwit hrespec t toth edistributio n networkan d secondly onth epowe rinstalled .Sometime s theconnectio n costca nb econsiderabl e and this financialconsideratio n combined with the,formerly ,lo woi lcos tmad e itattractiv e toequi ppumpin g stationswit hdiese lengines .A secon dadvantag eo f theus eo fdiese l engines isth epossibilit yo fchangin g thespee d ofrevolutio nwithi n fixed limits.Thi s speed regulation influences thedischarg eo fth e pumpsan d thepowe ro fth eengine swhic h isparticularl y importantfo r drainage intoth esea .I nthi ssituatio ntida lmovemen t causesvaryin g pressureheads ,whic hresult s invariabl edischarges .B yraisin gth e speed ofrevolution ,bot hdischarg ean d enginepowe rwil lincrease , which isattractiv e fordrainin gdurin ga risin gtide .

Acombinatio no fdiese lan delectrica lengine sma yb econsidere dwhe n pumping stationsar econstructe dwit h threeo rmor epumps .Als owhe n twoo rmor epumpin g stationsar econstructe d orhav et ob e constructed insidea polde ri twoul db ewis et oinvestigat eth ebenefit s tob e obtained fromth eus eo f twoenerg ysources .

Whenoi li suse d asa sourc eo fener*gy ,a goo d supply routeb ylan do r water isneeded .Th eoi li sgenerall y stored inundergroun d storage tanks,whic hhav et omee t environmentalpollutio nregulations .Som e pumping stationsar eprovide dwit habov egroun d storagetanks ,whic h are lessexpensiv ebu tmor evulnerable . Thetota lcapacit y ofstorag etank sinstalle d atoil-drive npumpin g stations,i sa tleas t 150%o fth eannua lconsumption .Unde rnorma l conditions 1/3 of thisquantit yha s tob eavailabl ea tal ltimes ,i n ordert omee t thereliabilit y requirements.Onl y ina stat eo fnationa l emergency isi tpermitte d tous eth ereserv equantities .Th eextr acos t attached toth einstallatio no fthi sextr astorag ecapacit yi smostl y paidb yth eGovernment ,accordin g toth eProtectio no fCivi lWork si n WartimeAct .

Therisin go fenerg y costsi nth elas t fewyear sha sresulte d ina renewed interest inth eapplicatio no fwin d energy,b ei twit hsom e diffidence.Althoug h theinvestigation s areno t finished yet,th e interimreport sregardin gth eus eo fwin dgenerator si npumpin g stations,ar eo f theopinio ntha twin d energy canb ea usefu ladditio n toelectrica lenerg y (figure7) .

Wind-generators areno toperationa ldurin gcal mo rstron gwind ,s oa connection toth eelectrica lnetwor kwoul db eessentia l tomaintai na fixedwaterleve l insideth epolde ra tal ltimes .Absenc eo f sucha connectionwoul d carryu sbac kt oth estar to fth ewindmil lperiod ,i n which thechangin gwate r levelscoul db ekep t inhan donl yb ycreatin g anadequat ewate r storagecapacit y insideth epolder ,a nundesirabl e situationtoday .

Theeffectiv epowe ro fth ewind-generato r islimited . Incompariso n withancien twindmill showever ,considerabl e improvementshav ebee n made toincreas e theefficienc y ofwind-generator s and pumping equipment;bot hth eArchimede sscre wan d theaxia l flowpum par eo fa higherqualit ya sar eth epaddl ewhee lan d theplunge rpum p today.

Both thedevelopmen t of thewind-generato r and thepréfabricatio no f small-sizepumpin g stationspromp tagai nth ealway srea lquestio nabou t centralizing ordecentralizin g thetota ldischarg eo fbi gdrainag e areas innewl y reclaimed land.A sth enumbe ro fpumpin g stations isno t theonl ycomponen t inth egenera llay-ou to fa polder ,th eanswe ri s nota neas yone .I twil lb eclear ,tha t inmos tcase sth einitia lcos t

87 M

FIG. 7 DRAFT DESIGN

WIND-GENERATOR WITH PUMP

- 88 ofconstructin g onepumpin gstatio ni sles stha nth econstructio ncost s of twoo rmore . It isals oclea r thaton ecentra lpumpin g station isalway s situated onth elowes tspo t of thepolde rcloses t toth e dike.Howeve r it isals otru etha t thesoi lexcavatio n forth e additionaldrainag e lay-outwil ldepen d greatlyo n thenumbe ro f pumping stations involved,especiall ywhe nth elay-ou t isdesigne d ina moreo rles sundulatin g terrain.Calculatio no f theinitia lcos to f somealternativ e lay-outs,i nwhic h thetota ldischarg e isdivide d over morepumpin g stations,wil lb eessentia lt omak ea justifie dan d correct choice.I tma yb eeconomica l todrai nsmal ldeep-lyin g isolated areas insideth epolde rb yseperat e pumping sub-stations.Doin gthi s willcontribut e toenerg ysavings .

3.4. Runningcost s

Inadditio n toth einitia lcos to f thetota llay-out ,ar eth erunnin g costo fth epumpin g stationsan d thecos to fmaintenanc e ofbot hth e pumping stationan d thedrainag e system.

Therunnin gcos tca nb edivide d into theenerg y costan d thecos to f manpower.Energ y costsdepen d primarily onth eannua lrainfall , percolatingwate ran d evaporation,o nth eefficienc yo f themachiner y and theconstruction ,an d lastbu tno t leasto nth eenerg y prices.Al l thesefactor sar edifficul t toinfluenc ea sth eclimatologica lan d geologicalcondition scanno tb ealtered ,th eefficienc y isth ehighes t possiblean d pricesar edictate d by third parties.Th ecos to fmanpowe r ishowever ,a subjec t ofeconom y studies,especiall ywhe ni nth elas t decadesalarie shav eincrease d tenfold andmore .Th eemploymen to f engineersan d otherpolde rworkme nha schange d insuc ha way ,tha ta sa resulto fautomatio nan dcompute r techniquesan d thedevelopmen to f automatically operating trash-rack removers,mor e timeha sbecom e available forne wactivities ,suc ha s thecentralize d cleaningo f drainsan dditche san d themaintenanc eo fmechanica lequipmen tuse dfo r thatpurpos e (figure 8). Ditchcleaning ,formerl ya lan dholder' s task isdon emor ean dmor eb ypolde rworkmen ,equippe dwit ha larg e assortment ofselecte d equipment.Fo r thisreaso nth edimension so f

89 Fig. 8.Maintenanc e ofa wate r course

culvertsar en olonge rbase do ndischarg eonly ,bu tals oo nth e dimensionso fth ewate rree dcutter .A suninterrupte d sidestrip salon g thedrain senabl eth epossibilit y foroperation swit hmechanicall y operated equipment eachsid editc hha s tob ebridge d orcovere d overa t theinle t intoth edrain .Al lthes ecosts ,mentione d abovear e significant inth edeterminatio n ofth enumbe ro fpumpin g stationst o beconstructe d ina polder .

Almost fivecenturie so finterestin g technicaldevelopment s arebetwee n theconstructio no f thefirs twindmil lan d thedesigne d wind-generator. Regarding theimprovement s ofmachiner yan dpumpin gequipment ,muc hha s beenachieve d and asa resul tbot hefficienc y and solidityar eo fhig h standardsnow .Howeve ral ltechnica lachievement swil lb ejudge d according toth erequirement s of reliability.

At theen do f thispresentation ,a tribut ei spai d totha t smallarm y ofunknow nmiller san dengine-drivers .Th e "Crugius",on eo fth eoldes t pumping stations inth eNetherland s isno wa museu man d soar eth efe w windmills thathav esurvived . Inthi sw ehonou rou rancien t technicians,wh oreclaime d polders inth epas t ages.Bu t themille ran d engine-driver,wh ob ynigh tan dda ywa semploye d onoperatin gth e windmillo rpumpings-station ,ar ehardl ymentioned .H edi dhi sjob , sometimesgrumbling ,alway sdutifully ,makin g lifepossibl e forth e majorpar to fth epeopl eo fth eNetherlands .

- 90 CONSTRUCTION ASPECTS OFPOLDER S INTH EWORL D ir.M.A .Meye r Sunecon,Paramaribo ,Surinam e

Abstract

Theconstructio no fpolder s startedoutsid eo fEurop eo na largescal e inth eCaribbea n area,wher ework swer emainl y carriedou tmanually . Thephysica lenvironmen trequire d aspecia lwa y ofreclamation . Atpresen tpolder sar econstructe d inquit e differentways ,requirin g 2 importantparameter st ob e takenint oconsideratio nagains ta grea t numbero ffactors ,viz : theconstructio nperiod ; thecost so f thepolders . Thepolde rdesign ,th ephysica lenvironment ,socio-economi ccircumst ­ ancesan dth epolitica l systemo f thecountry ,d oexercis e considerable influences uponthes e twoparameters .Example sar equote d ofth e effectso fsuc hinfluence so nth econstruction . Thedegre e ofmechanisatio n constitutesanothe r factoro fmajo rimport ­ ance. Countrywise ,wel l considered choiceswil lhav et ob emade ,i n order toarriv e atbalance d and justified ratebetwee n theutilisatio n ofconventiona lmean s andmoder n equipmenti nth econstruction .I norde r tohighligh t the effectso f thefactor snamed ,a nexampl e ispresente d ofth ecost-component so fa polde rsiz e 3,000ha ,t ob e constructed ina delta-area coveredwit h tropical rainforest .

91 1 History

The followingpresentatio n ismainl y focussed upon theconstructio no f polders in therive rdelta-area so f tropicalSout hAmerica .Sinc eth e problems tob e solved areidentica lt othos e tob esolve delsewhere , whati st ob e saidhere ,ma y thereforeb eattribute d universalsignific ­ ance. Invariou spart so fth eworl d technologies forpolde r constructionwer e moreo r lessdevelope d independantfro meac hother . Forexample ,th eendikement salongsid e thelarge rriver si nChina ,ca n be considered asth e fore-runners ofth e technology intha tregion ,o f which laterdevelopment swer ederived . Uptil lno wn ointegratio n tookplac eo fal lth econstructio n techniques developed inth evariou scountries . Thispape raim sa ta modes tcontributio n toth e establishmento fon e universaltheor y forth econstructio n ofpolders . For thestar t thepolder s inEurop e andSout hAmeric awer e considered. The emergence ofth e "polder"i nEurop ewa st oa larg e extend alsoth e resulto fprim e endikemento farea sadjacen tt oth elarge rrivers . Themethodolog y andtechnolog y therebydevelope d werefirs tuse do na large scaleoutsid eEurope ,afte r thediscover y of the "NewWorld" ,whe n Europeansattempte d tosettl e inth eGuyana's ,th erive rdelta-are a between theAmazona s and theOrinoc oriver si nth enorth-easter n section ofSouth-America . Dutchan dEnglis h colonists founded ever since the17t hcentur ysettle ­ ments along the larger rivers inthi sregion .An d thisexplain swh yth e firstpolder s constructed in thisarea ,wer eexact-copie so fwel lknow n polders foundi nth eprovinc e ofZealan d (Holland). Upt oth epresen tth eorigina llay-ou to f theearlies tZealan d polders canb e foundbac k inth eolde rplantation s alongside theSuriname , Demerary and theBerbice-rivers .However ,despit e thegrea t similarity inlay-ou tan dconstruction ,th eSouth-America npolder swer ereferre d to as"plantation" ,a nam ewhic hprimaril y referst oth epurpos erathe r thant oth e structure of thereclamatio neffort .

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i

Three important differences can be distinguished, when comparing the emergence of polders in South-America with the emergence of polders in Europe. a) The first European polders, in particular those found in the lowlands of northern Netherlands, originated as the result of the con­ struction of dams, which could facilitate overland communications be­ tween neighbouring settlements, situated on land sections above the floodline, named "terps". The construction of these communication-dams between the terps, led to the complete endikement of the lowlands between these settlements. Later on impoldering followed, which had the purpose to reclaim flood- lands, laying above the average high water mark. Special "quais" were constructed as means to accellerate the silting-up proces. In the 17th century a third polder-type emerged, the so-called "droog­ makerij", which involved the endikement and artificial drainage of marshes and lakes by means of windmills and tide-locks. The construct­ ion of this type of polders was based upon economic considerations and took to a certain extend also place, as amean s to protect densely

93- populated orintensivel y farmedarea s fromperiodica l flooding andothe r inconveniences duet ouncontrolle dwater-movement s inth emarshes .Th e famous "Haarlemmermeer polder"ca nb ename da sa n examplewhic hfit s thisdescriptio n entirely. As such threetype so fpolder s canb edistinguishe d inth eNetherland s and inothe rEuropea ncountries ,namely : polders resultingfro mth e constructiono fdam s foroverlan d communicationbetwee nsettlements ; polders resulting fromendikemen to ffloodlands ; polders resulting fromth edrainag eo fmarshe san dlakes . Thefirs ttyp eo fpolde r isth e resulto ftechnica lmeasure sprimaril y takent osatisf y thebasi c socialnee d formor e intensivefac et ofac e communicationbetwee n inhabitantso fdifferen tsettlements .Th eempol - dering oflowlan d cana s suchb esee na sa "byproduct "o fth efullfili ­ mento fa socia lneed . Theendikemen to ffloodland swa sa consequenc e ofth eincrease ddeman d forfarmlan d and settlementarea ,du et oth eincreas eo f thepopulation . Someo f theseendikement swer e alsoundertake n assafety-measures ,whic h couldprefen tth eperiodi cundesire d intrusiono fwate r intoth esettle ­ ments. Social factorsa ssuc hwer eo fprim e importancewit hrespec tt oth e emergence of thepolder s inEurope .B ycontras tthes e factorswer e entirely absenti nth econsideration swhic hgav eris et oth e emergence ofpolder s inSouth-America .Th eSouth-America npolder swer e exclusively constructedo nth ebase so fpur eeconomi creasons . TheSouth-America npolder swer eprimaril y constructed forth eculti ­ vation ofhig hpric e tropicalproduct s sucha ssugar ,cocao ,coffe ean d cotton,whic h couldno tb egrow ni nEurope . Theriver s constituted theonl ypossibl ewa yo fdirec tacces st oarea s suitable forth e cultivation ofthes eproducts .An d although theriver s offeredvas thighlan d areasupstreams ,th eEuropea n settlerspreferre d settlementi nth emarsh y downstream areas,becaus e of thehighe rfert ­ ilityo f the clay soilsavailabl e in thedownstream ssections . The choice for themarsh yarea swa s justified by the facttha tdespit e high costs forth e construction ofpolders ,economi cprofi twa slarger , because ofth ehighe rcro pyield sobtaine d from thefertil e claysoils .

94 b) Thesecon d importantdistinctio n tob emad ebetwee nth e emergence ofth eEuropea npolde ran d the South-Americanpolder ,relate s toth einvolvemen to fmanpowe ran d capitali nth epolde rconstruction . InEurop e capitalan d trainedmanpowe r forpolde r constructionswer e readily available.No ts oi nSouth-Americ aI Mos tsettler sha donly - limited funds forpolde r construction,whil emanpowe rha d tob eimport ­ ed inth efor mo fhug e slave-forces,compose d ofworker swit hn oex ­ perienceo rwha tso-eve r inpolde r construction-activities. Despite the facttha tsevera ldecade searlier ,sophisticate d equipment sucha sdredges ,excavator san d tipping cartswer e introduced forpolde r construction inEurope ,n ous ewa smad eo f theseequipment s inth econ ­ structiono fth epolder s inSouth—America .Preferenc ewa sgive nt o manuallabor ,sinc e slavelabo rwa sfa rles sexpensiv e thanth eex ­ ploitation ofsophisticate d equipments.Thes e twofactor shav e led toa n entirely newapproac hwhic hdiffer si nman yway s substantially fromth e approaches topolde rconstructio n usedi nEurop e at thattime . Themos tsignifican tdifferenc ei nthi srespec ti st ob efoun di nth e facttha tne wtechnolog y hadt ob edeveloped ,fo r theutilisatio no f cheapmanpowe r inth econstructio no fpolders ,instea do falread yknow n equipmentuse dfo rth econstructio no fpolder si nEurope . TheSouth-America n system thusfeature d capital savinga tth e expenseo f manual labor,whil e inEurop e the trend tosubstitut emanpowe rb ymean s ofcapita lwa salread ywel lunde rway . cl InEurop e thesiz eo f theimpoldere dare awa sno tdirectl y geared toon etyp eo fproduction .Impoldere d areaswer edevide d into sevetalproductio n units,eac ho fwhic hcoul d beuse d fora differen t typeo fproduction .Th eSouth-America nplantatio nhowever ,wa scon ­ structed asa singl eproductio n unit,wit ha specifi cproductio n purpose. Whatwer eth eprocedure s followed inth emanua l constructiono fpolder s orplantation s inth eNe wWorld ? Atfirs tintereste dpartie swer eallotte da parce lo fland ,wit ha give n front-width,measure di n "Rhineland Rods"alon gon eo f themai nrivers . Meanwhile itwa sthereb y alsodecide d thatth erear-boundar y ofth e parcelshoul db eestablishe d afterwardsb yth egovernmen t surveyoro f the colony.

- 95- Thecommonl y allotted front-width,measure d at 50t o7 5Rhinelan d Rods. Thiswidt hwa sestablishe d withreferenc e toth edesir et o facilitate theestablishmen to fa sman yplantation s aspossibl ealon g theriver ,sinc ea sa matte ro ffact ,th erive rwa s thesol emean so f access toth earabl eland-areas . Thedept ho f theparce lwa sdetermine d byth edrainag epossibilities . Butsinc e therewa sa n entiredependenc yupo n tidal-drainage,i twa sth e front-widthwhic h ineffec tdetermine d thetota lacreag ewhic h couldb e drained effectively,a sw eshal lse elate ron . Eachparce lwa sseparatel y impoldered.Th eimpolderin ginclude d thecon ­ structiono fdike ssurroundin g theparce lan d the excavation ofon eo r moredrainage-canals .Ofte ntw odrainage-canal swer e excavated alongside thedepth-border so f theparcel .Th epolder sthu sobtaine d arectangula r form,wit hth eshor tsid eborderin g theriver . In thiswa y thousandso frectangula rpolder svaryin g insiz ebetwee n50 0 and 1,500 "akkers" (200-600ha) „cam eint oexistenc e along themai n riversi nth eGuyanas . The areawithi n theendikemen twa ssubdevide d intodrainage-unit so f 10-15 "akkers" (4-6ha) .Withi n thedrainage-unit s ridgeswer econ ­ structedwit h alengt ho f 100-160meter san da widt ho f 8t o1 2meters . Ofcours e therewa sa lo to fvariatio nwit hrespec tt othes edimensions , due toth edifference s insoi ltype san dpermeabilit y of thesoil st ob e drained. Along theridges ,gullie swer edraw n (h=0,6-0,9m )whic hflowe d intoth e drainage canalsalon g thedrainage-unit . Because ofthei rpurpose ,drainag e canalscoul d notb euse d as"water ­ ways" for thetransportatio n ofproduct s from thefiel d toth eprocess ­ ingcente ro fth eplantation .Therefor especia l "navigation-systems"ha d tob econstructe dwithi nth epolders . Ingenera lth emai nnavigation-cana lwa sexcavate d lengthwise inth e centero fth epolder .I nthi scana la water-leve lwa smaintained ,whic h wasusuall yhighe r thanth ewater-level so f thedrainag ecanals ,i n order tofacilitat eproduc ttransportatio n bymean so fbarges . Usuallythi smai n navigation canalpopula r named "BANTAMAS"wa sgive n exceptionally largedimensions ,no tonl y tofacilitat ewate rtransport ­ ation,bu tespeciall y tob euse da sa mean s tostor ea sufficien tvolum e of freshwater ,fo rus ei nth edr y season.A ssuc h theBantama sha da

96 Figure 2.Plantatio n along arive ri nSouth-Americ a

97 functioncomparabl e totha to fth eDutc h "storagecanals " ("boezemvaar­ ten"). Inth emai ndrainag e canala tide lloc kwa sconstructed .Brick smanu ­ factured inEurop ewer euse d asconstructio nmaterial s forthes e locks. The norms takenint oaccoun tfo rth edesig no f thetida l lockwer emos t oftenbase dupo nsoun dempirica lprinciples . Forinstance ,fo rfloodland sfloode ddurin g aspecia lperio d oftime , the "sillo f thesluice "ha d tob ebuil to n lowestknow n lowtid elevel , while thewidt ho f theloc kwa sa functio no f thenumbe ro f "akkers"t o bedrained ,fo rexampl eon e footo f sluice-widthpe r 100akkers . The constructiono fsuc ha plantatio nwa scompletel y carried outi n manual labor,accordin gt oth efollowin g sequenceo factivities . Duringth edr yperiod so f theyea r theare awa scleare dmanually . The remnantso f theslashe dvegetatio nwer estore d ridge-wise fora period of4- 6 weeks. - Forth efina ldestructio no f theseremnant sb ymean so f fire,a momentwa s chosenwhereb y conditionspersisted ,whic hcoul dminimiz e allpossibl e dangerso fdamagin g theorgani c topsoilsb y theburnin g of theslashe dvegetation .Th een do f thewe tseaso nprove d topro ­ videth ebes tsuc hmoments ,sinc e attha ttim eth esoi l stillcon ­ tained sufficientmoisture . Within thesam eyea r theplante r could alreadymak e a startwit hth e planting ofhi sfirs t "cashcrop" ,i norde rt orecaptur epar to fth e land clearing costsmade . Themanua lendikemen to f theallotte dparce lwa sals ocarrie d out during thedr y season.A ver yhig h degreeo faccuratenes s andprecisio n wasobserve d indyke-construction .Especiall y the "clearing and grubbing"o fsection swithi n theconstructio n limitswer ever ycarefull y carriedout . Allorgani cmaterial s sucha sbagasse ,grass ,root san dothe r undesired materialswer eremove db yhand .Th edyke swer eerecte dwit h thesoi l speciesobtaine d fromth eexcavatio no fth ecana lo n the innersideo f thepolder-dyke . Topreven tseepag ea centercor emad eo fpur ecla ywa s firstlaid ,aroun d which the dykewa s tob eerected .Thi s centercore iscalle dth e "blinder". Allcompactio n of theadde dcla ytoo kplac eb ymean so f trampling,usin g

-9 8 Fig. 3:

CANEFIELD LAYOUTS IN GUIANA

TRANSPORT/IRRIGATION CANAL SUPPLIED FROM "SWAMP RESERVOIR

DRAINAOE CANAL TO PUMPING STATION

99 - slaves,cows ,donkey so rhorse sa sth etramplers . The locki nth edrainag ecana lwa smostl ybuil ta fe whundre dmeter s landinward fromth eriverbank .Th e lockwa sconnecte dwit h therive rb y meanso fa canal ,th e "lock creek"als ocalle d "sluicecreek" .Thi s landinward locationo fth elock swa sa safety-measur eagains twav e attackso nth eloc k aswel la sa securit y forth epreservatio n ofth e lock incas e therive r started tomeander . Thenatura lriverbank-area ,als oname d "frontland "wa suse da s residence-area.Th efrontland sha dseparat e drainage systems.Du et oth e locationo fth efrontlan dare aan dth etyp eo flan dutilisation ,muc h more complicated criteriaha d tob eobserve d inth econstructio n ofth e frontland drainagesystems . Thedeforestatio no f theimpoldere dare acoul d takeplac e duringth e wholeo fth eyear ,regardles so fth e soilcondition spresent . Theweaknes so fth esoi lan dprolonge dperiod so fexcessiv eprecipi ­ tationdi dno thav e the effectso nth epac eo fdeforestation ,whic har e atth epresen ttim eencountere db ymechanise d deforestation ofpolder - areas. Atth etim eof-plantatio n constructiononl ymanua l laborwa suse dfo r cuttingan d fragmenting oftree sa swel la sridgin go fth eslashe d vegetation.An d theslave sordere d tod othi swork ,coul d alwayswor k inth e fieldsregardles so fth eweaknes so fth e soil,the yha dt owor k on. Theconstructio n systemused ,thu sfacilitate doptima l employmento fth e meanso f construction andoptima l flexibilityo fth econstruction - operations,sinc e therewer e alson odifference swit hrespec t toth e employmento f themean so fproductio n inth econstructio n of large canalsan dth ediggin g ofsmalle rditche san dgullies . The slavesuse d forth e construction,coul dmore-ove r also immediately beemploye d forth ecultivatio n ofth ecropland . Thepac eo fplantatio n constructionwa snevertheles sver yslow . The completiono fa plantatio n ofabou t60 0h arequire d atth eaverag e tenyear so f time.Needles st osa ytha ti f theslave swer e tob epai d wages attha ttim e currenti nEurope ,al lconcern s shouldb ebancrupte d by thepolder-constructio nendeavours . There areonl ya fe wrecord s leftt ous ,containin g onlysom eo fth e manyempirica lprinciple s andpractica lexperiences ,obtaine ddurin g

-10 0 thishig h timeo fpolder-constructio n inSouth-America . Because ofth esorro w state ofou rhistorica lrecord s inthi srespect , only thephysica l remnantso fth eplantation s inth eGuyanas ,ar elef t tou sa ssilent ,fores trampante dmonuments ,i nmemor yo fa marke d era inth ehistor y ofth epolde rphenomenon .

2 Consideration forpresen tpolder-constructio n endeavours

Inth eforegoin gw ehav espen tquit e someattentio n toth emanuall ycon ­ structed "Polderso fth eWorld" .I nthi spresentatio nmanua lconstruc ­ tiono fpolder si ssee na son eo fth eextreme s fromwhic h thepolder s phenomenon canb ereviewed .Th eothe r extremei st ob efoun d inth e presentwa yo fpolder-construction ,whereb y thejo bi salmos texclu ­ sivelydon eb ymean so fheav yequipments . Inbetwee n these extremesa lo to fvaration sca nb efound ,usin gbot h manual laboran dequipments -simultaneously ,bu ti ndifferen tratios . Insparsel ypopulate d countriesmechanisatio n isofte nth eonl y alternative,becaus eo fth escarsit yo fmanpower .I ndensel yover - populated countries,suc ha sfoun d inSouth-Eas tAsia ,th eutilisatio n ofmanua l labormus tb egive nconsideranc e for largepart so fth e impolderingworks ,a sa mean st ofacilitat e thepopulatio n tobenefi t directly fromth e constructionefforts . Atth e sametim ei tmus tb eals oconsidered ,tha tth edeman d forreadil y cultivaleable croplandsi sals oextremel y largei nessentiall y thistyp e ofcountries ,whic hma ywel l leadt olimitation si nth eutilisatio no f thevas tamount so fmanua l laboravailable ,i nfavou ro f theoptima l utilisationo fequipment s forcertai nsection so fth e job,a sa measur e tospee du p theconstructio n operationsan da sa measur e to satisfyth e need forfarmlan d inth eshortes tpossibl eperio do ftime . Butregardles s ofth ekind so fth econsideration s tob e takenint o account,decision s concerning theinvolvemen to fmanua lworker svi z equipments,wil lalway shav e tob emad ewit hreferenc e toa contex to f soundprinciples ,t ob eobserve d inorde rt oobtai noptima lrealisation - efficiency atth elowes tcosts . Inthi s section arevie wi smad eo f themos timportan telement sa tpla y incontemporar ypolder-construction .Th e factorst ob econsidered ,wil l

101 be analysed,usin ga sbasi c comparativeparameters : a. THE PACE OF CONSTRUCTION,- b. THE COSTS PER AREA-UNIT. Needless tosa ytha tth eanalysi san d comparisonspresente dher ear e both farfro m complete and farfro mexhaustive .

2.1 Thephysica l environment

Itseem squit ejustifie d toassum e thatal love r theworld ,th earea st o beimpoldere dar e composedb yland swhic har emor eo rles spermanentl y submerged.A sa consequenc e thesoil so fthes e areasar emostl yno t fully consolidated andma yofte nb equit eyoung . Theborder so f theare at ob eimpoldered , shouldb edetermine d onth e baseso fa soun danalysi so fprevalen thydrologica lconditions . Strictobservatio n ofth ehydrologica lcondition s isth eprim e andfore ­ mostimportan trequirement ,t osecur e aprope rpac ean dleas tcost so f the constructionactivities . The randomobstructio n ofth enatura ldrainag eo fsurroundin g areas,ma y cause a loto f complexproblem sbot hdurin g theconstructio nperio dan d afterwards. Alleffort s shouldtherefor eb emad e toobtai nth emos taccurat ein ­ sights concerning thenatura ldrainag e system and the topographical and vegetational characteristicso fth eare ab ymean so faeria lphotograp h analysis. Inan y caseprio r toth einitiatio no fth epolder-constructio n a thorough appraisalmus tb emad eo fth efollowin gfactors : Climate :Th ecours e ofannua lprecipitatio n and theidentifi ­ cationo fdr yan dwe tperiods . Hydrography :Th e locationo fswamps ,cree kan drive rcourses , gullies and tidaleffects . Soil :Topography ,presenc eo f softlayer san dperviou s soils,possibl epresenc e ofaci d sulfatesoils . Vegetation :A nanalysi so f thevariou stype so fvegetatio nan d vegetation layers,t ob e categorized forexampl ein :

102 :- dense forest medium forest scrubVegetatio n herbalvegetatio n andgrasse s Accessibility :Al lpossibl emean so facces swil lhav et ob esurveye d withemphasi so n theanalysi s offactor so flogis ­ ticalsignificance . Management :Analysi so fanticipate d social,economi can dtechno ­ logical situationswhic hma y affectbot hpolder - construction andpolder-maintenanc e activitiesa s wella sdecision s concerningcentralise do r decentralised control.

Although the factors justmentione dma ysee mrathe r self-evidentaffair s inpolder-construction ,i tappear si npractic e thatthe yar eofte nin ­ sufficientlyo rno ta tal lobserved . Water-annoyance during theconstructio nan d subsequentsaggin go f machines,logistic sproblem saffectin gpersonne l transportations,fuel s andfoo dsupplies ,an dpoo rworkin g conditionsdu et oincorrectl y selected campsites areonl ysom eo fth eman yproblem s tob e faced,a sa consequence ofneglectin g theforementione dfactors . Quite often theneglec to fa prope rapproac h towards thefactor s mentioned alsoresult s inwron g choiceso fequipment s- choosin g either toosmal lo rto olarg emachines . Suchneglect s leadt oba dplanning ,whic hi nman y instancesresult sint o theescalatio no f construction costsb yhundred s ofpercents . Extensive confrontationwit h suchproblem san d cost-escalations,i son e ofth emos toutstandin g aspects ofpolder-constructio ni nth edelta - areaso f countries asBrazil ,Guyana ,Venezuela ,Thailand ,India , Bangladesh,Birma ,Vietna m andIndonesia . Itwoul db eerroneou st othin ktha tth e factorsname d areno to ro fles s relevance forpolder-constructions ,whic h takeplac ei na somewha t differentphysica l environment.Th erelevanc epertain s toal lth ekind s ofphysica lenvironment s ofpolder-construction . Andt opoin tou tanothe r exampleo fa physica lenvironmen t towhic h these factorsals oapply ,referenc e canb emad e toth eHachir oGat o polders inNorther nJapa nan dt oth epolder si nth ePeople sRepubli co f

- 103 Figure 4. Aerial photograph of flood lands

Fig. =: Rainfall and évapotranspiration in Tropical tuamd regions

100 — --

J F M A MJJASON D Ramfall Paramaribo _ ._ Pot-évapotranspiration

104 *£*K*.**V,H^-

Figure6 . Deforestrate d area

Figure7 . Equipmenti n rainyseaso n

Figure8 . •J*"? •i g Logistics

105- (North)Korea .I nbot h countries thepolder-construction s were carried outi ninlan dsea-areas . Thewate rbalanc e inrelatio nt osalinity ,constitute d themos t important factori ndeterminin go f thesiz ean dboundarie so fthes e polders,whil ea sothe rprim e factorst ob etake nint oaccoun ti nth e construction ofthes epolder sth efollowin g canb enamed : - permeability of thesoils ; - desalination; - soil compaction andseepag eo fsoils . Thetw otype s ofphysica l conditionsmentione d namely: - thedensel y vegetatedmarsh y tropicaldelta-areas ,an d - inland-seas, canb esee na stw oextrem e typeso fphysica lconditions ,whic hdespit e theirdifference s require the totalobservanc eo fal lfactor snamed .

The carefullexaminatio n ofth e conditionspresente db y thephysica l environment,i sals oo fmajo r importance forth e choiceo fpolde r design,th echoic eo fconstructio nmethod s andfo rth edeterminatio no f thedegre eo fmechanisatio n ofth econstructio noperations . Inth edelta-area sprope rmechanisatio no fth eoperation sma yb ebes t pursuedb y theinvolvemen to f conventionalmachine s such asbulldozers , draglines andhydrauli cexcavators ,whil e inth ecas eo finland-sea s the maininfrastructur e canb ebes trealize db yth einvolvemen to fdredges .

Fora prope r approachi ti so fcours e necessary totak eals oothe r aspectsint oaccount ,whic h areno tdirectl y related toth ephysica l environmento fth epolde r area.Som eo fth esocio-economi c aspectst ob e studied forthi spurpos ewil lb ereviewe db y thenex tsection .

2.2 Socio-economic aspects

Allove rth eworld ,th econstructio no fpolder swil lhav et ob e preceededb ya nanalysi so fth esocio-economi c conditions,prevalen ti n thecountr ywithi nwhic h the construction ist otak eplace . Substantialinfluence s areexercise dupo n thepac eo f construction activities and thecost so fth epolder-constructio n byfactor ssuc ha s:

106 localexperience s inpolder-construction ; distributiono ftechnica lknow-how ,skill san dexperienc e inmachin e operatingan dmaintenance ; employment conditions andcustom so femployer s andemployees ; wage levelsan dwag estructure ; time-usepattern so f skilledan dunskille dmanua lworkers . Iti so fprim e necessityt oobtai nreliabl edat ao fthes e factorsi n ordert ob e able tomak e aprope rassessmen to fsocia lconditions ,whic h affectver y seriously both thecost san dth eduratio no fth epolder - construction,a swel la smatter ssuc ha sth edegre ean dleve lo f mechanisation tob e applied inth econstruction .I ti stherefor en o luxuryt ohir e awel ltraine d socialscientis twit h considerable field experiences tod othi sjob . Incas eth eloca lexperienc eprove st ob elimite d tomanua l operations only,o rt ooperation sinvolvin g traditionalequipments ,a progra mmus t bemad e for thecompletio no fth eproject ,whic hha s takenthes e realitiesint oaccoun ti nth eselectio no fth e levelo fmechanisatio nt o be observed. Ifth epolde rwoul db econstructe d inprett ymuc h thesam ewa ya sdon e by thepopulatio nu pt otha ttime ,onl yrelativel y smallacreag eo f arable landwoul db ereclaime d ina give ntim eperiod .Th e satisfaction of thenee d for farmlandwoul da ssuc hrequir e anexcessivel y long periodo f time.B y contrasta highl ymechanise d approach couldresul ti n aver yhig h levelo farabl e landrealisation .Bu ti ti sno texclude d thatsuc ha napproac hdoe sno tconcu rwit h theinterest so f the local population,becaus e ofth evas tnumber so fmanua lworker s thatwoul d have tob epu tof fside . Programplannin g forpolder-constructio n assuc hinvolve squit e alo to f exercises incompromisin g the twosocia l interestsnamed ,i nrelatio nt o factors sucha spac eo fth eoperation san d levelo fmechanisation . Solutions forsuc h "conflicting interests"ma yb e foundb yvariou s forms ofdivisio no f labor,linkin gth einvolvemen to fmoder nmachine s toth e constructiono f larger andmor e comprehensive worksmeanwhil e assigning thedetailment s ofth econstructio n tomanua lworkers . Such approachesma gpossibl ymak eth eachievemen to fth ehighes tleve l ofmechanisatio n illusive froma technica lpoin to fview .On emus thow ­ ever consider thati n thiswa y asociall y acceptablebalanc e canb e

107 found,providin gbot h the timely completiono fth econstructio no nth e onehan d andampl eopportunitie sfo remploymen tan d trainingo floca l workers onth eothe rhand . Inselectin g themachine st ob einvolve di nth e construction,attentio n mustb epai d tosuc hfactor s aspost-constructio n exploitationo fth e equipment,fo rexampl ei nmaintenanc e activities andpossibl y alsoi n otherconstructio n activities,t ob epursue d in forthcoming timesb yth e country. Finally inquires shouldals ob emad e todetermin ewhethe r ornot ,an di f sot owha texten dworker sneede d forth econstructio nwil lb eavailabl e during theseason smos tsuitabl e forth erealisatio n ofth econstruction . Itma ywel lb etha tthes eperiod s co-incidewit h otheractivitie so fth e population,suc h asplantin go rharvestin go fcrops ,dwellin g construction andth elike .

2.3 Therelation sbetwee npolde rdesig nan dth epac e andcost s ofpolder-construction s

Thetopograph y ofth eare at ob e impolderedconstitute s thebase sfo r thepolde rdesign .Bu tbecaus eo ffactor s sucha sth epac eo fcon ­ struction andth ecost spe r area-unit,othe r factors,amon gwhic hth e followingmus t alsob e takenint oaccount . - dimensions ofcanals ,conduit san dparcel-ditche shav et ob e standarized asmuc ha spossible ; cross-profiles ofcanal setc .hav et ob eatterne d toth emachine st o be used,s ot osecur e theobtainmen to fth ehighes t levelo f efficiency; thevolum eo feart hspecie sneede d forth econstructio n ofdam san d road foundations,ha st ob euse da sdeterminin g factor forth e establishmento f thedimension so fexcavations . (Thisma yresul ti n dimensions forth evariou stype so fexcavation swhic h areno ti n accordancewit h theoutcome so fhydraulogica l calculations.) irregularly shapeso fparcel smus tb e avoided; (mechanised)cro p productions requireregula rshaped-preferabl yrectangula r parcels,t o beobtaine db ysomewha tmor eo f land-levelling if suchi snecessary .

108 The finaldesig no fa polde ri stherefor eobtaine db ycross-comparin g of theadvantage s anddisadvantage s ofth e followingprinciples . a) Size of thesmalles tpolder-uni t

Thecost spe r area-unito fth epolde r increase relatively toth e average-costst oth e extend thatth esiz eo fth earea-unit si sdecreased . Thisi sdu et oth e considerable increase oftertiar y infrastructure, which also limitsi.e .decrease sth epac eo fth epolder-construction . Basicallypolder so fth esam esiz e requireidentica lperiod s oftim efo r construction.Difference si nconstructio n timear eprimaril y causedb y differencesbetwee nth eparcellin g systems. Thesmalle rth epolde rth elarge r the costspe rarea-unit . The costspe rarea-uni t (parcel)o fth epolde rincreas erelativel y to averagearea-uni tcosts ,t oth eexten d thatth esiz eo fth earea-unit s isdcreased . This isdu et oth econsiderabl eincreas e oftertiar yinfrastructure , which increases construction-costsan ddecrease sth epac eo fth epolder - construction. b) Overlandversu snavigationa lwithin-polde r communications

Achoic eshal lb emad ebetwee n aroadssyste m andnavigatio ncanals ,a s meanst ofacilitat e thehaulin go fgoods/product s toan dfro mth e parcels. Incas eo fchoosin g fora navigatio nsystem ,thi swil lmeanwhil e also requirea choic e tob emad eou to feithe r drainageo rirrigatio ncanals , tob emad esuitabl e forthi spurpose .I nconsiderin g thesealternatives , comparative evaluationshav et ob emad eo fth efollowin gfactor s: - construction andmaintenanc e costso froads ; costs ofcana ladaptation ssuc ha sraisin go fquai s andbridges , constructiono fduct s; enlargemento fth ewe tprofil eo fcanal san dsubsequen textr a excavationcosts ; - .purposeo f thepolde r (smallholding spolde ro r singleestat epolder) .

- 109 c) High level or low level water presentation

The water level to be maintained in the irrigation-canals, will in­ fluence the construction and exploitation costs of the polder to a con­ siderable extend. High level water presentation requires higher dams. This implies that more earth will have to be excavated than necessary, according to hydraulogical calculations. For a low level water presentation less excavating is required because the profile to be constructed will be in closer approximation to the outcomes of the hydraulogical calculations.

A second consideration is the degree of efficient water-utilisation, since the farmers will waste a lot of water in case of high level presentation, which is in contrast with the utilisation if a low level presentation ismaintained , whereby pumping costs are to be paid by the farmer. In the exploitation phase central pumping and high level presentation may prove tob e far less expensive than low level presentation and individual pumping. In the last case the farmers themselves will have to account for the pumping costs,whic h in effect only implies the shifting of some of the costs.

2.4 Political factors

Next to the various,physical , technical and socio-economic aspects the design and construction of polders is also substantially influenced by various types of political decisions,o f state and local governments. In the densely forested delta-areas the government will have to decide whether or not the farmers will be allotted either readily cultivaleable or partly orwholl y forested parcels, to be cleaned up by the farmers ind iv idually .

Next to the fact that about 15 to 20 percent of the investment costs are transferred to the farmers,b y allotting them partly or wholly forested parcels, other disadvantages of individual land clearing must also be considered. To name a few:

110 Theperio d of landimproductivit yo fth eimpoldere d areawil lb e extendedsubstantially ,sinc e the farmersca nonl y startwit hth e clearingafte r the completiono fth econstructio n andafte rcomple ­ tiono f theprocesse s ofparcellin g andallotment .An d thosepro ­ cessesma y takea lo to ftime ,mainl ybecaus e ofextensiv epolitica l deliberationsproceedin g them. If thepolde ri sdelivere d duringa perio do funfavourabl eweathe r conditions,th e farmerswil lhav et opostpon e theclearin g activities forrathe rlon gperiod so ftime . - Thecontracto rha sth eopportunit y tosecur eth elan dclearin g ina highly centralizedway ,th econstructio nperio dwil linclud esevera l suitable seasons,facilitatin g thecontracto r tocommenc ean d continue the clearingoperation saccordin g toweathe rconditions . Theclearin g costsmigh tb ehighe r inindividua l clearingo fparcel s since the clearingha st ob epursue db ymean so fworker swhic har ea t thetim eo fclearin gals omuc hi ndeman db y other activities (harvesting etc.). Individual clearingactivitie sma yresul tperiodicall y inover - demands forrelativel yscarcel y availablemachine s andothe r equipments. - Thefarmer s loosea tleas ttw ocro pseason si.e .tw ocro pharvests . Theinteres tperio d ofth einvestment s forclearin g isextende dwit h atleas ton eo rtw oyears . Thedecisio n toallo teithe rforeste do rcleare dparcel st oth efarmers , iso fcours e influencedb yman yothe rpolitica lan d socio-economic factors. Nextt oth e financingterm sb ywhic h fundsar eallocate d forpolde rcon ­ struction,i ti sth eprim esocio-economi c roleo fth epolder ,whic hmus t besee na sa majo rimportan tfacto rwit hsubstantia l effectsupo nth e decision tob emade ,concernin g theclearin gcondition s ofparcel s tob e allottedt ofarmers . Ifth epolde ri sconstructe dprimaril y asa mean s forth erapi d solution ofnationa lfoo dconstraints ,i tappear st ob emos trecommendabl et o allotreadil y cultivaleableparcel s toth e farmers.I nthi swa yn o harvests arelost ,whil e theeffect so fth einvestmen tca nb emad e readily sensible tomajo rsection s ofth epopulation .

-Il l- Incountrie s suffering fromforeig ncurrenc y constraints,allotmen to f forestedparcel sma yb e seena sth eonl ywa yt ofinaliz e thepolder - construction,o ra sa mean st osav esom eo fth e foreigncurrencies , otherwiset ob euse d forth epurchasin g offuel san d spareparts for machines. The considerations shouldno tb e limited toonl y macro-technical financial andsocia laspects . Thedecisio n concerning theallotmen to feithe r forestedo rcleare d parcels tofarmers ,ha sals ot otak eint oaccoun tth e socio-economic positiono fth eindividua l farmersa swel la sth esocia leffect so feac h ofthes e twoalternatives ,i norde r toavoi dproblem ssuc ha sth e following: Ina nIndonesia n landreclamatio nproject ,farmer swer e allottedrice - parcelsstil lcontainin g stumpsan d trunkso flarg etrees ,leavin gonl y a sparse amounto fope nlan dfo rth ecultivatio n ofrice . Because ofth ealmos tstil lto omodes tparcel sallotte di nthes e regions thistyp eo fallotmen tcoul d easilyhav ebrough tth e farmers existence intoperil ,sinc e thene tcultivaleabl e areao fth eparce lwa si neffec t reduced farbelo w theminimu mproportion s oflan dneede d togro w sufficientric e forhi spersona lsubsistance .Meanwhil eh ewa sals o left with thealmos timpossibl e task ofremovin gth etrunk san d stumps,wit h nomean s orwhatso-eve r available forthi spurpose . In someo fth e landrefor mproject s ofth eRepubli co fColombia ,onl y themai ninfrastructur ewa spu ti na nare aallotte d tofarmers . Asa consequenc eo f theabsenc eo fothe rprovision sth efarmer swer e unable toproduc ebeyon d subsistancelevel . Inothe rproject s oftha tsam ecountry ,farmer swer eallotte d readily cultivaleableparcels ,whic h enabled therapi d ascertainmento fa decen t levelo fliving . Itmus tb eclea r thatsuc hinconsisten tallotmen tpolicie s caneasil y resulti n theemergenc e ofsocia ltension sbetwee n themor ean dth e less favoured groups offarmers . Thenatur eo fth eterm sb ywhic h funds aremad eavailable ,als o exercises considerable influencesupo npolitica l decisionswit h respect toth eapproache s tob e followed inth e realisationo f land reclamation projects. This statementca nb ever y clearly illustrated by acompariso n ofth e

- 112- policies followedb y the cooperative Republico fGuyan aan d thosechose n by itsneighbour ,th eRepubli co fSuriname . Land-reclamation inGuyan ai salmos tentirel y financedb ymean so ffund s obtained atrelativel y highinteres trate s frominternationa l financing institutes.I nSurinam eth e land-reclamations arefinance d outo ffunds , donated freeo fan y chargeb y theGovernmen to fth eKingdo m ofth e Netherlands- theforme rrule ro fthi scountry . TheGuyanes e Governmentha sexplicitl y chosenfo ra napproach ,whic h secureshig h speed,efficien trealisatio no fth epolders . Two large land-reclamationproject sar e executed atth esam etime ,eac h controlledb y aseparat e specialappointe d authority,wit h fullfledge d decision-an doperationa lcontrol . TheM.M.A.-authorit yi scharge dwit h thereclamatio no fa nare ao f 50,000ha ,situate dbetwee n theMahaica ,th eMahaicon yan d theAbarr y rivers.A tth esam etim ea secon d largepolde r- th eBlac k Bushpolde r- isconstructe d inth eare abetwee n theCanj ean d theCorantyn eriver , underdirec tcontro lo fa differen tGovernmen tauthority . Inth eM.M.A.-project ,th ereclamatio nwork sar ecommissione d toon e contractor supervisedb yon econsultant .Bot h areoblige d tocomplet e the total land-reclamationwithi n theshortes tpossibl eperio d oftime . The approach resultsi nsimpl ean dver ystraigh t forward relations between theauthorities ,th econsultan tan dth econtractor ,meanwhil e alsosecurin ghig h speedan defficien tcompletio no fth econstructions . Inm yopinio n theGuyanes eapproac h appearst omak e alo to fgoo dsense . By contrast toth eGuyanes ehig hspee dconstructio nendeavour ,th e approach appliedb yth eSurinam eGovernmen ti nth erealisatio no fth e "Multi-Purpose Corantyne CanalProject "- MC P- ,feature sa continuousl y ongoing concern,t osegregat e theconstructio nint oa sman y smallitem s aspossible ,t ob e commissioned toa sman y aspossibl econtractors . Controli sal lbu tfirml yestablishe di nth egovernmen t agency charged withth ecoordinatio n andsupervisio n ofth econstruction ,sinc esevera l othergovernmen tinstitution s arestil l lefta voic ei nth edecision ­ makingprocess . Duet othes e factors thepac eo fproject-realisatio n isslowe d downcon ­ siderably andbecaus e ofth eto oslo wan d toosluggis hpac eo f realisation,constructio n costsescalat e substantially.

13 TheSurinam eGovernmen tha sno wreduce d thetota lare at ob e impoldered asa measur e tokee p theprojec tcost s inbalanc ewit h theavailabl e capital funds forth eproject . With referencet oth e forementioned aspectsan dsituations ,i tma yb e stated thatth econstructio n ofpolder si nth edevelopin gworld ,ha st o takeplac ei nsuc ha wa y thata readil y cultivaleablepolde rca nb e obtained,b yobservin gal lfactor so finfluenc eupo nth ecost s andth e paceo fth econstruction . Thisobjectiv ewil lhav et ob eenforce db yal lcircumstance s andregard ­ lesso fth eway s inwhic h andth econdition sb ywhic h fundswer e obtained forth econstruction . Infina lsom ebroa d remarksma yb emad e concerningth e executiono fth e constructionactivities .Mos timportan ti nthi srespec ti sth echoic e betweeninvolvemen to fth eloca lpopulatio no nth eon ehan do rth ein ­ volvemento fa foreig n contractoro nth eothe rhand . Asth econstructio no fpolder s requiresa ver yspecifi cknow-how ,i tma y berecommendabl efo rcountrie swit hn oexperienc e inpolder-constructio n tostar twit h foreigncontractor s rather thantakin g anotherapproach . After theinitia ltransfe ro fknow-ho w joint,venture sma yb e considered asa nex tste pi n theswitc h toth econstructio no fpolder sb y local contractors. Atlas tbu tno ta tleast ,muc hattentio nshoul db egive nt opromot eth e willingnesso fth efarmer st oadap tthemselve s toth ene wproductio n and livingcircumstances .

3 Financialaspect so fpolder—constructio ni na densel y forested tropical delta-area

Inconclusio n ofthi spresentatio n anexampl ewil lno wb epresente do f the construction ofa middl esize dpolde ri na densel y forested,marsh y tropicaldelta-area .Th eexampl e isfictitiou san di sonl ymean tt o illustrate thecost sinvolve di npolder-construction .Th e assumedpolde r measures 5,000-6,000meters . Allto oofte ni toccur sa tth ecommencemen to fsuc hprojects ,tha tn o more thanincomplet e costsar epresente d andtha tth e"disappointments " asmentione di npreviou s chapters,i nfac td oresul tint omor e extensive

114- financialconsequence s thanw aassume da tfirst . By thefollowin g table arevie wi spresente do fth ecost s forth e realisationo fa polder ,generall yname d "constructioncosts" .

Tableo ftota lprojec tcost si n%

1 Constructioncost s 100 % 2 Contingencies à (15%) 15 % Sub-total 115 % 3 Engineering costs (13%) 14,95% 4 Legalan dadministrativ e costs (3% l 3,45% Sub-total 133,40% 5 Financing costs (3% ) 4 % Sub-total 137,40% 6 Interest during construction (6% ) 8,24% (interesti n1 year l Totalprojec tcost s

The tableshow stha tth e costs forth eso-calle d "additionalelements " canamoun tt oalmos t5 0percen to fth econstructio ncosts . Thesiz eo f theso-calle d "contingencies"depend supo nth estag eo fcon ­ structiono f theprojec ta tth etim e thatth eestimat ewa sprepared . Atenterin gint oth efinancin go ra tth eapplicatio n for development aid,referenc eshoul db emad et oth eabov ementione d cost-alignment, whichmus tb e seena sa naverage ,calculate do nth ebase s ofdat a obtained froma large rnumbe ro fpolder-projects . Foreac hprojec ta separat eanalysi smus tb emade ,t odetermin eth e extendo fapplicabilit y ofth e itemsinclude dint oth ecosts-alignmen t mentioned,becaus e thetabl epresente d assumesprojec trealisatio nb ya private contractor. Amor eextende d eleborationo fth e "polder-construction costs"show s that thereals oexis tver ymarke d differencesbetwee n the "directcosts " and the "finalcosts" . The "directcosts "ar ename d "netcosts "i nth efollowin gan dca nb e specified asfollows : - generalpreparations ; - plottingcosts ;

115 endikemento ftota larea ; clearance oftract san dexcavatio no f conduits; roadconstruction s (unpaved); primary engineering constructions; secundary engineering constructions; parcelling includingdeforestation . Tothes ene t (direct)costs ,th egenera l costs forth eexecutio nafte r contractinghav e tob e added.Th e followingreference sma y serve aguid e linesfo rth ecost st ob e considered inthi scontext .

rtem Percentage/costs netcost s 100 - generalcost s 6.7 - construction costs 6.0 managementcost s 3.2 - mobilisation,demobilisatio nan dtranspor - 8.3 tationcost s Sub-total 124.2 Risks andprofit s (assumeda t 15%)" 18.6 TOTALCOST S 142.8

Inth epreviou stabl e the "construction costs"wer e assumed at100% ,bu t in relation toth ene tcosts ,constructio n costs doamoun tt o1.4 2 times theestimate .A ssuc hth e finalpictur e ofne tcost sreveal sth e following

Netconstructio n (nettoaanleg ) 100 % Netdirec tcost s (construction costs! 142.83% Project costs (1yea rconstructio nperiod ) 208.01%

Theenginee ri stherefor e compelledt ofocu shi s attention atal ltimes , upon thepreparatio no faccurat e cost-estimates,whic hhav e topresen t a complete and correctpictur e ofth etota lcosts ,i norde r toavoi dhi s principalt ob e confrontedwit hembarrassin g surprises,a tth eda yo f project-delivery .

- 116- The followingcosts-estimat e canb epresente d forth eimaginar ypolde r size 3,000ha ,t ob e constructedi n adensel y forested,marsh y tropical delta-area. The costsar ebase d uponexperiences ,obtaine di nric epolder san d bananapolder-constructions .

Polder-constructioncost si n198 2 (example!

Item Descriptiono fwor k Costspe rh a (gross) inUS $ 1 Generalpreparations ,surveyin g etc. 250.- 2 Endikements 250.- 3 Tractclearin g andcondui texcavatio n 750.- 4 Roadpavement s (upt oth eparcels ) 750.- 5 Primary engineering constructions 1,000.- (irrigationl 6 Secundaryengineerin g constructions 750.- (culvertsan dbridges l 7 Deforestation, levelling,clearing / 1,500.- grubbing A Construction costs 5,250.- B Projectcost sincludin g financing, s^so.-1 supervision,interes t24 % 1 Multipliedb y 170.36du et oth eaccumulatio n ofinteres tdurin g thefou ryea r constructionperiod .

Fromth epreviou s tablei tappear stha tapproximatel y50 %o fth ecost s forth e construction ofa ne wpolde ri sabsorbe db y the deforestation ofth earea . These costs areextremel y sensitive foreffect so fth e factorsmentione d in chapter 2. The remaining works such as engineering construction, road pavings are less affected by some of those aspects.

Note

1 1 R.R. = 3,6764 m

117 - References

Benjamin,dr .H.D . andJoh .F .Snelleman ,1914 ,Leide n Encyclopedie vanNederland sWest-Indi ë Consortium M.C.P.,1978 ,"Multi-Purpos e Corantijn-Projekt, VoorbereidingFAS EI ConsortiumM.C.P. ,1982 ,Advieze nB1-B8 , definitiefprojek t F.A.O.,1988 ,Surve yo fth eCanj eReservoi rSchem e Guyana Lier,prof .R .van ,1971 , Samenleving inee ngrensgebie d Rodney,Walter ,1979 ,Guyanes e SugarPlantatio ni nth e late 19th century SurinaamscheHistorisch eKring ,jul i1968 , UitSuriname' shistori e SurgromaN.V. , 1977,Vooronderzoe kbevloeiingsmogelijkhede n Regio2 - Surinam e Teenstra,M.D. ,1833 ,D e landbouwi nd ekoloni e Suriname Traa,mr .A .van ,194 6 Suriname1900-194 0

118 AGRICULTURALASPECT S

- J. van der Veen. Agricultural aspects inpolde r areas inth eNetherland s - H. Brommer. Agriculture and foodproductio n inpolde r areas

- 119- 120 AGRICULTURAL ASPECTS INPOLDE R AREAS INTH ENETHERLAND S J. vande rVee n Landbouwschap TheHague ,Th eNetherland s

I amgla d tohav e thisopportunity ,a sChairma no f theLandbouwschap , totel lyo u something about theagricultura l aspects ofpolde rarea s inthi scountry .Firs t ofall ,I thin k Iough t totel lyo u something about theLandbouwscha p itself.

TheLandbouwscha p

TheLandbouwscha p isth epubli c cooperation ofth e agricultural employers' and employees'organization s inth eNetherlands .W ehav e three employers'organization s - thebigges t isth eNetherland s Catholic Farmers and GrowersUnio n (K.N.B.T.B.),the nther e isth eGenera lRoya l Netherlands Agricultural Committee (K.N.L.C.)followe d by theProtestan t Farmers'an d Growers'Unio n (C.B.T.B.),o fwhic h Imysel f amals o Chairman.Aroun d 80%o f the 140.000farmer s and growers inthi s country are affiliated toon e of these organizations.Th e agriculturalem ­ ployees' areorganize d intw osectora lunion s- th eFoo d Workers'Unio n F.N.V.an d theFoo dWorkers 'Unio nC.N.V . *' These5 organization s have astatutor y organization -a scentra l agri­ cultural organization,recognize d byDutc hLaw .Th eBoar d ofth e Landbouwschap ismad eu p ofrepresentative s from all5 organizations . TheChairmanshi p atpresen t rotatesbetwee n theChairma n of thethre e farmersorganizations .Th emember s of theagricultura l organizations are perfectly satisfiedwit h thisuniqu efor m ofcooperation . TheLandbouwscha p acts asa mouthpiec e forDutc h agriculture asa whole,an d it is indeed recognized assuc hb yGovernmen t and Parliament.

*)F.N.V .= th eFederatio n ofNetherland s TradeUnio n C.N.V.= th eChristia nNetherland s TradeUnio n

121 Thepositio n of farming inth eNetherland s

Thisbring sm e toa fe wremark s about thepositio n of agriculture in theNetherlands .Ou rcountr y issmall ,densel ypopulate d andwel lknow n for itswindmill s and cheese.It s total areao f agricultural landi s about 2millio nha . Every year someo f that areai s lost toprovid e land forothe rpurpose s sucha shousin g and recreation,an d somei sdesignate d asnatur earea . This lossamount s toabou t 10.000h aever yyear .

In 1950n o fewer than 17%o f theDutc hworkin g populationwer e employed inagriculture .Toda y that figureha s fallen to 6%. Nevertheless thesignificanc e ofth eagricultura l sector forth eDutc h economyha s increased. Inspit eo f thereductio n inth eare ao f agricultural land and thefal l innumbe r of agricultural holdings -w e nowhav e 145.000- agricultura l outputha d risen substantially.A considerable part of this outputha s tob e sold abroad.

Letm e giveyo u afe wfigure s toillustrat e this. In 1981 theNether ­ lands exported agricultural productswort h 31milliar d guilders.Thi s increased thesurplu s on theagricultura l tradebalanc e to 14.7 milliard guilders.Thi s contribution toth eDutc h economymatche s that madeb y theexport s ofnatura l gas.Dutc h agriculture is small-scaleb y nature.Th e average sizeo f theholdin g -excludin ghorticultur e -i s 18ha .Thi s small-scale character isoffse tb y the large-scalenatur e of theancillary ,manufacturin g andmarketin g sectors.I nthi sstructur e of small-scaleholding s andhighl y concentrated marketing liesth e great strength ofDutc hagriculture . The agricultural land isuse d very intensively.Th ene t addedvalu epe r ha of agricultural land isalmos t 4.000guilders .Tha t isove r 35.000 guilders forever y agriculturalworker .An d that intur n is20.00 0 guildersmor e thanth eaverag e figure for theEEC .

Since the 1950seac hh a of agricultural landha sbee nuse d toa n increasingly intensive extent.Fo r arable land,th epercentag eo f labour-intensive crops- potatoe s and sugarbeet s- ha s risen from24 % toove r40% .Sinc e 1960th enumbe r ofdair y cowspe rh a of grassland

122 has increased by 50%.Th e average stocking rate iscurrentl y 1.76 dairy cowpe rha .Th emil kproductio n perh ao f grasslandha s risenb y 88% in2 0year s and isapprochin g 10.000k gpe rha .

Polder areas inth eNetherland s

Thisbring sm e toth e subject ofm y talk.Polder s inrelatio nt o agriculture.Mr .Schult zha salread y shownyo ua ninterestin g table explaining the threedifferen t kinds ofpolder s tob e found inth e Netherlands.H e toldyo u thato f thetota l 3.4millio nh ao fDutc h land, 2millio nh a arepolde r land.Tha t ist osay ,lan dwhic h isenclose d by adyk ean dwher e thewate r level isartificiall y controlled.

Thegreate rpar t ofthi s land consists of low-lyingpea t land andth e oftenno t easily accessible clay land around thebi grivers .Th esecon d group consists of former lakes shichhav ebee ndrained ,an dwhic h account for 315.000ha . The third group ismad eu p of theempoldere d parts of the sea,totallin g 350.000ha .Th eagricultura l productionpotentia l of this land isclo ­ sely connectedwit h thewa y inwhic h the landwa s empoldered and brought intocultivation .

From thisrevie w iti sclea r that aver y largepar t ofDutc hagricul ­ tural land lies inpolders .Th ewa y inwhic h thepolde r originated,th e conditions ofwate r control,distributio n ofplots ,an d of courseth e typeo f soil arever y important determining factors for theproductio n potential foragriculture .I wil l explain this ingreate rdetail .

Thehistor y ofDutc h farmingha sbee n largelydominate d by the struggle againstwater ,th eformatio no fpolder s and thepossibilit y ofcontrol ­ ling thewate r level in thosepolders .Thi shistor y isreflecte d to thisda y inth e lifestor y ofman yDutc h farmers.Indeed ,I mysel f can tellsuc ha story .

Iwa sbor no na "terp" ,a dwellin gmound ,i nFriesland .Gre wu p ona farm inon eo f thene wpolders ,th eNorth-Eas t Polder,4. 5m belo w sealevel,wher em y fatherdecide d tostar t ane wfarm ,an d Ihav ei n

- 123- fact spent thegreate rpar t ofm y life ina polder . The "terpen"o f theNorther nNetherland s are artificial dwellingmounds, whichwer euse d asa refug efo r thepopulatio n intimes ,whe n storm tides flooded the country,befor e itwa sprotecte d bydykes .

Whatkin d of alif edi d our ancestors lead?The y lived inconstan t strugglewit h thesea ,whic hprovide d themwit h fishan ddeposite d fertile silt,bu t atth esam etim erepresente d anever-presen t threat as thesea-leve l rose.I f the seaencroache d upon the land,th eharves t was lost and the landwa s inundatedwit h saltwater .Regula r farming onlybecam epossibl e after seadyke sha dbee n constructed.

A seadyk eprotect s thelan d from thedange r fromflooding .Howeve r the fact that thebuildin g ofdyke s doesno tmea n that allth edanger shav e been conquered isprove db y thelon g listo fdyk ebreache s andfloods . Inee d onlyremin dyo uo fth enigh t of 1stFebruar y 1953,whe n the dykes inth e South-West of this countrywer ebreache d and thatpar to f the countrywa s inundatedb y theNort h sea.Thousand s ofpeopl e drowned, andman y cattlewer e lost.Hunderd s offarm swer e destroyed.Th elan d was coveredwit h saltwater .Year s afterwards,th eeffec t of thiso nth e structure of thesoi lremaine d noticeable insubstandar d cropyields . Thisdisastrou snigh tresulte d inth erigorou s decision torais eth e height ofal lou r seadyke s and shorten thelengt h ofou r coastline . (Thisamount s tolockin g thestabl edoo r after thehors e isstolen .A s amatte r of fact theDutc h saying ismuc hmor e appropiate inth econ ­ text.Literall y translated itruns : thewel l isonl y filled inafte r thecal fha s drowned).

Agriculture inth e "lowpolders "

Inth epast,th elow-lyin gpea t landwer e surroundedwit h lowdyke so r embankments inorde r toprotec t them against anexcessivel y highwate r level.Fo rman y centuries,th egroun dwate r inthes eextensiv e regions wasmaintaine d ata ver yhig h levelb ymean s ofwid e ditches,becaus e thepeopl ewer e afraid that alowe rwate r levelwoul d allow thepea t to dry out andbecom e awater-impermeabl e layer,whic hwoul d seriously reduce thefertilit y of those lands.Bu t such ahig h groundwate r level

124 hasman y disadvantages for thefarmer .Th e softness of thegroun d means thata lo to fgras s islos t throughbein g trampled by grazing cattle.Thi s loss isofte nmor e than50% .A Dutc h farmerwil l thensay , "mycow s grazewit h 5mouths" .I nth e spring,gras s growthbegin s late, and ina dr y summer itwil lquickl y dry outbecaus e of its shallowroo t system.Durin g the spring and autumn,th emor eremot epart s of thefar m areentirel y inaccessiblewithou t destroying the turf.Suc hplot s are used ona ver y extensive (asoppose d tointensive )basis ,ofte nmerel y asunmanure d grassland forhay . Inth eextensiv e areaswit h riverbasi s clay- betwee n thebi griver s- thesituatio nwa s scarcely anydifferent .Onl y inth epas t fewdecade s have theseregion s improved,agriculturall y speaking. Thanks tointensiv e research intobette rdrainage-methods ,bette r opening-up of inaccessible areas,an d thanks tolan d consolidationo r redistribution ofplots ,th eproductio n conditions ofextensiv eagricul ­ tural areas inth eNetherland swer e somodifie d thatmoder n farming becamepossibl e inthos eregion s aswell .

Effect onth epopulation' s character

The centuries-long struggle against thewater ,th eofte n great isolation and thehar d lifeha s left its traces inth ementa lmake-u p ofth e population inman ypart s of theNetherlands .Withou t going toodeepl y into thismatter ,I believ e that the independent charavter ofman y Duthmen,thei r longing for freedoman d independence,thei rhabi to f acting inaccordanc ewit h theirow n ideas,thei r courage intacklin g problems and theirperseverenc e inconquerin g adversity hasbee ncreate d tosom eexten tb y theconstan t struggle forexistance .Th epioneerin g spiritwhic h characterized theDutc hpeopl e inth epast ,no t only inth e sense ofdiscoverin g unknown continentsbu t also inth esens e ofturnin g unproductive areas ofpea t andmars h into fertile lando r draining inland lakes inou row ncountr yha sno tye tbee n extinguished. That spiritha s certainly notbee nextinguishe d among the farmers,wh o were thefirs t tomov e intoth e immeasurably largeexpans e of thene w land createdb yempolderin go f theIJsse lLake .

125- Following the theme ofthi s conference,i ti s important todra wyou r specific attention toth egrea t importance ofprope r agricultural grouping ofplot so f theempoldere d areas.Afte rbein greclaimed ,th e drained landmus tb ebrough t into cultivation.Thi s involves anumbe r ofproblems ,suc has : -wha twil l the landb euse d for (farming,forestry ,natur ereserve , urban area); -ho wdee pmus t thegroun dwate r levelb e (thatdepend s onth efutur e use); -ho w largemus t theplot s and fieldsbe ,ho w largemus t thene w agriculturalholding sbe ; -wil l the landb e sold,o r leased oroperate d by theStat e itself? Youwil l appreciate that the state inwhic h the land ishande d overan d thecondition s onwhic h the land ismad e available toth eprivat e farmerwil lb eo f theutmos t importance tohim . Ishoul d liket oexplai n that toyo u inbroa doutline .

Thedraine d lakes

TheBeemste r -th e first large lakedraine d inth eNetherland s -wa s empoldered between 1608an d 1612b y the legendaryLeeghwate rwit h the aid ofabou t 40windmills ,o nth e instructions ofDirc kva nOss ,th e Director of theEas t IndiaCompan y (Verenigde Oost-Indische Compagnie), thecarte l ofAnsterda mmerchant swh o financed theproject .The yprove d tohav eprogressiv e ideas,fo r theplo t distribution of theBeemste ra s itwa s arranged 350year s agoremain s suitable formoder n farmmanage ­ ment tothi sday .

Another example isth eHaarlemmermee r -whic hwa s drained in 1850 aft,eri n22 5year s 15plan sha dbee n submitted forit sdrainage ,al l ofwhic hwer ewrecke d foreithe r technical of financial reasons- which alsoha s afor mo fplo t distribution andwate r controlwhic h makes itexcellen t forpresent-da y farming.Th e fact that thispolde r iscurrentl y subject tosever e erosionb yhousing ,recreatio n andou r national airportmean s agrea t loss toagriculture .

As soon asthes e inland lakesha dbee ndrained ,th e landwa s soldt o

126 thehighes tbidder ."Rip ean d green"establishe d itselfher e ina single area.Professo rGroenma nwrot e about this systemo f freecoloni ­ sationa sfollows : "Although theare aappeare d richly greenfro mweeds ,ye t itwa s still far fromrip e tob e cultivatedwit h success".I twas ,i nfact ,a figh t toth edeat h againstnature ,i nwhic h the strongest,th ehealthies t and themos t fortunate couldwithstan d the struggle.Perhap s itwa s only thewealthies t Ultimately,thi s systemo f freecolonisation ,b y means of aproces s of strict selection,le d toa prosperou s society. Butnot e thewor d ultimately.'fo rwhil e thefirs t generationha d an extemely difficult,poo r andhar d life,th e second generationbenefite d from itan d thenex t generation evenenjoye d aver y decent standard of living,thank s toth eeffort so fth epioneers .

Thene w IJsselLak epolder s

When theIJsse lLak epolder swer e constructed acompletel y different policywa s followed.Th eGovernmen t itselfbor e therisk s ofbringin g thedraine d areas intocultivation ,b y operating themitsel f forth e first fewyears .Onl y after itha sbecom e clear that therear en o exceptional risks toth eprivat efarme ri noperatin g the landindividual ­ lyar e thefarm swhic hhav e alreadybee nbuil t inth ene wpolde rmad e available toprivat e enterprise.An d thismetho d hadprove d asuccess .

New landhelp s theol d

Inth e course of time,th epolic y relating toth econdition s onwhic h the land ismad e available tofarmer sha d undergone quite afe wchanges . The firstpolde rwa s theWieringermeer ,containin g 20.000h a ofland . Anybode could apply fora farm .Applicant swer e selected on thebasi s ofproficiency , financial soundness and good familyreputation .

Inth eNort hEas tPolde r -whic hwa s letou t inth eperio d from 1940t o 1962- certai n groupswer e givenpriorit y inth eallocatio n offarms . First came the group ofpioneers ,wh oha dhelpe d reclaim thepolder . Thencam e farmers fromWalcheren ,a nislan d in theSout hWes t ofth e Netherlands,whic hha d suffered flooding inth eWorl d War asa resul t

127 of thedyke sbein gbombed .Th e farms onWalchere n arever y small.B y offering these farmers ane w farmi n theNort hEas tPolder ,th efarm s onWalchere n canb eenlarged . Soth ene w land isutillize d forth epurpos e of improving farm structure inolde r regions.Thi smetho d ofmakin gnewl y reclaimed land serviceable forth e improvement of theproductio n conditiono nth eol d land,ha sbee nextende d toa nincreasin gdegree .

Inth eFlevopolder ,hal f of thefarm swer e allocated tofarmer s from land consolidation areas,tha t ist osa yarea swher e aplo tredistribu ­ tionprogramm e isbein g implemented.Thi srelease s land intha tare a enabling the farms tob emor eefficientl y parcelled. Forpastur e areas inparticular ,i ti smos t important that thelan d shouldb edirectl y adjacent toth e farmbuildings .Thi s allowsth e dairy cattle tob emilke d inth eparlou r during the summer aswell . If thefarm s onth eol d land are situated tooclos e together,th elan d ofa farme r on theol d land canb euse d toreparce l the surrounding farmsb yofferin ghi m afar mi nth ene wpolder .I nthi sway ,ever yh a ofne w landmake s itpossibl e for5 h a ofol d land tob e reparcelled.

Inaddition ,som eo f thene wholding s inth epolde r arereserve d for farmers forced toleav eth eol d landb y urban expancion orroa d construction.Particularl y ifth e farmerhold s the land onleas e inth e caseo fexpropriatio n thefarme rwil ln ob e able toobtai n ane w leasehold farmelsewhere .I nsuc hcases ,th ebes t solution ist omov e into thene wpolder .

Freehold or leasehold?

Apoliticall y important issue isth equestio n ofwhethe r thelan d shouldb emad e available toth e farmers ona freehol d (i.e.privat e property)basi s oro na shor t or long term (i.e.hereditary )lease . Although Parliament originallyvote d infavou r of allthre e formso f tenancy,i twa s decided inpractice ,unde r socialist pressure,t oretai n the land asStat ePropert y and let italmos t exclusively ona shor to r long lease.Thi sha dmad e theStat e into thebigges t agricultural landlord inth e country.I mus t add,no t always toth e full satisfaction

128 of the farming community.An d Parliamentary control over the State's behaviour as landlord hasprove d tob e extremely difficult,becaus e the StateLan dManagemen t ispar t of thebudge t ofth eMinistr yo f Finance.And ,o fcourse ,i nthi sparticula rbudge t theproblem s surrounding Government expenditure and financial economies aremor e important toth e financial experts inParliamen t than land leasepro ­ blems inth eIJsse lLak ePolders. '

Sizeo f thefarm s

Anotherpolitica l issue isth equestio no fwhethe r toallocat e large orsmal l farms?

Besides suchaspect s aseconomi cviabilit y and employment and social acceptability,th emai nobjectiv e thatapplie she r ist oprovid e solutions toproblem s affecting theol d land. The lesson tob e learnt from thepas t istha twha twa s considered tob e a reasonably largearabl e farm in 1930- 2 0t o2 5h a- i sno wto osmall . On thebasi s of thisexperience ,yo u should really start froma far m size sucha s toallo wa margi n toabsor b futuredevelopment s asye t unforeseen.Th edesir e topu t thene wpolde r tous e inorde r tosolv e problems onth eol d landmean s thatwhe n that farmermove s toth e IJsselLak epolder sh emus tb e ablet ocontinu e tofarm .An d thismean s that thefar m sizemus tb e sufficient tomak e sucha mov e toth epolde r bothmentall y and financiallypossible .

When afar m isaccepte d inth epolde r itgenerall y involvesa considerable financiel outlay.Th eol dfar mha s tob e sold toth eState , thenyo u takeove r thene w farm,eithe r ona shor t of long termlease . Inth ecas eo f ashor t lease,th e land comeswit h a"rum pbuilding" . The tenant farmerhimsel fha s toprovid e thehom e aswel l asth e equipment for theshed ,surfacin g theyard ,etc .I nth e caseo fa lon g term lease,th e farmeha s toprovid e allth ebuilding shimself .Th e costs involved are around 800.000 to 1millio n guilders inth ecas eo f a short lease,an d from 1-1,5 million guilders fora lon g lease farm.Thi s amount isonl y economic inth e caseo fholding swhic h are not smaller than4 0ha .

129- At thispoin t Iwoul d remind you that the average sizeo fDutc h agricultural holdings is 18ha .B y comparison,th e farms in theIJsse l Lakepolder s arerelativel y large,wit h anoptimu m location,al lth e land inon epiec e around thefarmhouse ,excellen twate r controlan d new farmbuildings .

Theus e ofmoder nholdings ,wit h farmerswh o areonl y allocated a farm ifthe y satisfy anumbe r of conditions,fo rexampl e agricultural efficience,hav e asignifican t positive influence on the farmers working theol d land. Thepolde r thereforeha s acertai nexemplar y effect.Ne wmachine s and methods ofcultivatio n areofte n tried out inth epolde r first.Th e relatively favourablebusines s results enhance thewillingnes s among farmers onth eol d land tomak e investments and introduce improvements, paricularly asregard s reparcelling andwate rcontrol .

Theresul t istha t the importance ofgoo dparcellin g andwate rmanage ­ ment isbrough t toth eattentio no fman ymor e farmers.Lan d consolida­ tionha sbecom e aver y importantpolic y instrument inth eeffort st o improve thestructur e ofagricultura l andhorticultura l holdings.Thi s ismad eeviden tb y thefac t thata tth epresen t timeapproximatel y40 % ofou r cultivated land iseithe rundergoin g orabou t tounderg o alan d consolidationproject ,an d that 35%o fou r landha s alreadybee n reparcelled. TheStat e iscurrentl y investing 5.000guilder s perh ai n land consolidation.Par t of thismone y- averagin g about 50%- ha st o be repaidb y thefarme ro rhorticulturis t after completion.Eac hyear , about 40.000h ao f land arereparcelle d andreparcellin g starts ona further 40.000. Theentir e land consolidationprocedur e from thebeginnin g toth een d takes from2 5t o 30years .Admittedly , iti sno tpossibl e toachiev e the same ideal land distribution as inth ene w IJsselLak epolders .Th e ultimate effect dependsver ymuc h onth equestio n ofwhethe r therei s sufficient room toallocat e every farmer themaximu m amount oflan d immediately adjacent to his farm.Th epossibilit y ofmovin g anumbe r of farms toth epolde rmean s that thechanc eo f successbecome s considerablybetter .T opu t itbriefl y thene w capacity of agricultural land inth eIJsse lLak epolder sha s afa r larger indirect effect onth e

130 old land than isofte n realised. Ihop e that Ihav e succeeded in givingyo u some ideao fho w important iti s toDutc h agriculture asa whole toreceiv ene w farmlandwit hmoder n and efficientfarms .

Changing socialview s

Over theyears ,ther e isanothe r factorwhic h influences theorganiza ­ tiono fou rne wpolders .Tha t factor is thechangin gview swithi n society as toth evalu e ofnature ,th ecountrysid e and theenvironment . Thisha smad e itself felt inth edistributio n of landutilizatio n in thene wpolders . Inth eWieringermee ran d theNort hEas tPolder ,practicall y allth e available landwhic hwa sno t required forbuildin ghouses ,i sbein g used foragricultura l purposes.I nEaster nFlevolan d 75%i sagricultura l land and inth enewes tpolder ,Sout hFlevoland ,n omor e thanhal fo f the land isbein g assigned anagricultura l function.I n these twoareas , besides thespac e allocated forhousing ,th earea sdesignate d asnatur e reserves and forest areas are 11%an d 18%respectively . Inothe rwords , aver y significant increase.

TheMarkerwaar d

This change inth eappreciatio n ofnatur e and countryside alsofind s expression inth ediscussio n concerning theMarkerwaard ,th elas to f the IJsselLak epolders .I si tgoin g tob e constructed ornot ?Debat e onthi s subjectha sbee n continuing forth epas t 10year s inpolitica l circles inTh eHague .Man y studieshav ebee n carried outb y supporters and opponents.Actio n groupshav ebee n formed.I nth eend ,th e Government decided tobuil d a40.00 0h apolde r surrounded bywid e lakes covering 20.000ha .But ,firs t of all thispla nha d tob epresente d to thepubli c fordebate .Th eopponent s -heade db y thenatur econser ­ vation organizations -wh ofrequentl yfin d iteas yt omak e thenews ­ papers and television,stat e their argumentwit hpersuasiv e simplicity: intervention inth eenvironmen t isa crime .A n openinlan d lakeo fthi s size suddenlybecam e represented assomethin gunique ,uniqu efo r recreation anduniqu e forwate rbirds . Itshoul db eno tb e sacrificed merely for thepurpos e ofmakin geve n

131 more agriculturalproducts ,whic h arealread y inhug e surplus.Thi s fishermen,seein g their livelihood endangered,joine d inth ecampaign . Public opinionwa s aroused.Certai nmajo rpolitica lpartie svoice d their objections toth ene wpolder ,other swer eno t sosure .An dye t -I consideruncertaint y tob e absolutely irrelevant tothi smatter .Th e main objectionswhic hhav ebee nraise d against theMarkerwaar d prove upon analysis tob euntenable .I bas em y opinion ona repor tproduce d by seniorofficial s responsible fordealin gwit h thismatte rwithi nth e threeministrie s concerned:Are aplanning ,Traffi c andWaterway san d Finance. Themai n objectionswhic h theopponent shav e raisedare : - losso fjob s inth efishin g industry; - losso funspoile d openwate r asa natur ereserve ; - risko feve nmor e over-production ofagricultura lproducts ; - losso funiqu erecreatio n facilities for largeyachts .

Letm e consider these arguments oneb yone .

1 The fishing Industry

If theMarkerwaar d becomes apolder ,th efishin g industrywil l lose 40.000h ao f fishingwaters .I twil l retaina remainin g 160.000h ao f openwate r inth eIJsse lLak eregion .Th e loss toth efishin g industry ancillary andmanufacturin g firms,i sestimate d by espertsa t2 6 million guilders interm s ofadde dvalu epe r annum.I fonl yhal f ofth e Markerwaard ismad e intoagricultura l land,tha t agriculture,includin g ancillary andmanufacturin g industry,woul d yield anadde dvalu eo f 150millio n guilders.Tha t isn o less than 6time s asmuc h asth elos s tofishing . Interm so fjob sa swell ,th e loss toth e fishing industry ismor e thancompensate d by theadditiona l jobscreate db y agriculture inthi spolder .

2 Thevalu e of theMarkerwaar d asa nope nnatur e reserve

The losso f the largeMarke rLake ,a large-scal enatur e reserve,wil l admittedlyb ever y real if thepolde r comes about,bu t that lossi s offsetb y certain gains.Le tm ementio nhus t threematters :

132 1)i twil l create aconsiderabl y longer coastline,tha tmean s considerablymor e food forcoasta lbirds ; 2)a ne wnatur e reserve isplanne d opposite theOostvaarde rLakes .I believe that thispossibilit y alone outweighs the losso fpar to f theope nwater . 3)th e important indirect effectswhic h areofte n ignored.Empolderin g means that after theyea r 2000 therewil lb emor e space forurba n construction inth evicinit y ofAmsterdam . Itmean s lessris ktha t thegree nhear t ofHolland ,th eextensiv epastur e areas inth e centralpar t of this country,wil lhav e tob euse d forbuildin g houses,a t thebeginnin g of thenex t century. Iwoul d have thought that thisfacto r isno tunimportan t fromth e viewpoint ofnatur econservation .A sevond positive effect fornatur e conservation istha tdesignate d nature reserveswhic h atth epresen t timear estil lbein guse db y farmerswil lb e ablet ob epurchase d more rapidly and cheaplyb y theStat e if the farmer isoffere d a holding inth epolder .Tha tmeans :les sris ko f losing thenatura l assetswhic h arealread y there.I nbrie f theMarkerwaar d alsooffer s a loto fadvantage s fornatur e conservation aswell .

3 Recreational aspects

The argument that theMarkerwaar d shouldno tb ebuil tbecaus e itwil l result inlos so frecreationa l space for largeyacht s or seagoing pleasureboat s isa rathe r elitist argument.O f the200.00 0h ao pope n water, 160.000wil l remain.Th eresultan twid eperiphera l lakewil l offer recreational facilities for far largernumber s of lesswealth y recreation seekers.Smal lboats ,win d surfers and that allclos e toth e Randstad, theWester n conurbation.Wha t ismore ,th eextende d coastline will offermor e recreationfacilities .

4 Agricultural surpluses ofproduktio n

Iwil ldisregar d thequestio n ofwhether ,i nvie w of therat e ofth e population growth and structural decrease inth eare ao f cultivated land,w e shouldno t expect astructura l food shortagewithi n theEE Cb y theyea r 2000.Th eare ao f agricultural land inth eMarkerwaar d polder

- 133 would represent 0,04%o f the totalare ao fagricultura l land inth e EEC. Inth eperio d up to 2000 inth eNetherland s alone iti sexpecte d that 400.000ha ,i.e . tentime s theare ao f theMarkerwaard ,i sgoin g tob e lost foragricultura l purposes inth e formo fhousin g ornatur e reserves.Surel y thisdisprove s thecredibilit y of talking about the Markerwaard polder resulting inbigge r foodsurpluses .

No:w emus thav e theMarkerwaard . Thecost s ofconstructio n and developing itfo rcultivatio nhav ebee n estimated at 1.650millio n guilders.Temporar y utilization and lease revenues over thefirs t 20year s following its drainage canpotentiall y earn65 0millio n guilders.Therefor e thene t costs ofth edraine d polder willb e 1millio n guilders (spread over 20years) .

What doyo u get for this: 1)40.00 0h ao f first class agricultural land.Tha twork s outa t 25.000guilder s perha .I f theStat ewante d tosel l this landi t could do soa ta profit . 2)Spac e forbuildin ghouse s andundertakin g other socio-economic activities at thever y centreo fth e country.T obuil dhouse sth e Statewil lno t firsthav e toexpropriat e andprepai r goodagricul ­ tural land elsewhere forhous ebuilding .

Ihav e alreadymentione d thebenefit s interm s ofrecreatio nan d nature conservation.

For farming,th epolde rwil loffer : 20t o30.00 0h a of space for ideallyparcelled ,ultra-moder n agricultural andhorticultura l holdings.Par t of thepolde rwil lb e particularly suitable forgrowin gbulbs .

Thismeans ,directly :- extr ajob s (forabou t 1.500 persons) - extraadde dvalu e (about 125- 150millio n guilders/year) indirectly: theeffec t on theol d landwil lb e evenmor e substantial.

134 Ihav e already explained howth epolde r landca nb euse d inorde rt o improveth eparcellin go fth eol dland ,b ymakin g itpossibl e tooffe r farmers from land consolidation areasa ne wfar mi nth epolder .Thi s means that theMarkerwaar dwil l enablebetwee n6.00 0an d8.00 0ol d farmshav ea bette rparcellatio nwhic hwil lyiel d acos t savingo f 500guilder spe rannu mfo rever yhectare .

Inshort : TheMarkerwaar dwil lpa yfo ritsel f sot ospeak .I a mconvince d that this investmentwil lbea r fullfruit .Th ene wGovernmen twil lhav et o make achoice .Th ene wpolder ,ne wjobs ,ne wspace ,ne weconomi c potential,o ri tca ndispla y theunenterprisin g spiritwhic hi ss o oftenth echaracteristi c ofpoliticians .

I challengeth eGovernmen t andParliamen t totak ea positiv edecision . Admittedlyw ear eshor to fmoney ,bu tw eca neasil y affordth e Markerwaard. Inth eEas t Schelde,w ear espendin g an6 milliar d guilders inorde rt oconstruc t anope nstormsurg ebarrie r instead ofa close d dam,merel y forenvironmenta lreasons . TheMarkerwaar d will cost lesstha n20 %o ftha t amount,sprea d overa period of15-2 0years .W ehav e theknowledg e andth eexperience . Theprojec t cannot failt ohav emajo rpositiv e effectso nemployment , spacefo rurba n construction,agricultur e andrecreation .

Ihav emad ea nattemp t togiv eyo usom e ideao fth eway s inwhich ,i n thepas tan di nth epresent ,ne wpolder sar edevelope d foragriculture . And thatho wth ene wlan di shande d overth efirs t agricultural pioneersan dth ene wlan d iss ovitall y important. Butals oho wi tca nmak e acontributio n toimprovin g thestructur eo f theol dland .Ho wth emoder nholding s inth ene wpolder s generatea tremendous spin-off effecto nth eentir enationa l developmentsi n agriculture inth efor mo fne wmachine s andmethod so fcultivation . Howa polde r canals omak e asocia l contributionb yprovidin g extra opportunities foragriculture ,housing ,landscap e andrecreation .

I hope thatI hav e succeeded inmakin g ausefu l contribution toa ninte ­ resting discussiono nthi ssubject .

135 136 AGRICULTUREAN DFOO DPRODUCTIO N INPOLDE RAREA S A oase studyfro mBanglades h H.Bramme r FAOAgricultura lDevelopmen tAdvise r Dacca,Banglades h

Abstract

Bangladeshillustrate spolde rdevelopmen t issuesi na densely settled, subtropical,deltai cenvironment .Si xfloodplai ntype s- active ;me ­ ander;estuarine ;tidal ;piedmont ;pea t basin- provide different opportunities,need san dproblems .A I964Maste rPla npropose d 35 embankment/polder projects covering 5»8millio nha .To-date ,abou t0* 5 millionh ahav ebee nfloo dprotecte dan d85,00 0h a irrigated, increasing annualric e productionb yabou t 1millio n tons (net).Slo w implementa­ tioni sdu et oai ddonors 'recognitio no f technical difficultiesi n constructingembankment san dheadwork so n the unstableGanges-Brahmaputr a riversan do falternative , quicker,developmen t modes,especiall y small- scale irrigation.Problem s of seepage/waterlogging anduneconomi c returnsresultin gfro m farmers' slowadoptio n of planned cropping patternsar e partlydu et o planners'insensitivit yt obot hsoil-cro p relationshipsan dfarmers 'cro pproductio n capacities.Firs t generation problemsals o include:lo wirrigatio n coverage duet o seepagelosses ; erosiono f embankments;optimu m economic designswhic hleav e depression sitesundrained ;an dlac ko fwater managemen t intida lbasins » Second generationproblem sinclude :siltatio n of tidal creeksoutsid epolders ; waterlogging incana lirrigate dareas ;zin can dsulphu rdeficiencies ; spread of settlement ontoflood-protecte dland ;an dbreachin go f coastal embankments by shrimp producers.Agro-economi c surveysan dlan dus e regulationsar e recommended.

137- Introduction

The organizers of the Symposium on Polders of the World original ly requested a paper giving an overview of agricultural aspects of polder development outside the Netherlands* That task proved to he impossible within the time and resources available to the author in Sangladeah * However, it is expected that the Symposium itself will provide such an overview through the combined contributions made by delegates coming from many individual countries» The author has chosen to speak instead on polder development in Bangladesh. The objective of this is not to provide a detailed descrip­ tion of polder development in Bangladesh but, rather, to use Bangladesh examples as a means to illustrate principles, experience and issues of wider relevance. It must be emphasized that the views expressed are those of the author alone, and do not necessarily reflect the views either of his employer, FAO, or of the Government of Bangladesh which he serves.

Environment and demography

Bangladesh has both the physical and the demographic environments where polders are most needed. Alluvial floodplains which are seasonally or p tidally flooded occupy 80 percent of its total land area of 143,000 km . Almost the whole of the country's population of over 90 million is crowded onto those floodplains, with densities ranging from less than 500/km in two coastal districts to over 1,000/km in Comilla, the most densely settled rural district. For the whole country, the density now is over 628/km . Considering the fact that more than 80 percent of the population is rural and dependent on agriculture, that is a very high population density indeed. It can be regarded as all the more so when seasonal flooding is taken into account. More than half of Bangladesh goes under water for part of the year. Within the floodplain area, it is estimated from soil surveys that only about 8 percent of the agricultural land lies above normal flood-level. About 17 percent normally is flooded up to 30 cm deep, about 40 peroent is flooded 30-90 cm deep, almost 20 percent 90~180 om deep and about 15 percent deeper than 180 cm. Some land in the north­ east is submerged deeper than 5 m. Flooding normally lasts for 3—3

- 138 - months, depending on topographical position. Host land becomes dry during the dry Beason, but some depression oentres stay wet for part or all of the dry season. The subtropical monsoon climate allows crops to be grown throughout the year. Annual rainfall ranges from 1,250 mm in the extreme west to more than 5i000 mmi n the north-east, concentrated in a summer rainy season lasting 4-7 months. The dry season is divided into a cool winter, during which temperate crops such as wheat and potato can be grow, and a hot, pre-raonsoon season during which erratic, high-intensity, thunder showers occur* Coastal districts are periodically ravaged by cyclones (a hurricanes, typhoons) and accompanying storm surges.

Physiography and soils Host of the country comprises the combined delta of the Ganges, Brahma­ putra and Heghna rivers. This area can be divided into six broad physiographic types (Hap). a) Active and very young floodplains along the major river channels (700,000 ha) which are subject to bank erosion or deposition of new sandy or silty alluvium each flood season« Such unstable land is not suitable for embankment projects* b) Young and old meander floodplains of the major rivers (5*7 million ha) whioh are characterized by a ridge and basin topography with 2-5 m local difference in relief. Predominant soils are heavy silts to clays with developed profiles 30-120 cm deep over a stratified substratum. Such land is suitable for polder projects, so long as embankments are set well back from active river channels and there axe suitable sites for irrigation/drainage headworks on stable tributary channels. The Ganges-Kobadak (G-K) projeot, referred to later, is on the Ganges meander floodplain. c) Young and old estuarine floodplains (3*1 million ha), mainly east of the Heghna river, which are characterized by almost level relief (<2m), few or no natural channels, and deep silty deposits in whioh soil profiles 20-120 cm deep have developed. Such land is suitable for polder projects, provided that embankments and irrigation/ drainage headworks can be sited away from active river channels« The Chandpur and Dacca-Narayanganj-Derara (END) projects, referred to later, occupy parts of the old and young Heghna estuarine floodplains.

139 BANGLADESH PHYSIOGRAPHY OF FLOODPLAINS

LEGEND I I J Acfivo rivtr floodploin

| 2 |M«ondtr floodploin j 3 lEituorint floodploin

| 4o {Tidal floodploin - ncn-sollnt •- International boundory

I 4» iTidol floodploin—lolinf — Unit boundary

I 4c JTidol floodploin— mono/ovo — Wldo rlv«r

| 5 |»lluvlol fon —• Narrow rlvor

I 6 [Pool booin • OACCA

I 7 |Mi lI » ond ttrroct»

DEMHTMENT OF SOIL SURVEY

140 d) Tidal floodplains occur mainly in the south-west, locally in the south-east. They are characterized by almost level, saucer-shaped, basins with <1 m local difference in elevation, and numerous tidal creeks» Clay soils predominate. About 400,000 ha is non-saline) about 600,000 ha is saline, (most of it only in the dry season). The Coast­ al Embankment projeot oocupies most of the saline tidal floodplain land, and the Barisal Irrigation Project (which includes embankments) occupies a part of the non-saline Ganges tidal floodplain. e) Alluvial fans and piedmont plains (1.1 million ha) occurring partly in the north-west near the foot of tbs Himalayas, the rest mainly adjoining the eastern and northern hills. Relief often is irregular, and soils vary from sands to clays. The embankment of hill-foot rivers provides difficult problems because of the deposition of sediments within embankments following flash floods and the constant risk of embankments being breached. The Kanu, Huhuri and Karnafuli projects oocupy hill-foot sites. f) Peats (200,000 ha) occur most extensively in the transition zone between the Ganges meander and tidal floodplains in the south-west. The empolderment of peat basins is suitable so long as they are not deeply drained, which would allow the peat to shrink and oxidize. The land should be kept permanently wet or moist. On all floodplains, there is a characteristic pattern of permeable, usually loamy, soils on the highest parts and impermeable, usually clay, soils on the lower parts. The proportions between light and heavy soils differ both between major floodplains and within them. Gener­ ally, heavy soils occupy most of the landscape. Rapidly permeable soils occur mainly on high floodplain ridges, some piedmont fans (especially that in the north-west), and some temporary islands on active flood- plains. The most extensive soils are Fluvaquentic Haplaouepts (Eutric and Calcaric Fluvisols in the FAO/Unesco system). Ganges river alluvium contains lime; so does young Meghna estuarine alluvium, although only in small amounts. Ganges tidal, Brahmaputra river and old Meghna estuarine alluvia are neutral to moderately alkaline in reaction, but not calcareous. Alluvial fans and Meghna river deposits are usually slightly to moderately acid.

141 - Because ofth e seasonal cycleo f flooding anddryin gout , soil develop­ mentusuall y israpid .Th e seasonal changescaus erapi ddevelopmen t of structure (where texturesar e suitable)an dth e developmento f iron oxidationmottleB *Alluvia l stratification isquickl ybroke nu pb y biologicalactivit y downt oth e permanently saturatedzone *Biologica l activity (roots,soi lfauna )als o increases subsoilporosity ,aeration , permeability andmoistur e holding capacity*O n theothe rhand ,cultiva ­ tiontend s todestro y topsoilstructur e andt o createa slowly permeable ploughpan,especiall y insoil s deliberately puddledfo r transplanting rice.

Soilfertilit y

The seasonalreductio nan doxidatio n of thetopsoi l- whichusuall y is cultivated, andofte n puddled- quickly decalcifieso racidifie sthi s layer,excep t in loamy soilswher e biologicalactivit y constantlybring s subsoilmateria lt oth e surfaoean dwher e the depositiono fne walluviu m neutralizes suchchemica l changes*However ,whethe r topsoilsar eaci do r alkaline inth edr y season,the y become neutral inreaotio nwhe n sub­ mergedan dreduced . Therapi dleachin go fmos t floodplain topsoilsconfirm sfiel dobserva ­ tionstha t most river andestuarin efloodplain sar eno t floodedb y riverwater .The yar sfloode dwit hrainwate r or the raised groundwater tablederive dfro mth e heavymonsoo n rainfallwhic h isponde do nth e landb y highmonsoo n seasonrive r levels* Siltyfloodwate r mainly depo­ sitsne walluviu mo nactiv e floodplainsan dth e immediately adjoining land, onunembanke dtida lfloodplains ,an do nalluvia lfan s (piedmont plains)a t the footo fhills . Thisha s important implications forembankmen t projects*Farmer s(and layofficials )believ e that thefertilit yo ffloodplai n soils ismain ­ tainedb ya nannua l deposit ofalluviu mfro mth e seasonal floods.Sinc e most floodplain areas dono t receive suchannua l deposits,an dye t clearly area t leasta sproductiv ea s thosetha t do- e.g., largearea s of theBrahmaputr aan dGange sfloodplain sar e triple cropped,withou t irrigationan dwit hlittl e orn o use offertilizer s- the self-evident fertility ofthes e soilsmus t bederive dfro m someothe r source.

142- Theread yavailabilit yo f phosphorusan dpotas hca nb eaccounte dfo r byth e seasonal cycleo freductio nan doxidatio n inthes e mineral-rich soils«However ,thi sphenomeno n cannot providenitrogen , andman y cultivated soils contain little organic matter asa nitroge n source*I t nowappear s certain that thenitroge n fertility ofBangladesh' sflood - plain soils isprovide db y biologicalactivit y inth efloodwate r itself, especially that ofblue-gree nalgae * It isprobabl e that suchorganism s canprovid eu pt o 30kg/hao fNitroge n annually,perhaps eve n moreo n deeply flooded landwher e deepwater aman isgrown .Sinc e these organisms are dependent on light for photosynthesis, it isprobabl e that they produce moreNitroge n inclea rwate rtha n insilt yfloodwater .There ­ fore,th e construction ofembankment s willno t outof ffarmers fro m these souroeso fplan tnutrition ,a t least onlan dwher ewetlan dric e continuest o begrown . That shouldno t betake nt o implytha tBangladesh' sfloodplai n soilsd o notnee do rrespon dt ofertilizers « Without fertilizerso r manure,th e natural fertilitymaintain sproductio n at onlya lowo r moderate equi­ librium level,fo r increasedyields ,particularl y forHYV san dirrigate d crops, it isnecessar y toad dN andP fertilizersregularly ,an dsome ­ timespotas hfertilizer salso .A swil lb e describedlater ,ther e is also increasingevidenc eo f zincan d sulphur deficiency insom eplaces .

Cropping patterns

Undernatura l conditions- i.e.,withou tartificia ldrainag e orirri ­ gation- farmers'croppin gpattern so nfloodplai n landar e determined largely byth e depthan d durationo f seasonalflooding , andth e length ofth e rainy season.Soi lpermeability , soilmoistur e holding capacity andth e presenceo rabsenc e of salinity areals o important, particularly for dry season cropsgrow nwit ho r without irrigation.Becaus e of the characteristicfloodplai n relief ofridge san dbasins ,variation s in soils,dept ho ffloodin gan dfloo dduratio noccu ro na local scale, even within the areao fa village.Croppin gpattern softe nar e complex, therefore.

143 Rice occupies about 10 million ba, which ie about 80 percent of titie cropped area. It can be grown in three seasons: - aus, sown in the pre-monsoon season and harvested in the monsoon season; - aßafi (which is photo-period sensitive), sown before or in the monsoon season and harvested at the beginning of the dry season; and - boro. sown in the first half of the dry season and harvested just before or early in the monsoon season. Aus and SB8& are mainly grown without irrigation, although irrigation is expanding in both seasons, either to increase security or to allow both crops to be grown in western areas where the 4-month rainy season is insufficient to support more than one rainfed crop. Boro traditionally was grown in depressions which stay wet for most or all of the dry season, but it is now grown widely with irrigation on relatively nicher land. Within the three broad rice groups, farmers have selected many thousands of rice varieties to suit their specific micro-environmental conditions, especially for the aman crop* Aman includes varieties with different maturity periods, tolerant of different degrees of salinity, zinc deficiency and iron toxicity, and adapted to different depths and duration of seasonal flooding. Some deepwater aman varieties can elongate their stems to as much as 4-5 metres* High yielding varieties (ffiCVs) of rice which have been introduced in the last 15 years are not adapted to a wide range of Bangladesh environ­ ments. In order to give high yields, they require good water control to provide a very shallow water depth, and relatively high fertilizer doses. The farmer will only invest in the latter where he feels there is sufficient security to ensure a reliable return on his investment* For that reason, the HYVs have spread to only an estimated 15 percent of the total rioe area. About half of this is boro. grown with irrigation in the dry season. The rest is about equally divided between aus and aman, grown both with and without irrigation on relatively heavy soils on land where the risk of damaging floods is low* It is in this context that polders are important for agricultural development in Bangladesh* About 75 percent of the floodplain land - about 8*5 million ha gross - is too deeply flooded for existing HTVs

144 - of rice to be grom in the monsoon season* Also, some of that land cannot be used for Irrigated HYV boro in the dry season, either because floodwater recedes too slowly or because the risk of early, pre-monsoon floods is too high. A further area of shallowfy flooded tidal land near the coast has soils or water which are too saline in the dry season for boro rice to be grown.

Master Plan

TheMaste rPla nfo rwate rdevelopmen t drawnu pb yth epresen t BangladeshWate rDevelopmen tBoar di n196 4envisage dpolde rdevelopmen t extendingeventuall y overa gros sare ao f5 »8 millio nha *Thre ekind s ofprojec t wereenvisaged :floo dembankment swit hgravit ydrainag ei n meanderfloodplai nan dpiedmon tplai nareas ;floo dembankment s with tidalsluic e drainage;an dfloo dembankment swit hpum pdrainage .Fo r mosto fth eschemes ,provisio no firrigatio nwa sals o envisaged, sometimesa sa secon dstage .Priorit ywa sgive nt ofloo dprotection . Eighteenyear slater ,onl y seveno fth e3 5majo rfloo dprotectio nan d irrigationproject senvisage di nth eMaste rPla nhav ebee nwholl yo r mainly completed.Fo ra variet yo freason si ti sdifficul tt oquantif y thebenefit swhic hthe yhav eprovided . Onemajo rreaso nfo rtha tderive sfro mth emeanin go fth ewor d 'completed'.Projec tauthoritie sten dt ous eth eter mt oindicat etha t constructionwork shav ebee ncompleted *Tha tdoe sno tnecessaril ymea n that project benefitshav ebee nbrough tt oal lth eprojec t commandarea » A particular problemarise si ntb a caseo fth e'completed 'Coasta l Embankment project,whic hsupposedl y protects1.0 8millio nh afro m saline tidalflooding «Man y sectionso fembankment shav ebee nerode d orbreached ,an dman y sluiceseithe rwer eno tinstalle do rhav e sub­ sequentlybee ndamaged ,s otha tman ypolder sar eno wpolder sonl yi n name.I ti sprobabl e thatonl yabou tone-thir d(o rpossibl y less)o f the 'completed'projec tare ais ,i nfact ,receivin gth eful lprojec t benefitso fprotectio nfro m salinefloodwater . A furtherproble mi sprovide db yth elac ko freliabl e cropproductio n statistics.Eve n where projectauthoritie smak eestimate so fcro p acreagean dproductio nwithi nprojec t commandareas ,i ti sdifficul t toestimat eth ene tincreas ei nproductio nattributabl et oth eproject ,

-14 5 especially in the case of relatively older projects, such as the G-K project. That is because, for most project areas, it cannot be assumed that, without the project, land use would have remained in the pre- project condition. In the case of the G-K project, for example, where transplanted improved aus and aman varieties have replaced the former broadcast, traditional aus and jyijan, varieties (and some jute), the comparison should be made with areas of similar land adjoining the project. Undoubtedly, there have been significant changes in land use outside the project area during the years sinoe the projeot started: in addition to the traditional aus and pfflan still grown in the monsoon season, there has been a considerable expansion of wheat, tobacco, cot­ ton and sugarcane production, part of it with small-scale irrigation. Because of the difference in crops grown, a realistic comparison could be made only on the basis of economic returns per hectare. Unfortunately, reliable data are not available for this purpose. Moreover, analysis would be complicated by the different levels of input subsidies provided within and outside the project area« On the basis of existing information, the author's best guess is that flood protection may actually have been provided to about half a million ha and irrigation to about 85,000 ha* The direct benefits in terms of increased foodgrain production may be about 1 million tons annually (net). In addition, because of the greater security which flood protection provides, farmers have been able to provide or obtain small—scale irrigation from surface water or groundwater sources, as well as to grow additional or better dry-season crops without irriga­ tion in some areas. Unfortunately, reliable data are not available to enable such benefits to be quantified.

Plan defects

Important though the direct benefits have been, they have been much less than was envisaged when the Haster Plan was prepared. It is instructive to examine the reasons why polder development has been so slow. There are lessons in this not only for Bangladesh but probably also for other countries. The first reason undoubtedly is because the Master Plan and its component projects were too narrow in concept and focus. The Master

146 Plan is primarily an engineering plan* It is not an agricultural development plan. With the benefit of hindsight, one can understand why that should be so. The origins of the Water Development Board and the Master Plan lie in the serious floods which ravaged what is now Bangla­ desh in the 1950's. Flood protection was then seen as a priority for providing security to crop production. Irrigation usually was a secondary consideration* Alternative possibilities for agricultural development were not considered at all. The engineering projects in the Master Plan were considered to provide a panacea for the country's agricultural development. Three main factors have combined to delay the implementation of that Plan. The major cause has been the reluctance of international donors to finance some of the major proposed projeots because of the technical difficulty of siting headworks on such major rivers as the Ganges and

Brahmaputrat whose banks can erode or recede by as much as 600 metres in a single year, and where intake or outlet canals can silt up in a single flood season. On the G-K project, for example, it takes six dredgers up to three months to desilt the 1,000 mintak e canal to the main pumphouse before irrigation can begin each year; and on the Chandpur project, 20 km of river embankments had to be rebuilt before the project had even been completed, because of actual or threatened breaches in the original embankment. Reservations were expressed, also, on the advisability of double embanking rivers as big and active as the Brahmaputra and Ganges. The lack of international agreements on water use in rivers originating outside the country was a further constraint on obtaining funds for projects involving irrigation as well as embankment. A second factor - and one also influencing donor funding - was the growing recognition during the seoond half of the 1960s that there were alternative - and cheaper - ways to increase crop production than through costly embankment and canal irrigation projeots. By 1970, about 24,000 small low-lift pumps and 1,000 tubewells had been installed, irrigating an estimated 370,000 ha. By 1981-Ô2, that number had grown to about 41,000 low-lift pumps, 12,000 deep tube-wells and over 50,000 shallow tube-wells, as well as more than 200,000 hand pumps, together irrigating an estimated 1.27 million ha. That figure compares with

147 - onlyabou t 05,000h airrigate dwithi nmajo rirrigatio nprojeot si n 1981-62.Althoug hth e limito feasil yavailabl e surface waterusabl eb y smallpump sha salmos t beenreached ,ther e remainsconsiderabl e scope toexpan dirrigatio nfro mgroundwater .Th e development of small-scale irrigationha sgreatl yexpande d cropproductio n inth edr y season,thu s reducing theurgenc yfo rfloo dprotectio n anddrainag e inman yseasonal ­ lyfloode dareas * Theemphasi s incro pproductio nha sbee n switchedt o therelativel y safedr yseason . Â thirddelayin gfacto rha sbee nth edifficult yan dexpens e ofacquirin g landfo rth e constructiono fembankment san dirrigation/drainag e canals.I na countrywher e theaverag efar mholdin gi sonl y 1*4n aan d 2 whereth eaverag e populationdensit y ismor etha n60 0pe rk m - and exoeeds 1,000/km insom e floodplainarea s- thereluctanc eo ffarmer s togiv eu pthei rland ,an dt o selli t onlya ta hig hprice ,i sunder ­ standable.Thi sfacto rals oha sinfluence ddonors 'decisions ,an di t hasle dt ochange ddesign swhic hminimiz e theamoun to f landneede dfo r irrigation distributionsystems .Preferenc eno wi sgive nt oth eus eo f many smallpump salon gexistin go r improvedinterna l channelsrathe r thant oth e constructiono fnew ,gravity-flow ,channels .

Farmers' alternatives

During theeightee nyear stha thav e intervened sinceth eMaste rPla n wasprepared ,ther eha sbee na slowlygrowin grecognitio n thattechnica l andphysica lfactor sar eno t theonl y considerations tob etake nint o account inagricultura l development.I nth eMaste rPlan ,i twa snaivel y assumedtha t landwhic hremaine duncultivate di nth e dry seasondi ds o because itwa sto odry ;som eplanner san dpolic ymaker s stillexpres s suchviews .Planner sals onaivel yassume dthat ,wit hth e provisiono f flood protectionan dirrigation ,farmer swoul d quicklyadop t improved methodso f cultivationan dgro wtw oo rthre ehig hyieldin g cropsa year.Projec tplanner s- andassertiv e aiddonor s- calculatedbenefit : costratio saccordingly ,showin gattractiv e rateso f returno npropose d investments. Twothing shav ehappene dt oupse t thoseearl yassumptions .On e istha t thereha sbee na considerable increase indoubl ecroppin gan dtripl e croppingo f land,eve nwithou t floodprotection ,drainag eo rirrigation .

148- The second isthat ,i nirrigatio nan ddrainag e project areas,farmer s baveeithe rno tadopte dth e croppingpattern sdesigne dfo rthe mb yth e project planners,o rthe yhav edon e somor e slowly than was projected. Inth e first case,soi lsurveyor shav e confirmedwha tfarmer sobviousl y knewalready :namely ,tha tman yfloodplai nsoil sstor e sufficient moisture after theflood san drain y seasont o supporta satisfactory cropo fwheat ,pulse so roilseed swithou t irrigationdurin gth e cool wintermonths .Th e changesfro m single todoubl e cropping,an dfro m doublet otripl e oropping,hav eresulte dmor efro mpopulatio n— and hence economic- pressure thanfro m the provisiono fmoder n technology. Muchlan d stillremain sfallo w inth e dry seasono r inth eau sseaso n inarea swit hrelativel y lowpopulatio ndensity ,eve nthoug h conditions mayb e suitablefo rgrowin gcrop sdurin gthos eperiods .Bi g farmers using share-croppersca nobtai na sufficient surplusfro m one croppe r year,wit hlittl eo rn omanagemen t or investment,s otha t there is little incentivefo rthe mt ogro wa secondcro po rt oinves t in increasedproduction .Tha t isparticularl y soi nth e caseo f absentee landowners . Inth e second case,farmer shav ebee n muchslowe r toadop t intensive croppingpattern san dHYV stha nprojec tplanner sassumed .Figur e1 givesexample so f therate so fadoptio no fETV si nth eboro/au san d amanseason s inth eG- Kan dEN D project areas.Bot harea shav e controlled drainage andirrigation ,an dhav e soilswhic har e suitable forHT V rice withirrigation .Yet ,i nth eG- Kare a(Phas e I), ittoo k more than 10year sfo rHTV st ocove reve n5 0percen to fth earea , althoughth etren dha sbee ncontinuousl yupward *I nth eEN Darea ,i t tookonl y twoyear st oreac h5 0percen tHTV s inth ebor o seasonan d eightyear st oreac h9 0percen tHTVs ,a t whichleve lth e proportion seemst ohav e plateaued;bu t inth eama n season,progres sha sbee n erratic,an d seemst ohav e plateaueda t7 0percent . Two lessonsca nb edraw nfro mthi sexperience .On ei stha t drainage and irrigationproject s shouldb eregarde d primarily as agricultural development projects,no t asengineerin g projects.Therefore ,agrono ­ mistsan d soilscientist snee dt ob e givena strongervoic e inth e planningan d implementationo fsuc hproject s- andtha tvoic e should be listenedt o!

- 149- DACCA-NARAYANGANJ-DEMRA PROJECT AREA 000oc / Boro Aman

-% HYV V—%HYV

Totol boro

' ,Totol amo n

- «7 6»« « 707 1 72 73r7V 7S 7« 77'78'7»'80' •!' S7'68'«9'70'7r72'73'7«"75 76'77'78'79'80Sr

000oc / GANGES-KOBADA K PROJECT AREA— PHASE- I •K.. Aus Aman

Total aman

% H Y V -

/ X' .... / • ti,f., «-r; «7 «r»« 7071 ' 72'7J'74'73'78' 7 7'78 7»' 10'81 «7 «8'6»'70'7I '72 73'74'75'7S'7 7'7«'7»'»o'»l

Figure I. Spread of HYV rice in two flood protected and irrigated areas

- 150 The second lessoni stha tagricultura ldevelopmen t involvesfarmers « Therefore,farmer sshoul db e consultedabou t thepracticalit y and acceptabilityo fth eplan sbein gprepare dfo rthem .I ti sth epolic y makerso rplanners ,no t thefarmer so rExtensio nofficials ,wh o should be blamed ifambitiou sprojec t targetsar eno tmet .I nth e caseo f both theG- K andDN Dproject s inBangladesh ,th eprojeo tauthorit y- compris ­ ingadministrator san dengineer s- ha splanne dthre eHT V cerealcrop sa yearfo rth e projects,withou t findingou t whethertha t iswha tth e farmerswan tt od oo rwhethe rsuc hcroppin gpattern sar epractica lfo r themt oadopt . Recent investigations indicatetha t such intensive cereal cropping patternsd ono t suital lfarmers *I nth eG- Kprojec tarea ,fo rexample , theaverag e sizeo ffar mholdin gi s2 h aan dth emajorit y of farmers are dependent onhired ,migran t labourfo rtransplantin gan d harvesting theau san dama nric e crops.Harvestin gan dthreshin g(b y bullocks) takes 1-2 monthso rmore ,whic hprevent sth equic kturn-aroun dwhic hth e additiono fa thir dHY V croppe ryea r wouldrequire .Moreover ,th e productiono ftw oRT V rice cropspe ryea r givesfarmer sownin g2 h ao r morea hug e grainsurplus ,abou t5- 6 timesthei rfamil y consumption needs.Ther e isn o incentivefo rthe mt ogro wa thirdcro ppe ryea r merelyt o satisfyth eplan so f theprojec t authority. Theexperienc e of theG- K projectan dth eChandpu rprojec t illustrates anothercommo nweaknes si nplanning :i.e. , ignoring the soilfactor s which influence farmers' choiceo fcrops .I nth eforme r case,th e soil surveyrepor t carriedou tfo rth eprojec t indicates2 0percen to fth e areaa sbein gunsuitabl efo rirrigate dric ebecaus e ofrapidl y perme­ able soils.Sve n iftha twer eno tapparen t fromth e soilsurve yrepor t - which,admittedly ,lik eman yreport so f itstim ewa smor e descriptive thanprescriptiv e- itshoul dhav ebecom eobviou sfro msit e examinations along thepropose dcana lalignments .le t theirrigatio n layout and croppingpatter nadopte dtotall y ignore that information.Th e main distribution channelsar ealigne dalon gth e most permeable soils,be ­ cause theyoccup yth ehighes tpar to f the landscape,a si srequire dfo r a gravity distribution system;an dtw o transplantedric e cropsa yea r are irrigated.No t surprisingly,wate rdoe sno t reachtail-en dareas , andonl yabou t 55percen t ofth e supposed commandare a actually receivesirrigation .

- 151- The Chandpur project plan expected farmers to grow two (or three) HTV rice crops a year. In fact, within the command area of almost 30,000 ha, farmers grew only 18,783 ha of boro rice in the 1981-82 dry season. They grew 3,507 ha of irrigated wheat and other dry-season crops; and a further 6,347 ha of dry-season crops (mainly chillies) were grown with­ out using irrigation. This reflects the fact - known to the farmers, and described in the soil survey reports - that a substantial area within the project boundaries has light—textured, permeable soils which are not well suited to irrigated rice cultivation in the dry season. Under pre-project conditions, some of those soils were intensively used for dry-season crops without irrigation, especially for chillies, which formed the area's most important cash crop. Obviously, farmers find it more economic to continue growing chillies (and other dryland crops) on such soils, without using irrigation, rather than to follow projeot plans blue-printed over their heads from Dacca (or from a donor's headquarters).

Agro—socio—economic surveys In this, the farmers are right. Projects should be tailored to suit farmers, not vice versa. However, it often appears as though project planners first calculate an economic rate of return which will justify investment in a project, and then fabricate an intensive cropping pattern to provide that rate of return. Admittedly, the planner's task is difficult. But it could be made easier if agricultural and socio­ economic surveys were made in advance, and if project plans were then based on a realistic assessment of the findings. Project planners raise no question regarding the need for detailed site surveys when dams and headworks are being designed. There needs to be a similar recognition of the need for detailed agricultural and socio-economic site surveys to be made before costly agricultural projects are designed. Agricultural surveys should provide information on the following subjects: a) soil patterns in relation to topography and hydrology, because most floodplain land is neither level nor uniform in soils;

- 152 - b)physica l soilpropertie s (actualo r predicted)i nrelatio nt oirrir - gation,drainag ean dnatura lmoistur estorage { c)crop san dcroppin gpattern si nrelatio nt osoils ,includin gevidenc e fromcrop spresentl ygrow xwit hirrigation ; d)far msize san dtenanc yconditions ; e)seasona lavailabilit yan dcos to flabour ; f)preferre d staplean dcas hcrops ,cro ppric erelationship s (including HIVversu straditiona lvarieties) ,an drelativ eproductio ncost san d returns,etc. ; g)opinion so fbig ,mediu man dsmal lfarmer so nwhic hcrop sthe ywoul d prefert ogro wwit hth epropose dprojec t improvements,an dwha t additional inputso r servicesmigh tb eneeded ;an d h)objections ,i fany ,fro mthos ewhos elivelihoo dmigh tsuffe ra sa resulto fprojec timplementation :e.g. ,fishermen ;farmer so n relativelyhig hlan dwh omigh tsuffe rfro mpreventio no fflooding ; andfarmer si ndepression swhic hmigh tbecom eperenniall ywater ­ loggedafte rinstallatio no f dryseaso nirrigation . Ifth efinding so f sucha surve yindicat etha tth epropose dprojec t wouldno tb eeconomic ,the ns omuc hth ebetter :th efund sca nb ebette r spentelsewhere .Ho wman yproject smus tther eb earoun dth eworl db y nowtha trepresen ta drai no nnationa leconomie sbecaus e theirplan s wereno tbase do na realisti c studyan dappraisa lo f theagro-socio - economicfactor s? In sucha situation ,projec tplanner s(o rGovern ­ mentpolic ymakers )hav efou ralternatives : a)aocep tth efinding stha tth epropose dprojec twoul dno tb eeconomic , anddiver tth epropose dfund st oa mor eeconomi cinvestmen t (preferablywithi nth esam e area); b)accep tth efinding san ddesign/redesig nth eprojec tt osui tth e physical,socia lan deconomi ccondition sfound ; c)accep tth efindings ,an dconside rwhethe rb yintensiv e extension activity,pric e incentives,improve dmarkets ,etc. ,farmer scoul d bepersuade dwithi na reasonabl e periodt oadop tcroppin gpattern s whichwoul dmak eth e projecteconomic ;i nthi srespect ,a pilo t scheme canb euseful ,bot hfo rth efarmer san dth eprojec tplanners ; d)accep t thefinding stha tth eproject ,a sproposed ,wil lno tb e profitable,an dprocee dwit hi ti nth eknowledg e that itwil lnee d

153 tob e subsidized,temporaril yo rpermanently ,i nth e national interest.

Firstgeneratio n problems

The lowirrigatio ncoverag e inth eG- Kprojec tare adu et o seepage loss­ es,an dth eerosio no f sectionso fth eembankment s inth eChandpu ran d BrahmaputraRigh tBan kprojects ,ca nbot hb eregarde da sfirs tgenera ­ tionproblems :i.e. ,the y result directly fromth e project design itself.Anothe rexampl e isth e cuttingo fembankment sb y farmerso r fishermenwh ofee ltha tth eprojec t isadversel yaffectin gthei rliveli ­ hood.I nth elatte rcase ,advanc e publiceducatio nabou t theeffect so f thepropose dproject ,paymen to fcompensatio no ra modificatio no f pro­ jectdesig ncoul dhel pt oavoi dth e problem. Anotherexampl e isprovide db y project designswhich ,i nseekin gt o optimizeeconomi crate so freturn ,preven t projectbenefit sfro mbein g providedt oa substantialnumbe r offarmer swithi nth e project bounda­ ries.Bot hth eEN Dan dChandpu r projectsprovid e exampleso f this.I n theEN Darea ,th eoptimu meconomi cpum pdrainag edesig nlef tabou t 10 percent ofth e polderarea ,i ndepressio n sites,subjec t todee pflood ­ ingfo ra wee ko rmor eafte rsustained ,heavy ,monsoo nrainfall ,suc h thatfarmer so nsuc hlan dcanno tris kgrowin gtransplante d aman (includingE7 V aman)o rusin gcostl y inputso nthei rmonsoo n season crops.Sustained ,heavy ,pre-monsoo nrainfal l inI98O-8 Ials o caused floodingwhic hdestroye dabou tone—thir do fth eHT Vbor o cropi nth e Chandpur projectare aan dprevente dfarmer sfro mgrowin gHT V ausi nlo w lyingareas .Th e solutionwoul d seemt ob et o designproject ss otha t theyoptimiz e thebenefit st ofarmers ,eve ni f thisrequire sacceptin g a lowerrat eo fretur n onprojec tinvestment .Tha tprincipl ewoul dsee m tob eparticularl y important inarea swher e smallfarmer spredominate ; (inth eChandpu r projectarea ,fo rexample ,th eaverag e sizeo ffar m holding isonl y0. 4ha) . The difficultyo f satisfying theneed so fal lfarmer swithi nth eCoasta l Embankment projectpolder sca nals o beregarde da sa firs t generation problemwhic hcoul dhav ebee nanticipated « The tidal landscape comprises shallowbasin swit hraise drim salon g creeks.Althoug hth edifferenc e in elevationbetwee nth ehighes tan dlowes tpoint sma yb en omor e than

154 60-100cm ,suc hdifference sca nb ecritica lfo rric efarmers ,especiall y forthos ewh owis ht o growdwar fHYVs .Tida l sluices inth e embankments provide drainage ofloca lrun-of ffollowin gmonsoo nseaso nrainfall » The problem is,ho wt oregulat e thedrainage « Ifth ebasin sar edraine dt o leave theoptimu mdept ho f watero nthe mfo rtransplante dama nseedlings , thehighe rfield sd ono t retainenoug hwater *O nth eothe rhand ,i f water isretaine d to satisfyth eneed so ffarmer so nth ehighe rmargins , thenth ebasi nlan dstay sto odeepl yflooded «A possible solution would bet oconstruc t lowinterio rembankment st oretai nwate ro nlan da t different levels,bu texperiment st o testo rdemonstrat e thispractic e haveprove dunsuccessfu l sofar ,becaus e of lacko fcooperatio nfro mbi g land-owners.

Secondgeneratio nproblem s

A numbero f problemsha sarise ni nembankmen t projects sometim eafte r theyhav ebecom e operational.Thes eca nb eregarde da ssecon d generation problemswhic hi tma yo rma yno t havebee npossibl e topredic t during projectdesign . Thefirs tproble mo fwhic hth eautho rbecam eawar ewa sth erapi dsilta - tiono f creeksoutsid e someo f thecoasta lembankments .Unde rnatura l conditions,tida lwate rfloodin gth e landtwic ea da yflow sslowl yof f thelan dagai na sth e tidefalls ,thu skeepin gth ecreek sflushed . Afterembankment shav ebee n completed,sluic egate spreven t tidalwate r fromenterin gth e poldera thig htide .Wate r inth e creeksstagnate sa t hightide ,therefore ,an ddrop ssom eo f it silt loadwhic h the slowflo w ofth efallin gtid e isinsufficien t topic ku pagain .Som e creekssilte d upwithi nthre eyear so fembankment sbein gclosed .Tha tno tonl yre ­ strictednavigatio no nth e creeks,whic hformerl yha dbee nimportant , but itals o causedwaterloggin g inth eadjoinin gpolder sbecaus eo f the restrictedoutflo wdurin gmonsoo n seasonrains .Hydrauli c studiesar e neededt oprovid ea solutiont othi sproblem . A secondearl y problemt odevelo pwa sperennia lwaterloggin g of some depressionsite s inth eG- Kprojec tarea .Tha tresulte dfro mexcessiv e seepage lossesfro mneighbourin gIrrigatio nchannel s located,a sdes ­ cribedearlier ,o npermeabl efloodplai nridges .Thi sproble m could become more seriousan dextensiv e iffull-scal e irrigationwer et ob e

- 155 introducedi nth edr y season;s ofar ,th eprojec tha smainl y provided supplementary irrigationi nth e pre-monsoonan dmonsoo n seasons,allow ­ ingth eMater-tabl et ofal ldurin gth efirs thal fo fth e dry season.I f theproble mwer et obecom e more serious- andi tis ,o fcourse ,alread y seriousfo rfarmer swhos e landi saffecte d- itmigh tb enecessar yt o introduce twomeasure st oreduc ewaterlogging :linin go f irrigation channelsalon gsection swher eseepag e lossesar emos t serious;an d if thisdi dno tprovid e asufficien talleviation ,th e installationo f tube-wellst olowe rth ewater—table * Withinth e last3- 4years ,ther eha sbee na growin gawarenes so f zinc (andsometime ssulphur )deficienc y inric e cropsgrow ni nth eEND , Chandpur,Baxisa lan dG- Kprojec tareas .Recen t studiessugges ttha t sulphurdeficienc ymigh teventuall ybecom e themor ewidesprea do fth e two*Th e eymptomsdevelo pwher eth erat eo fremova lo f soilnutrient s hasbee n increaseddu et oth e cultivationo fon eo rmor eHI V rice crops peryear ,an dwher eth e provisiono f irrigationfo rgrowin gbor oric e keepsth e soilswe tfo rmos to ral lo fth e dry season inadditio nt o the monsoonseason . Farmershav e foundtw o solutions.On e ist ogro wa quickmaturin gwinte r crop— e.g., mustardo rpulse s— before plantingboro .Tha thelp sth e topsoil todr you tan dbecom eoxidize dfo ra time ,whic h increases zinc and sulphuravailability .Th e second solution ist oad d zinc sulphate fertilizer.Th eus eo fthi sfertilize rha sincrease dremarkabl ywithi n thefirs t 18month stha t itha sbee nmad eavailable ,t o theexten t that a consultant examiningth e problemearl y in 1982wa sabl e tofin dlittl e visible evidenceo fth e deficiencyi nth eDN Dan dChandpu r project areas:mos tfarmer sappeare dt ob eusin g thefertilizer .Farmer sclearl y aremuc hles sconservativ e aboutadoptin gne wpractice s thanthe yar e popularly condemneda sbeing ,a tleas twhe nther ear eobviou san dsimpl e remediesavailable . Acidsulphat e soils,fortunately ,provid e arelativel y minorproble mi n Bangladesh.Suc hsoil soccu rpatchil y onth e saline tidalfloodplains . Theacidit y problemi smos t severean dextensiv e inth esouth-east , where some soilshav e goneou t of cultivation.However ,a substantial areao f suchempoldere d soilsi shighl y productive formakin g salt.O n theGange s tidalfloodplain ,th e acid sulphate problem isles sseriou s

156 becauseGange ssil t inth eriver sdurin gth efloo dseaso ncontain slin e whichcoul dh euse dt oneutraliz e theacidity ,i fnecessary .

Landus e regulation

Twoothe r secondgeneratio n problemshav e recentlyhee n identified: encroachment ofsettlemen t ontoflood-protecte dland ;an dth e conversion ofpolder sfro magricultura lus et o shrimpfarming . A recentFA O consultant's studyo f seven,scattered ,rura larea s showed that,i ngeneral ,settlemen tan drelate dnon-agricultura llan dus e expandedb yonl y 0.8 percent between 1952an d 1974,eve nthoug hth e humanpopulatio nexpande db ya naverag eo f5 8percen t duringtha tperi ­ od.Examinatio no fairphoto sshowe dtha tth epopulatio nha dexpande d almostentirel ywithi nexistin g settlements,b yreducin g theare aunde r treesan dwast e land.Tha t waspartl y explainedb yth e seasonalflood ­ ing,whic hmake si tcostl y tobuil da ne wearthe nplatfor mabov e flood- level,an dpartl yb yth e farmers'natura l inclinationt opreserv e their landfo ragricultura l production.However ,i nth efirs t 10year sfollow ­ ingth e completiono fth eDN Dpolde routsid eDacca ,th eare aunde r settlementan d industrydoubled ,an dth e trendobviousl y is continuing rapidlya sfarmer s(an dsuburba nnon-farmers )buil d individualhouses , scatteredove rth ewhol e areainstea do fwithi nexistin gsettlements . Withinth enex t 10-20years ,i ti sprobabl e thatth epolde rwil ln o longerb ea viabl eagricultura l project;i twil lb ea suburbo fDacca .

There isa dange rtha ta similarspraw lo f settlement couldeventuall y negate the objectiveso fothe r polderprojec tareas .(Eve npre—project , 28percen t ofth eChandpu r projectare awa soccupie db ysettlements) . There isth e risk,too ,tha tth e spreado f settlement onth e flat (i.e.,withou tmakin ghig h platforms)coul dlea dt ocatastrophi c loss of lifean d property if,fo ran yreason ,a polde rembankmen t were tob e breached duringth efloo d season.I t seemsessential ,therefore ,tha t thesprea do fsettlement s (and industry)withi nfloo dprotecte darea s shouldb eregulate d sotha t theminimu mamoun to fvaluabl e agricultural land istransferre d tonon-agricultura l uses,an ds oa st o minimize the risko f catastrophic casualtiesan dpropert y damage ifa nembankmen t is breached.A t present,th eGovernmen t ofBanglades hha sn o practical

157 - legal means to regulate land use. That is an omission which needs to be rectified without delay* The same lack of land use regulations is permitting powerful businessmen and land owners to convert agricultural polders in parts of the Coastal Embankment project area to shrimp farms* The process is simple. The embankment is breached, allowing brackish water to flood the land and shrimps to enter for breeding and growth. The salinity either prevents the farmers from growing their traditional, single, ajnan crop, or it greatly reduces aman yields and production« It is estimated that more than 4,000 ha of land have so far been lost to agriculture in this way in south-western polders; no figures are readily available for losses in the south-east. Shrimp farming is highly profitable to the powerful individuals who control it. Shrimp exports also earn the country valuable foreign exchange. But the effect on small farmers and agricultural labourers can be disastrous, and the breaching of the embankments negates the purpose for which they were constructed. A thorough socio-economic study is needed to determine the net social and economic gains and losses. Tech­ nical studies also are needed to determine whether shrimp farming and crop production can be combined or can be practised on separate land. Whatever the findings might be, it seems essential that either the project authority, a locally elected council or central government should have the power to regulate land use in the polders in the greater public interest.

Futureneed s

Bangladesh's population of 92 million is estimated to need 14*5 million tons of foödgrains per annum. Taking into account seed, feed and waste, about 16 million tons are needed. Each year, population growth adds a further 400,000 tons to the requirement. By 1^84-85, the target food- grain production is 18-20 million tons, including provision for building up reserve stocks. The country presently produces 14-15 million tons annually. The range in figures given reflects annual fluctuations in production due to good and bad harvests. Production is about 10 percent below requirements; in the past 5 years, annual imports have averaged 1.5 million tons. In addition,

158 a widerang e ofothe r foodan d cashcrop si sgrown ,mainl y without irrigation.Suc h crops include jute, sugarcane,banana ,tea , potato, pulses,oilseed san d spices. To-date,majo rembankmen t projectshav e contributed anestimate d1 million tons (net)t oannua l foodgrain production.Tha t ismuc h less thanwa sexpecte d when the projects wereplanned .I trls o ismuc h less than the 2.5 million tons (net)annuall y which small-scale pump and tube-wellirrigatio n schemesprobabl y have contributed* The majorembankmen t projects included inth e 1964Maste rPla n have been slowt oattrac t donor investment.Apar t fromtechnica l problems described inth e text above,donor shav e been reluctant to take up suchproject s because of the high capital costsan dth e long gestation period before benefits appear.Small-scal e projects have therefore attracted more support because ofth e lower investment cost perhectare , the quicker returnsan d the more widespread distribution ofbenefits . Included inthos e smallproject sar e anumbe r of so-calledearl y imple­ mentation projects,usuall y providingfloo dprotectio n and/or irrigation (but usually not polders) to areaso f upt o 6,000ha « Undoubtedly, ifth e country's population continues to growa t current rates- doubling inabou t 30year s- then major polder projects (perhaps includingestuar y closures)wil l eventually beneede d soa st o enable highyieldin g transplanted aus and amant o begrow n on most of thefloodplai n land,7 0peroen t ofwhic h currently isto o deeply flooded for them to be grown during the monsoon season.Irrigatio n willals o be needed to extendHT V cultivation inth edr y seasonan d make production more reliable inth emonsoo n season.S y theyea r 2000A.B. ,i t is estim­ ated that production must increase to 25millio n tonst o satisfy the population's consumption needs. Regarding suchprojects ,th enex t 5—10year s during which attention is concentrated on small-scale methodsnee d tob e used to make anexhaus ­ tive study ofexperienc e gained from polder projects whichhav e been oompleted.Thos e studies should includeno t onlyengineerin g considera­ tions, but- at least equally important - agricultural, social and economic considerations: what has succeeded; what hasfailed .Arme d withmor e comprehensive information, planners should then be able to design more realistic and profitable projects whichar e better tailored

- 159 - to tbs farmers'needs .Tha t willrequir e therecognitio n that engineer­ ingwork sar eno t an end inthemselves » They are amean st o anend .I n Bangladesh, that end isagricultura l development, asreflecte d inopti ­ mum improved landus e anda wel lfe d population.

Conclusions

Bangladesh's experience withmajo r embankment projects suggestsa number ofprinciple s whiohma yh eo fwide rrelevance ,especiall y in developing tropical countries* 1.Wher e embankment projectsar e undertaken primarilyt o increaseagri* - cultural production, they should be regardedprimaril y as agricultural development projectsrathe r thanprimaril y asengineerin g projeots* That implies that: a)soi l scientists,agronomists ,agro-economist san dagricultura l exten­ sion specialists shouldb egive n a moreresponsibl e role in project identification, design,appraisa l and implementation; b) inarea swhio halread y are cultivated, the opinions ofa representa ­ tiverang e offarmer s inpropose d project areas shouldb e sought in advance regarding feasible croppingpattern swit hpropose d projeot inputs; c)wher e a projeot wouldgreatl y alter existing agro-eoologicalcondi ­ tions, (asusuall y will be the oase with embankment projeots), possible new cropso r croppingpattern s shouldb e testedan d demon­ strated inpilo t areasbefor e the fullprojec t isimplemented ; and d)objection sfro m those whose livelihood might suffer asa resul t of project implementation shouldb e consideredwit ha vie weithe r to modifying the project design soa st o remove their objections or to provide them withadequat ealternative s or oompensation. 2.Becaus e embankment projeotsusuall y are expensive, especially when the;,includ epum p drainage sndirrigation , they should be regarded as a development mode of last resort.Tha t means thatGovernment s should examine and use alternative, cheaper,agricultura l development modes wherever possible,unti l embankment, etc.,become s the most economic mode remaining available. 3.Geomorphological ,hydrologica l andhydrauli c studies shouldb e made todetermin e the optimum location of projeot embankments and irrigation/

160 drainage headworksalon gaotiv e river oha"nelsand .i ntida lfloodplaine , taking into aocount the predicted effects ofprojec t workso n river flow and sedimentationoutsid e embankments ando n drainage within embankments. 4« Irrigation obannelsshoul db e sited anddesigne d so as to minimize seepage losseswhio hmigh t cause waterloggingan dpreven t irrigation benefits from being providedt o tail-endareas * 5*Especiall y inarea swher e smallfarmer s predominate,project s should be designed so ast o minimize landacquisitio nfo r project worksan d so ast o maximize thenumbe r offarmer swh o benefit, even iftha t means ac­ cepting a suboptimum economic rate of return. 6.Soi lan d crop conditions ondifferen t agro-ecological land types within project areas shouldb e monitored regularly soa s to provide early warnings ofan y physical, chemical orbiologica l problems which maydevelop .Relevan t studies should bemad e to findpractica l solu­ tions, including solutions whiohmigh t require the modification of project design oroperation .Similarly ,agro-economi c surveys shouldb e made regularly,an dappropriat e changesmad e inprojec t design, opera­ tiono r charges soa s to ensure that bothfarmer san dprojec t authori­ ties canaohiev e profitable returns. 7.Eithe r atnationa l ora t project level,lan dus e regulations should be madean d enforoed which willensur e that settlement and industry do not spreadunnecessaril y onto valuable agricultural land oront o sites where disastrous losses of lifean d property might occur inth eeven t ofa nembankmen t beingbreache d by floods;also , soa st opreven t or control formso f land use whiohconflic t with project objectives«

161 162 SOCIO-ECONOMICAN DPHYSICA L PLANNINGASPECT S

- A.K. Constandse. From spontaneous settlement to integrated planning and development - J.H.M. Kienhuis. Themanagemen t ofpolder s inth e Netherlands - A. Sfeir-Younis. Economic aspectso f soil conservation programs inLDC' s

- 163 164 FROMSPONTANEOU SSETTLEMEN TT OINTEGRATE D PLANNING ANDDEVELOPMEN T

A.K.Constands e Rijksdienstvoo r deIJsselmeerpol - ders,Lelystad ,Th eNetherland s

Abstract

Thereclamatio n ofne wland ,whic h isuninhabited ,involve s internal colonization implying theestablishmen t ofa ne w society.I nth ebegin ­ ningth ereclamatio nproject swer ecarrie d outb yprivat e corporations and therewa sn oclea r settlementpolicy .Eve nwhe n inth e19t hcentur y theStat e tookresponsibilit y forth eoperation sn osettlemen tpolic y ofan y importancewa sdeveloped .Durin g theexecutio no fth eIJsselmeer - polders-project inthi scentur y aplannin g anddevelopmen t systemwa s built up,however ,tha t takescar eo fdetaile d integrated plans,take s responsibility forth epreparatio no fth eland ,fo r settlementpatterns , forconstruction ,fo rth eguidin go f immigration,th ecreatio no fjobs , andth eharmoniou s integration ofth epla n inth enationa lplannin g goals.

Theorigi no fpolder s ist ob efoun d inth ehuma n attemptst oprotec t landagains t flooding,wit hth eai m tomak e landtha tcoul db euse d temporarily only,int o landtha t could beoccupie d permanently and safely. Inth eNetherland s theseattempt s started abouton e millennium ago. Why theseheroi c effortswit hprimitiv e tools insuc ha dangerou shalf - drowned countrywer emad e isa n interesting question,bu twil lno tb e

165 answered here.No tth ecause sbu tth eeffect sar erelevan t inthi s context.Ou to fthi sco-ordinate d movingo feart hwhic henable dth e peoplet ocontro lth emovin go f water,technica l aswel la sorganizationa l skillswer e developed,whic h created aselfconsciousnes si nmatter s ofwatercontro l thatforme d thenecessar y basisfo rth e development ofplan sfo rdrainag e ofne w land,lan d thatwa sno toccupie dbefore . Insmall-scal e reclamations thisdi dno talway s implyne whuma nsettle ­ ment:th ereclaime dlan dwa sjus tuse dt oenlarg eth eexistin g farmso restates . Inth eNort ho fth ecountr yi t isusual ,u pt oth epresent ,tha tth e borderlineso fa farm ,standin g perpendicularly onth ecoastline ,ar e elongated intoth ewate ran dal l the landtha twil leventuall y bere ­ claimed, lyingbetwee nthos e lines,belong s inprincipl e totha tfarm . Even ifa concerte d effortwa snecessary , sucha sth edrainag eo fa lake,fo rwhic hwindmill sha dt ob ebuil tfo rpumpin gth ewate rout ,i t mightwel lb etha tth ereclaime d landwa sfarme db y thepeopl e living onth eborde r ofth eforme rlake .

When thedrainag eproject sbecam e largeran dtechnicall y moresophisti ­ cated,considerabl e investmentswher enecessary ,whic hcoul dno tcom e from local sources.A sa consequenc e theproject s cameint oth ehand s ofmanagers ,planners ,an dwer e considered asend si n itself.Farm s were established,village scam eint oexistence ,peopl e from elsewhere weremove d in,sometime s from adjoining areas,sometime s from larger distance,sometime s individually, sometimes ingroups . Although the inhabitants ofth ene w land didno t comefro mver yfar ,mos t often fromwithi nth e Netherlands,whic h isa rathe r smallcountry , a fact istha tthes epeopl e came together inne w circumstances,wher e everythingha dtob ebuil tu pfro mscratch ,wher ea ne wsociet y hadt o beformed .A ssuch ,th enam e 'internalcolonization 'whic hha sbee n givent o suchprocesse s isquit eadequate .Als oth enam e 'pioneer' attributed toth efirs tsettler swa sno ta nexaggeration ,becaus eth e lifeo fth efirs tan d sometimeseve nth esecon dgeneratio n wasno ta n easy one.I nth e 17thcentur y thecompanie swhic hundertoo k thework s were formed bymerchants ,urba npeople ,wh owante d landbu twh odi d notkno who wt owor k itan d sometimes appointed unskilled peoplet o continue theexploitatio n ofth elan d after drainage.Furthermor eth e landwa softe nbadl y drained,a sa consequenc eba dharvest scam eabout .

166- Peoplewer e struckb ydiseases ,lik emalaria ,i nunhealth y conditions atth ebeginning . Inth e19t hcentury ,whe nsom e largedrainag e schemes,wit hmoder n techniques (steam engines instead ofwindmills )wer ecarrie d outb y theStat e andno tb yprivat ecompanies ,th e living-conditions forth e peoplewer eno ta tal lgoo di nth ebeginning .Th eStat e carried outth e worksfo rreason so fsafety-protectio n ofth earea ssurroundin gth e lakes- an dwa sno t interested inth eexploitatio n ofth e land.Afte r initialdrainag ean da roug hparcelizatio n theacquire d landwa ssol d assoo na swa spossibl e andn oattentio nwa sgive n towha thappene d further.Thi swa sth ecas ewit hon eo fth e largestdevelopment s inthi s country,th eHaarlemmermeer ,a nare ao f20.00 0ha ,i nwhic hno w Schiphol-airport islocated .Prosperou sa sth eregio n isnow ,ver ypoo r itha sbee n inth efirs ttwent yyear so f itsexistence ,becaus eo fba d drainage,lac ko fgoo d organization ofth ebuildin go fth ene wsociety , resulting inba dhealth-care ,forma leducation ,housin g andtransporta ­ tion. When inthi scentur y theDutc hgovernmen tdecide d tocarr you tth e largestreclamatio nprojec t everundertaken ,i twa sunderstood ,o nbasi s ofth eaforementione d experiences,tha ta sth egoa l shouldb et odevelo p notonl yne w land,bu tals oa prosperou san dharmoniou s society,i t should take fullresponsibilit yfo rth edevelopmen tproces sa sa whole , notonl y forth etechnical ,bu tals o forth esocia lan d economic as­ pects.Thi s idea ofmor e intensive intervention by theStat ewa sno t only inspired by the ideatha tth emistake so fth epreviou scentur y shouldb eavoide dnow ,bu twa sals oa nexpressio n ofth ecomin go fth e welfare-state. TheStat eha dt opla y inthi swa y adua lrole .A sowne ro fth ene wland , developed withpubli c funds,i tha d thedut y tostriv eafte rgoo d economic management ofth earea .I tshould ,jus ta san yprivat eentrepreneu r try tomak eprofit .A sguardia no fth ewelfare-stat e itha d toprotec t the inhabitants againstmisfortun e and topromot epubli cwelfare .Thes e tworole sar eno talway seas yt ocombine . The firstrol ewa s inth ebeginnin g considered asth emos t important one.Th elan dwa smad eread y fornorma l cultivation byth eDevelopmen t Authority.A lan dallocatio npla nwa smade ,wit h fixed sizesan dtype s

167- offarms .Th elan d remained property ofth eState ,th e farmbuilding s wereconstructe d byth eState .Th e farmerswer ecarefull y selectedi n order tob esur etha ta ver y capablegrou po fpeopl e would tillth e land inth e newarea .I fth emai nai mo fa reclamatio nprojec t ist o increase theagricultura lproduction ,the nthi s isa goo dpolicy . Iti s thesam epolic ya swoul db eapplie db yaprivat e landowner:tr yt ofin dth ebes t tenants.Thi spolic ymad ei tunnecessar yt omak eextensiv eeducationa lan d trainingprogramme sfo rth esettlers .The ywer eread yfo rth ejob .Thi si ssta ­ teds oexplicitel ybecaus ei nman yforeig ncase s themai nproble m isho w toteac hpeopl et omak e thebes tus eo fth ene wopportunities .I nthos e casesth epeopl ear eno tselected : theyar eth eone swh oar eentitle d forsom ereaso n toreceiv e apiec eo fland . Thesecon drole ,bein gth eguardia no fwelfare ,i sles seas yt odescribe . Eveno nth ematte ro fth efarm s itself,th ebasi so fth eeconomy ,ther e werenex tt oeconomica l also socio-political factorstha tplaye d arol e indecision-making .Fro m apurel y economicalviewpoin t itwoul dhav e beenpossibl e tocalculat ewhic h typeo ffar mwoul dgiv e thehighes t profit.Bu tthi swoul dno tgiv enecessaril y thehighes t socio-economic advantage onth enationa l level.Fo r thatreaso n arathe r complicated systemwa sdeveloped ,resultin g ina mi x ofsmalle ran d largerfarms , giving opportunities todifferen tkind so ffarmers . Butoutsid e thedirec t sectoro ffarmin g theplannin gbecam eals omor e 'human',mor e directed toth ebuildin g ofa societ y thant oth eeconomi c development only.Th efarmin gpopulatio n shouldno tonl yhav egoo dfarms , butther eshoul db eals o service-centres,good ,housin gfo rth eworkers , there should beshops ,schools ,churches ,medica l services,recreatio n facilities, libraries.An dal lth epersone l employed inthes e services should havea goo dbasi s forexistenc e andth eservice s shouldhav e a good quality. Inretrospec t this soundslogica lan d simple.A tth etim eo fth efirs t development inth eIJsselmeerpoldersproject ,hal fa centur y agonow , itmean ttha tal lkind so frelation sbetwee n socialfact sha d tob e studied and quantified:ho wman y customers doesa bake rnee d tomak e a living;ho wofte ndoe sa n averageperso nborro w aboo kan dho wman y kilometersh ewil ltrave lt oge t sucha book ;youn g loversnee dsom e wood tomak ewalk s in:ho wman yhectare so fwoo d should beplante d to

168- satisfy theneed so fa certai n quantity of lovers? Thisdi d notonl y provokeresearc hneeds ,bu t itals oencouraged ,eve n necessitated,government-interferenc e ina numbe ro ffield stha tha d alwaysbelonge d toth eprivat e sphere.Standard s andnorm sha d tob e found fora numbe ro fimmeasurabl ethings . Ofcours eresearc h andnormsettin gha d imperfactions,no t inth elas t placebecaus e social changeremaine d fora larg epar tunpredictable , buta nadvantag e ofal lthi sresearch-wor k and striving after integrated, comprehensive planningwas ,tha tth eunderstandin g about interdependencies inmatter so fsocieta l developmentwa s improved and thatbecaus eo f thatbette rplannin g systemscoul d bedesigned . From thesingl egoal ,ho wt okee pth eare adr yan d safe,th egoa lt o makeprofi tfro magriculture ,no wth egoa lwa st ogiv epeopl ea goo d life.

Asagricultura l areasth epolder s couldb econsidere d asbein ga nen d in itself.O fcours eth einterna l colonizationha d alsoa sa goa lt o solveproblem so nth emai n land:farmer s leaving forth epolder sfree d space forothe r formso flanduse ,o rfo rimprovin g thefarm-structur e inovercrowde d areas.Th epolic y ofselectio n ofapplicant sfo ra far m inth epolder swa s inlate ryear seve ngeare d totha tpurpose .Bu tth e developmentswithi n theprojec t werenevertheles shappening s ina mor e or lessclose d regional-economic system. Because inothe rpart so fth eworld , inman y ormos tcases ,polder s aredevelope d foragricultura l purposes,som emor eattentio nwil lb e given totha tpar to fth ehistor y ofth eIJsselmeerpolders . Ifagricultur e isth emai n sourceo fproduction ,th echange s inagricul ­ turehav e far-reaching influenceso nth esocio-spatia l system. Inou r caseth emai n changewa stha tth erespons e ofagricultur e toth ecost - price squeezewa sth ereplacemen t oflabou rb ymachines ,whic hmean t thatther ewer e lesspeopl e onth e land.Les speopl eo nth e landmean sa lowerdeman d forservices . This lowerdeman d forservice swa squit eproblematic ,becaus e itwa s only quantitatively lower,qualitativel y itbecam ehigher .Goo d schools werewanted , shopswit h avariet y ofware swer erequested .Thi sproble m could within the closed system onlyb esolve db y reducing thenumbe r

- 169- ofcentra lplace s andacceptin g the largerdistance s from theperipher y ofth ecatchmen t areast oth ecore .Becaus eo fth efac ttha tth e farmers were inth epositio ntha tthe y couldposses son eo rmor eprivat e cars the increase indistanc ewa sacceptable ,bu to fcours eno tideal . Theremarkabl e thingabou tth eprojec to fth eIJsselmeerpolder si stha t iti spossibl e tose eth eeffect so fsocio-economic -chang ean d ofdeve ­ lopment inplanning ,rea llife ,becaus eth epolder shav ebee n constructed oneafte rone ,wit htime-lag s longenoug ht ose e change clearly:year s ofdrainag ebein g 1930,1942 ,195 7an d 2968. Inth efirs tpolde rth emai n ieffortha sbee npu tint oa goo d landuseplan foragriculture :rectangula r lots,goo d roadconnections,i nsom epart seve nwaterconnections .Bu t apla n fora balance d settlementpatter nwa sno tmade .I twa sexpecte d that likei nth epas ta troadcrossing sservice swoul d springup .O fcours e thiswoul d havehappened ,bu tno t inth eorderl ywa yan dwithou tpersona l dramasa swa sth enor m inthi sera .Therefore ,late rth egovernmen ttoo k careo fth eestablishmen t ofvillages .I nth esecon dpolde rth elesso n wastake na theart :nex tt oth ecarefu lplannin g ofth eagricultura l landuse,th esettlemen tpatter nwa sdesigne d onbasi so fextensiv e studies oncatchmen tarea so fdifferen tkind so ffunction s ando ndistance sfro m theperipher y ofa villag eare at oth ecentr ewhic hwoul d beacceptable . Theresul twa sa hierarchica l pattern ofa regiona l centre inth egeo ­ graphicalpoin to fgravit y anda circl eo fte nvillage saroun dit . Already duringth eperio d ofexecutio no fth epla n itbecam eclea rtha t thedynamis m ofsocieta l developmentwa sunderestimate d andtha tth e systemwa sto ostatic :th evillage s remained toosmall ,th eservice s couldno tfunctio n inth eprope rwa y fortha treason ,an dbecaus eo f an immense increase inprivat emotorizatio n distances countedmuc h less asa limitin g factor,whic h caused thatth eregiona l centregre wfaste r thanwa sexpected .A paralle lo fthi swa y ofplannin g ina close dsyste m canb efoun d inth eLakhis hregio n inIsrae l (nota polde rbu ta forme r desert).Th esam ehierarchica l pattern setu p inabou tth esam e time andno wa prosperin g regional centre- Kyria tGa t- ha sgrow nwhil eth e villageshav ehardl y afunction .

Inth ethir d polderth eresult so fth echange sar eclearl y demonstrated. Againa regiona l centrewa splanned . Thenumbe r ofvillage swas ,i n comparisonwit h theforme rpolder ,greatl y reduced,fou r insteado f

- 170- tenan do fthes e£>u rori ytw owoul d bebuilt .Th eaverag e sizeo fth e farmswa s increased,th enumbe ro fpeopl eemploye d inagricultur ewen t downan ddow nan dsoo ni twa srealize dtha tth esyste mo fenlargemen to fscal e could notg oo n forever.Th eclose d system wasbroke nu pb yth edecisio n nott obuil d housesfo r localdeman d only inth e twovillage stha twer e realized,bu tjus tt obuil d andallo wpeopl e from elsewhere,wh ower e noteconomicall y tiedt oth earea ,t obu yo rren ta house .Becaus eo fa shortage ofhouse san d the desire ofman ypeopl e toliv eoutsid eth e big cities ina quie trura l environment,thi spolic ywa squit esuccess - full. Itwoul d be interesting tokno who wthi sproces swoul dhav edevelope d inth efollowin gpolder s ifagricultura lus ewoul dhav ebee nremaine d themai nfunction . But thiswa sno tso .Aroun d theyea r 1960th eperio do fth eIJsselmeer - poldersprojecta sa n isolatedagricultura l project ended.Th epolder s comingneare r toth eurba n concentrations inth eWes to fth ecountr y(th e Randstado rRi mCity )wer emor ean dmor eregarde da sacompensatio n forth e scarcity ofspac e inth eurba nareas .Th eborderlakes ,designe d atfirs t forgeohydrologica l reasonsonly ,becam e ina shor ttim erecreation - areaso fnationa l importance,fo rswimming ,fo rsailing ,developin ga demand behind thedyke sfo rarea swher e campings and holiday-bungalows couldb ebuilt . Ofmuc hmor e importance hasbee nth edecisio n tochoos e thepolder s asth elocatio n oftw one wtowns .Th efirs tone ,Lelystad ,coul db e regarded asa n expanded townbecaus e thepolder swoul dhav eneede da larger centre,a kin do fprovincia l capital,anyway .Withou t the 'task' togro wou tt o100.00 0 inhabitants,som e 30.000woul d have livedi n theplac e ifth eregiona l system hadremaine d closed. Thesecon d one,Almere ,designe d for250.00 0people ,i sa pur e satellite ofAmsterdam ,bu t isplayin g roleo fcours e inth epolders . Ina rathe r shortperio d changeshav etake nplac ewhic hhav ea tremendou s effect.Wher e asa continuatio no fathousan dyear s0 id traditionth e agricultural spaceo fth eNetherland swoul db e increasedwit habou t 10percent ,no w theregio n issee na sth ehabita t forhal fa millio n ofpeople . Inth eDutc hterm shal fa millio n ofpeopl e isa sufficien tnumbe rfo r

171 forming ane wprovince ,bu tthi s isprobabl y noto fgrea t interestfo r a foreignaudience . Ofmor e importancema yb etha tth eagricultura l function,whic hha sbee n themos t importantdurin gth eperio d ofreclamation ,i sno wbein gattac ­ kedb ya thir dne welement :nature .I nthi scrowded ,urbanize d andin ­ dustrialized country there isa genera l feartha tnatura l areas,typica l forth e lowlands,wil ldisappear .Therefore , there isa stron g (political) movementtha twant st okee ppart so fth edraine dlan d asi ti s afterreclamatio n and doesno twan ttha tth efift han d lastpolde r ismade ,becaus ea s a lakethi spar to fth eterritor yha smor evalu e thana sland . Somepeopl e state thatno tdoin gthings ,no ttransformin gth eenviron ­ ment isth eultimat ewisdo m aftera perio d ofruthles s destructioni n order tomak eprofit .Other sthin k thatthi sattitud e isth eresul to f a stateo fsuc hhig hprosperity ,tha tpeopl e thinkthe y canaffor dt o leavething sa sthe yare .Probabl y there issom etrut h inbot hstatements . Anyway, iti sa curiou sphenomeno n tose etha tther e issuc ha resistanc e toth eattemp t tocreat ene wspac efo rhuma n lifes onea r toa nare a where sixmillio npeopl e livean dwh ohav ea shortag eo fspace .O fcours e thewate ra ssuc hi sals ospac efo rhuma nus ean dthi si s recognized byth e facttha tth eborderlake so fth epolder sar edesigne dwide rtha ni s necessary forhydrologica lpurposes .

So, asha sbee n said:eac hpolde r isa nexpressio n ofth etim e inwhic h itha sbee nconstructed ,eve nth e laston eb yno tbein gconstructe dyet ! Itshow stha t themai nvalu eo fthi stechniqu e ofdrainin g isth e acquisition ofspace ,whic h canb euse d forman ypurposes .Thi s isdemon ­ strated inth eNetherland sver y clearly,becaus e this issuc ha densel y populated country. Also theolde rpolders ,whic hhav eoriginall y been made forth eacquisitio n ofagricultura l land,ar eofte nuse dno wfo r otherpurposes :industry ,residentia l quarters ofth etown ,o rairports . Thefac ttha tthes epolder sar es oclearl y aproduc t ofthei r time is probably typical forpolder sa ssuch ,becaus epolder sar e flat,ar e ratherundifferentiated , havehardl y anyhistorica l landmarks,an dgiv e therefore theplanner s ahig h degreeo ffreedo m fordesigning .Thi si s in itself fascinating,bu t itgive sals o aheav y responsibility andth e absenceo fguideline spresen t inth eexistin genvironment ,cause sdecision -

- 172- making tob eofte n laborious. Onth eothe rhan d thefreedo m ofth eplanner s islimite d byth ewishe s andneed so fth e immigrants.I fimprovement so fa certai nkin dar e wanted,the nthe y canb erealize d -withi nreaso n- i nth ene wpolders , but ifth eimmigrant swan tt omaintai n orreproduc e their culture inth e newenvironment ,the nther ewil lb en ofundamenta l innovation.Althoug h there ismuc h societal change,thi schang eattract ss omuc hattentio n and isdescribe d atsuc hlenght ,tha tther e ishardl y anyawarenes so f continuity.T -fon estudie sth eso-calle d newsociet y onth ene w landtha n iti ssurprisin g tose eho wmuc hcontinuit y there is.Fo ra par tthi swil l bebecaus eanumbe ro f culturalelement sfunctio ns owel ltha tther ei sn o needfo rchange ;fo ranothe rpar ti tma yb eexplaine d bytraditio n (whichca n berationa l aswell) . Remarkable isth econtinuit y inth esyste m of agriculture.Ther e isa nenormou schang e intechniques ,th eproductio n anath eproductivit y havegrown ,bu tth etype so ffarms ,eve nth esiz e and formo fth e farmssho wa resemblanc ewhic h isstriking ,whethe ron e looks inth esixteent h centuryBeemster ,th eeighteent h centuryHaarlem ­ mermeero rth epresen tday sIJsselmeerpolders . This internal logico fth edesig nan ddevelopmen t ofth efirs tpolder s disappeared withth ecomin go fth ene wtowns .Th enumbe ro finhabitant s wasn olonge r theresul to fth eproductivit y ofth eland ,bu tbecam e a target in itselfan d theresul to fdecision san ddevelopment s outside theregion . Thismad eth eplannin gproces smor e complicated andmor e a parto fth e nationalplanning . Thetas ko fth edevelope rwa sn olonge ronl yt oequi pa regio nwit hth e necessary system ofservice san damenities ,bu tals ot opromot ean d create theresource s formakin g alivin ga swell :b yreplacemen to f activities and jobsfro m elseweher (overspill from thecities )o r establishment ofne wactivities .Althoug h thisbuildin g ofne wtown s wasstarte db y thesam eorganizatio n thatdevelope d thepolder sa sa whole,thi sactivit y isi nfac tn o longertypica l forpolders ,excep t thatth estar tha d tob emad e from scratch:n o infrastructure ofan y kind available inth ebeginning .Becaus e thesene wtown swit hthei r fastgrowt h involvea larg ebuildin g activity,ne wway so ffinancin g had tob e found,th efund scomin g from different andmostl yprivat e sources.Thi smean ttha tmor epeopl e and institutionswer egoin gt o

173 participate inth edecision-makin g process.Thi smad ematter smor ecom ­ plexan dth etimin g inth esyste m ofnetworkplannin g morevulnerable . Asbuildin g ofhighways ,constructio n ofa railway ,th ebudge tfo rhousin g etc.ar eal l subjectt odifferen t sphereso fdecision-makin g andhav e theirow nsequence so fpriorities ,regiona l comprehensive planningbecome s difficult. Looking atthi scomple x situation itbecome sal lth emor eclea rwha tth e adventagesar eo fth eformul ao fth eIJsselmeerpoldersproject :ownershi p ofth e land,planning ,developmen t andmanagemen t inth e initialstag e inon ehand . Ofcours ea goo d organization isno ta guarante e forsucces si nal l respects.Th egenera l economic situation ina country ,th epolitica l climate,th echange si nvalue-orientation ,hav e quitea ninfluence , especially on long-term planning and adevelopment-organizatio n hast o takethes e factorsa sdata .Thi sca nb esee n inth epresent :i ti spossibl e tobuil d ane wtown ,t odevelo p ane w society onne w land,bu t ifunem ­ ployment isgrowin g inth ecountr y and inneighbourin g countriesalso , itcanno tb eavoide dtha tthi sphenomeno n occursals o inth ene wtowns . But the interesting factremain s thatpolder sa ssuch ,b yprovidin gspace , havealway sa value .Tha ti stru efo rth eol dpolders ,i twil lals ob etru e forth enew .I ti squit epossibl e thatther ewil lb en onee d formor e newtown s inth efuture .The n iti sgoo d torealiz etha tw edi dno tmak e polders inorde r tohav e space forne wtowns ,bu ttha tw efoun d aplac e forne wtown sbecaus e therewer ene wpolders .I t isquit eprobabl etha t inth e lastpolde r tob emade ,agricultur ewil l form themai nactivity . Intha tcas ew e canunde ragai nne w circumstances,wit hne w techniques perhaps,bu twit hol d experience,continu e thiswor ktha tstarte d over 1000year sago .

- 174 POLDER MANAGEMENT INTH E NETHERLANDS THEMANAGEMEN TO FPOLDER S INTH ENETHERLAND S Drs.J.H.M .Kienhui s Unieva nWaterschappe n (Uniono fWaterboard s or TheWaterboar d Association) TheHague ,Th eNetherland s

1 Introduction

Thetitl e ofm ypape r could perhaps giveth eimpressio n thatpolder s inth eNetherland s have adifferen t typeo fmanagemen t to theres t ofth ecountry . Ina certai n sense this istru e forth ene wIJsselmeer - polders, forexampl e theFlevopolder .Fo r the initial functioning ofth epolders ,durin g the construction and commissioningperiods , there isi nfac ta managemen t organization which differs from the generalpattern .W e dono t intend total kabou t thisrathe rshort - term type ofmanagemen t today,bu trathe r aboutth emanagemen t system which hasoperate d for centuries inexistin gpolders .I nthes epol ­ dersth e system ofmanagemen t isprincipall y similar totha tfoun d generally throughout thecountry .Wh y thend ow ewan t total kspeci ­ fically aboutpolde rmanagement ?Wel l iti sbecaus e thepolder ,a sa watermanagemen t identity for centuries has alsoha d amanagement / legal identity: thepolde ra swaterboard . The Institute ofWater - boards whichha sa histor y ofman y centuries in theNetherlands ,ha s notbee n limited to thepolde r alone.Thi swil l beshow n inth ere ­ mainder ofthi s introduction.Polde rmanagemen t forms atypica l exam­ ple ofthi smanagemen t system.

175 The formation ofwater-board s inth eNetherlands '

Watermanagemen t dpvelnpeda n loworpart eo fth eNetherland s during theMiddl e Ages. Inthi sth eexisting ,mainl y agrarian, localcommu ­ nities- referre d toa s "buurschappen"- playe d an importantrole . Frommonastr y records iti sknow n that,durin gth e 12th century,low - lyingarea s became increasingly subjected tosurg ean drive r flooding which, inadditio n toth etempor yfloodin gals o leadt oa mor e permanent losso f land.Thes e eventsdemonstrate d thenee d forde ­ fence ona muc h larger than local scale.Dam swer econstructe d at variousplace san d atth e sametim e drainage systemswer e constructed toremov e excesswate r from thehinterland . Around 1200an d inth e firsthal fo fth e 13thcentur y (between 1200an d 1350)regiona l water management activities increased both innumbe r and extent.I nman y districts itwa sobviou s thatextensio n and/or furtherextensio n of localdike st oprotec t larger areas,wa s essential.T oensur etha t these dams and dikesha d along-lastin g effect,maintenanc e control­ led byregulations ,wa s indispensable. Inthi swork ,clearly ,loca l communities played an important role.Th eorganizatio n ofthes e regional watermanagement s workswa sgenerall y based on cooperation between the interested communities.Dependin g onth eare a therewer e various formso fcooperatio n practiced. Generally itinvolve d aver y loosekin d ofmanagement .Thi swa sno t thecas ehoweve r for large works sucha sdam s (whethero rno t fitted with sluices). Thenmainte ­ nanceha d tob eorganize d toensur e thatth ewor k (onbot h sides)wa s coordinated. For thiswor k asupervisiona l authority wasessentia l to guarantee thatmaintenanc e wascarrie d outt oth erequire d standard. Outo fthi s cameth eregiona l waterboards,whic h developed as separate governing bodies,responsibl e forregiona l watermanagement . Astim ewen tby ,thes eregiona l waterboards gradually got ase tplac e inpubli cauthorities .

Since the 15thcentur y theyhav ehad , inadditio n toa representative body,a boar d with amanagemen t and judicial identity. Inth e longrun ,thi sboar d became the supreme,als o legislative, organ ofth eregiona l waterboard.

176 Inth emeantim e thingswer ehappenin g ata local level.Alread y in the 12than d 13th centuries anincreasin g numbero fcommunitie swer e constructing or extending embankments.B yth een d ofth e 12th century newso f "poires"an d "kogen"ha d spread toth edelt a inth esout h from thenort h ofNorth-Holland . Locally theseword smean tmudflat s or foreshoreo nwhic hembankment s wereconstructed . Thiswa sth e beginning, ina technical-wate r management sense ofpolder s inDutc h history. Inth e 13than d 14thcenturie s datao npolderin gbecam emor e widespread. Slowly butsurel y atvariou splace s along the coastan d the largerriver s thehabitabl e areaswer e extended.Thi sproces so f poldering and land-winning continues today.Polde r construction has notbee n limited toonl y thecoast ,estuarie san d largerrivers .A t the end ofth e 13thcentur y thisproces swa sals ouse d inth e hinterland whereth enee d becameurgen t with thebe d settlement "inklinking"whic hoccurred . Thisphenomeno n occurs inrelativel y uncompacted cultivated ground when it isdraine d bijstream san d ditches -a common situation inth elow-lyin g Netherlands.Th e settlingproces s isaccentuate d by theshrinkag ewhic hresult sfro m oxydation ofth euppe r layersuse d foragriculture . Eventually,natura l drainagewa s locally inadequate and then theonl y solutionwa st o excavate special water courses toarea swit ha lo w waterlevel. Inadditio n todrainage ,on e canals o lower theaverag e waterlevel ina smal lrive rb y damming theupstrea m section.Jus t asth ewhol e drainage situation wasbecomin gprecariou s therewa s a spectacular invention -th ewindmill .Earl y inth e 15th century the windmillwa s successfully applied todrainage .Wit h furtherimprove ­ ments inth e 16thcentur y itbecam epossibl e to drainrelativel y shal­ low lakes.Subsequen t improvements lead ultimately,unde r theinfluen ­ ceo fDutc h merchants,wh o appreciated apossibl e good investment, toth edrainag e oflarg e lakes,especiall y innorther n Holland in the 17than d 18thcenturies .

Initially, especially inth e caseso f land-winning, the supervision ofpolde rwork swa s theresponsibilit y ofth e local community.Some ­ times,especiall y withpolde r construction and the construction of

177 embankments,slice s and soo n onol d established land lying between twoo rmor e local cummunities,ther ewa son ecommuna l seto f regulations,governin g theworks .Ultimately ,th emos tgenera l legal system forpolderin gwa s thewaterboard : thepolde r inth eadministra ­ tive-legal sense;referre d tohereafte r asth e "polder".Thi swa si n addition to theregiona lwaterboard , thesecon d typeo fwaterboar d thatdevelope d inth eDutc h lowlands.Characteristicall y agrou po r "board"o fselecte d peoplewer egive n theauthorit yto : - drawu p regulations for themanagemen t andmaintenanc e dutieso f the landowners concerned; - try cases ofnegligenc e and - fixth echarge s tob epai d by the landowners:ta x assessmentsetc . Every year theboard ,a spolde r administrators,ha d toaccoun tt o a meeting oflandowner s called "devergaderin g van ingelanden". Naturally theprecis e form ofpolde rmanagemen t varied from regiont o region,whic h atthi stim ewer e strongly seperated. Therewer e differences butth ebasi c patternwa s that,outline d above.Thi s basically simplean d logicalmanagemen t system forth epolders ,ha s generally beenapplie d untilpresen ttimes .

The objecto fth epresen tpape r ist osho who w thewaterboar d system inth eNetherland s developed from local community organizations into a specific administration,responsibl e forth eneed s of localan d regional water management. Inthi spar to fth e introduction onlya n outline description canb egive n andman y interesting detailsmus t beomitted , one ofwhic hbein g the interference by the"higher " authorities with thewaterboards .Neithe r didw eg o into thematte r ofhow , inth e 19thcentur y and thebeginnin g ofth e 20th century, theprovincia l authorities introduced thewaterboard s to improve water-control for thebenefi t ofagraria nus eo fth e soil. Neither canb eexplaine d into detail thewa y inwhich ,durin g the last few decades,water-qualit y managementwa s appointed to existing regional waterboards or tonew , largewaterboard s exclusively charged with this task.Th e intention istha t thisdescriptio n willb e sufficient for agoo d understanding ofth eorigin s of the association ofDutc h waterboards inparticula r thepolde rmanagemen t system.

178 3 Thepresen tDutc h waterboard system

The attention paid by theStat e towater ,tha t isth eguaranteein g ofsafet y againstrive r and sea flooding,an d thecontro lo fwate r quality and the quantity ofsurfac ewate r forms,a s inth epast ,fo r theNetherlands ,a low-lyin g land bordering the sea,a n essential condition for lifean d survival.Withou t thecontinuin g attention ofth eStat e todam salon g thecoas tan drivers ,hal fo fou rcountr y would be flooded by the sea.Th e functioning andhabitabilit y ofthi s lowcountr y hingeso n atigh t control ofrainwate r drainage andth e waterlevel inwatercourses .Th emaintenanc e ofsurfac ewate r quality, evident especially inrecen ttimes ,i sessentia l toliving - conditions,bot h for thepopulatio n and also floraan d fauna.Th e exercising ofth eessentia l carean dattentio n is,i nou r land,th e responsibility ofth ewaterboards .

Bypubli c lawth ewaterboard , togetherwit hth emunicipalit y belongs to the lowerpubli c administrative bodyo fth e so-named thirdmana ­ gement level,tha t isth emanagemen t levelneares t tothos e actually being administered to.Th eProvinc e isth esecon d managementlevel , and finally theStat e isth e first.Th ewaterboar d canb e considered tob e afor m of functional decentralisation within theDutc hstate . Thewaterboard , asa functiona l body,canno ttak e responsibility for public administrative matters,a sdoe sth emunicipalit y -th egenera l administrative body -unles s specifically decided by law.I n principal themunicipalit y isresponsibl e for economic,cultura lan d educational affairs etc.Th ewaterboard' sresponsibilitie s are limited totask srelate d towate rmanagemen t matterswhic har e specifically stated in itsregulations .Th ewaterboar d and the municipality work incoordinatio n but themunicipalit y cannotwor k independently inthos e "areas"fo rwhic h thewaterboar d hasprim e responsibility.

The function ofth ewaterboard , asa publi c administrative body,ca n only be inth e field ofwate rmanagemen t matters.Thi sca nbe :eithe r separately or incombination :

179- - care and attention tohydrauli c structures along thecoas tan d rivers; - attention tocontro l ofwate rquantities ; - attention towate r quality and - attention toassociate droads . Inprincipa l more thanon ewaterboar d canoperat e inon e territory. For examplewate r quality control inth earea so fsevera l waterboards canb e theresponsibilit y ofon eparticula r board.Similaril y the controlo fwate r quantity,watercourse s and excess-water reservoirs canb eexercise d byon ewaterboar d forothe rwaterboard s inth ere ­ gion. These,i nturn ,coul d begenerall y responsible for thecontro l ofembankment s androads .I nothe rword s thewaterboar d system is flexible andca nb e adjusted tomee tth eneed so fth eregion .Th e provincial government is,i nth e first instance,responsibl e forth e organization andoperatio n ofth ewaterboard s init sprovince .Th e provincial government can found and dissolvewaterboards ,giv ethe m authority and also controls thecorrec t exercising ofthei rduties . The Crown,tha t ist o say,th eHea d ofStat ewit hth eministe r res­ ponsible, inthi scas e theMiniste r ofTranspor tan dPubli cWork s in turnha soveral lresponsibilit y for thewor ko f theprovince s with respect toth ewaterboards .

Itshoul d benote d that theprovince s and theStat e inadditio nt o thewaterboard s alsohav emanagemen tresponsibilitie s inth efiel d ofwate r management.Th eState ,fo rexample ,th e largewaterways , theUsselmee ran d the Zeeland and SouthHollan d channels.I ndiffe ­ rentprovince s theprovincia l governments manage thewate r quantities incertai nrivers ,fo rexample ,th eone suse d primarily fornaviga ­ tion. Incertai nprovince s theprovincia l governments haveretaine d the responsibility forwate r quality control and haveno tgive ni t over to thewaterboards . Ingenera l itca nb e said that from early times inth eNetherlands ,th eresponsibilit y for local and regional watermanagemen t hasreste d with thewaterboards ,takin g into account the facttha t iti s ideally suited for thedutie s and alsodecen ­ tralised -a characteristi c ofth eDutc h state system -represents , and has done for ages, apre-eminen t management system.

- 180 Thepresen t waterboard comprises agenera l administrativebody : representatives ofth emanagemen t "board",a genera lmanagement ,a day-to-day management and achairman ,kwow ngenerall y asa Dik e Reeve.Th e composition ofth egenera l andday-to-da y managementva ­ ries, depending onth etask san d localan dregiona l situation ofa particular waterboard. Agenera l characteristic istha tthe yar eal l composed ona functiona l basisan drepresentativ e ofth edifferen t interestgroup s directly involved inth etask so fth ewaterboard . For thehydrauli c structures,wate r quantity management androads , there aregenerall y two interested groups:th e "ongebouwd",unbuilt - group comprising ownersan d other legaluser so funbuil tpropert y and the "gebouwd",buil tgrou p comprising ownersan dothe r legal userso fdevelope d property.Thes egroup s have topa y forwate rmana ­ gement services inth efor m ofa wate rmanagemen t tax,i nproportio n tothei r interests.Th ecost s incured inwate rmanagemen tmus tb e paid by the interested parties.Th ewaterboard s haven o fixedfinan ­ cialrelationshi p with theState ,unlik e theprovincia l andmunicipa l governments.Thi sdoe sno tprevent ,however ,th eStat egivin gth e waterboards financial assistance,o noccasions ,fo rexampl e after theflood so f 1953fo r thestrengthenin g ofhydrauli c structureso n the coast and the largerivers .Th ecost s forwate r qualitymanag ­ ementar epai d onth ebasi so fth epollute rpays . Domestic/industrial polluterspa y inrelatio n toth eamoun t ofthei rpollutio n witha pollution tax.

Basic interests arecentra l towaterboar d management andg owit hth e composition ofth emanagement ,han d inhand ,wit hpaymen tan d control. It isthes e three- basi c interest,paymen t and control- which form thebasi so f the composition ofth ewaterboar d management. Iti simportan t toconside r the tasko fth eprovincia l government inthi srespect ,whic h ist oallo w thenumbe ro fseat san d their categorieswithi n acertai n waterboard. Representatives ofthes e categories are chosen eitherb y adirec to r an indirect system of election. Theai m ofth eelection s isno t tofi x therelativ e importance ofth e categories as isth ecas ewit hpolitica lelections .

181 Theproportion ,b ywhich ,fo reac h category anumbe ro fseat si s guaranteed, isfixe d inth e regulations and iti sno t true tosa y thatth ecategor y paying themost ,ha s themos t seats.I tis , however,a vali d point that,becaus eo fth eessentia l interesti n goodwate r control,o ffarmer s andmarke tgardeners ,thes e- a s ownerso fundevelope d land- hav e arigh tt oa relativel y strong representation. It isstrikin g thatunlik e theprovince san dmunicipalitie s which haveprovincial/municipa l laws,th ewaterboard s haven o directwater - board laws.Thi sca nb e explained mainly by theprimac y ofth e provincial government inth epas twit hrespec t to thewaterboard si n theprovince .Som eyear sag oparliamen t decided, on the Government proposal,tha tsuc ha la wshoul d bemad e for thewaterboards .Wit h the increasing significance inou r society ofth e responsibilities forwate rmanagemen t and thewaterboar d institute itwa s considered thatth ewaterboard s should no longer remain solely withinth e autonomous powero fth eprovincia l government.Th ewaterboar d law preparation,whic hha s involved muchhar d work,wil l ina fe wyear s consisto fth e legalrule sb ywhic h theprovincia l governmentswil l exercise their continuingprimar y responsibility for thewaterboar d system.

4 The increase in scale/concentration

Adens e network of independentpolde r administration,varyin g insiz e from tens tothousand s ofhectares ,covered ,unti lrecently ,th elow - lyingpart s ofth eNetherlands .Characteristi c ofthes e administra­ tionswa s the direct involvement ofthos ebein g administrated to, especially farmers andmarke tgardeners ,wit hth eworkin g ofth epol ­ der.A managemen t apparatus,and , infact ,a buildin gwa s generally missing.Th ewor k ofth echairma n and secretary was generallyunder ­ taken for alimite d reimbursement bijtrustyworth y people livingi n thepolder .Th epersonne l consisted mainly ofmaintenanc e workers

182 andmachin e operators fordrainag e equipment,sluice s and weirsan d alsoworker s for theexecutio n ofparticula r control and maintenance activities.Day-to-da y administration wasgenerall y carried outfro m thevillag e hall,o rsom e suchsuitabl e establishment or thehom eo f thechairma no r secretary. Some largerpolder sha d asmal lpolde r administration buildingwit hth eassociate d staff.A n important event inth epolde r administration was theperiodica l inspection tochec k ifadjacen t ownersha d carried outthei r obligatory maintenance duties.Thes e dutiescomprise d clearing plants from water coursesan d maintaining thewate rmanagemen tworks .I ncas e ofnegligenc e the polder administration was empowered toforc e theowne r responsible to carry out thenecessar y work.Alternativel y thepolde r administration could itselfcarr you tth ewor k toth ecos to fth eowner .Th e property formed -an dcontinue s to form -th e surety againstnon ­ paymento fta x andothe rcosts .

During the last 20t o 25year s small scalewaterboard s have almost completely vanished.Socia l developments have led toincrease si n scale which haveno t leftuntouche d thewaterboar d andpolde radmini ­ strationsystem .Muc h higher demands havebee nplace d onth etask s ofth ewaterboards ,especiall y by developments inagricultur e andmar ­ ketgardenin g andb y an increase inth enumbe r ofrelate d activities under theauthoritie s care inmanagement ,professional ,technica l and administrative matters.Th emanagement ,professional ,an d financial facilities ofth e existingwaterboard s could no longer copewit hth e demands created by the changing times.I nrecen tyear s thereha sbee n much discussion onwha t therespons e tothi sshoul d be.Ther ewer e those ofth eopinio n thatafte r somuc h time thewaterboar d system no longerha d arol et oplay .Other s supported new formso ffunctio ­ nalmanagement .Ther ewer eals o thosewh o thought therewa s little reason tochang e andpreferre d thepresen t system.Particularl y in poldermanagemen t thesepeopl e were attached tothei row npolde ran d werever y reluctant to letg o their own interests and joinwit h bigger associations.Ultimatel y parliament agreed,wit hon e accord, thatth ewaterboar d system should bemaintained . Thepric eo fit s

183- maintenance waspai d ina n increase inscal ean d areductio ni n number -thes e changes tob eeffecte d by theprovincia lgovernments . The former 2500larg e and smallwaterboard s haveno wbee n reduced to about250 ,rangin g insiz e from very biglarg epart so fprovince st o waterboards ofa t least10.00 0ha .Smal l scalewaterboard s andpol ­ deradministration s areno w only tob e found incertai npart so fth e country: these areshortl y tob eabsorbed .Th epolder ,i na technica l waterboard sense,ha sno tvanishe d and,a s inearlie r times,stil l requires thecontinuin g specialised attention toguarante e thewate r management interestsparticularl y ofth e farmers andmarke t gardeners within thepolder .I t isstil l important tomaintai n andeve n strengthen the involvement of thepeopl e living inth epolde rareas . There aredifferen tpossibilitie s whichmus tb econsidere d from case to case,tw omeri tattention :

- within the concentrated waterboard there canb ea certain ,mor e or lessfa rreachin g form ofdecentralisatio n into departments which havethei row n departmental administration with certain rights, for instancewit hrespec t tothei rbudget ; - election districts areselecte d andgive n certain day-to-dayadmini ­ strative responsibilities under theultimat e responsibility ofth e day-to-day management.Thes edistric t administrations togetherwit h the landowners canb e consulted onbudge tmatters ,waterboar d affairs etc;thu skeepin g alive the involvement ofth e localpeopl e withwate rmanagemen tmatters .

5 Conclusions

Inth eNetherland s because of itsphysica l origins and its location by these a- wit h adelt a and large rivers- a specia l management organization has developed over theage swhic h brings togetheran d cares for the special interests connected withwate rmanagemen t in a particular area.Th e Institute ofWaterboard s has atit ssourc e thecar e for,i.e .promotio n of,loca lan dregiona l interestsi n watermanagement . Ithas ,a s itwere ,grow n outo fth ecommunit y and

- 184 a typical outcomewa s the formation ofth epolders .T odate ,th e Institute ofWaterboard s hasbee n ablet o fulfil itsdutie s and tod o thishad ,necessarily ,undergon e arigorou s increase inscale .On eo f the fundamental characteristics ofth eInstitute : thedecentralise d promotion ofinterest swithi n the framework ofa n independent management body and inclos erelationshi p with thediffe ­ rent interested parties,ha sbee nmaintained . Althoughwate rmanag ­ ement ina technica l senseremains ,th epolder s ina nadministrative / legal sensehav egone .Perhap s "havegone "whe n looked atclosel y is toostrong . Inth eproces so fth e increase inscal e ofth ewater - boards, one tries asmuc h aspossibl e toallo w thewate r management "unity"concep t- th epolde r ina technical/administrativ e sense- t o play arole .Th erecen t discussions inparliamen t have indicated that iti sfull y appreciated that,particularl y inrelatio n to thevariou s interests involved,th ewaterboard smus tb eadministere d effectively. Polders arepre-eminentl y ofessentia l significance tolif e andli ­ ving inth eNetherland s lowlands.Th ewa y thatsociet y has developed has had astron g influence on thefunctionin g ofth ewaterboar d system especially ofth epolders .I nspit eo frecen t changes,th e pre-requisite thatregiona l and local interests arebrough t together toachiev e responsible watermanagement ,continue san d thisunde r the auspices ofa specific ,caring ,administrativ e organization.

1)Thi sparagrap h has for alarg epar tbee n abstracted from apubli ­ cationo fProfesso r H.va n derLinden ,Hea d ofth eAncien tHistor y LawDepartmen t ofth eFre eUniversit y ofAmsterda m andDik e Reeve ofth e "Groot-Waterschap" ofWoerden .

185- 186 ECONOMICASPECT S OF SOIL CONSERVATION PROGRAMS INLDC s Alfredo Sfeir-Younis TheWorl d Bank,Washingto nDC ,U.S.A .

Abstract

This paper isabou t theeconomi c aspectso f soilconservation . Iti s wellknow n thatmillion s ofhectare s are being irreversibly lostfo r agricultural production or for other economic activities. FAOha s esti­ mated thathistorica l soil lossesamoun t to 2billio n ha and that 5-7 million ha are being completely lost every year through soildegrada ­ tion. Theeconomi cevaluatio n of soil conservationproject s seemt o pose some difficulties both to thenatura l scientist and theeconomist . Tofin d a common ground between thoseproblem s related to thenatura l environment and economic decision system, thepape r isoutline d ina self-contained way. After describing,ver y succinctly, thecharacteris ­ tics of soilerosion ,som e of the salient economic aspects of soilcon ­ servation are defined. Thepape r also describes a fewapproache s for the economic appraisal of this type ofprojec t and reviews several case studieswithi n thiscontext . Thefina lsection s dealwit hproblem s in implementing this typeo f program in thedevelopin g countries andwit h themos t salient policyissues .

1 Introduction 1.1 SomeHightlight s

Despite the fact that soil ison e of themos t important natural resources indevelopin g countries,n o statistics are available onth e

187 precise extent of soilerosio n damages around theworld . However,i ti s wellknow n thatmillion s ofhectare s are being irreversibly lostfo r agricultural production or for other economic activities. FAOha s esti­ mated thathistorica l soil losses amount to 2billio n hectares and that 5-7millio nhectare s are being completely lost everyyea r throughsoi l degradation. This isa phenomeno nwhic h affects both developed aswel l as developing nations. For example,losse s ofproductiv e topsoils in theUnite d States amount to7. 4 tonspe rh ape ryear . Similary,tota l area affected inAfric a addsu p to35 %an d inth eNea rEas t up tonearl y 61%. Countries densely populated and highly dependent on agricultural production,lik e Indiaan dNepal ,hav e severalmillion s ofhectare s affected bywate r and soil erosion,salinit y and floods. InIndia , 90millio nh aar e affected bywate r erosion,9 0millio n ha bywin d erosion,7 millio nh ab y salinity and 20millio nh ab yflooding . In Nepal,i tha sbee nestimate d thatnearl y 8.5millio n ft^o f soilar e lostannually ;thes ear etranslate d intoproductivit y losses of 1%pe r year ora nequivalen t ofUS$1 0millio n per year. Inmiddle-incom e countries,lik eArgentina ,thi s isals oa critical problem: 13%o f the land isaffecte d bywate r erosion and 16%b ywin d erosion [4, 15].

To bring landsbac k tothei r productive capacity requires inman ycase s sizable amounts of investments. Few countries have systematically dealt with this issuedu e to thenatur e of theproble m (social and institu­ tional)an d thetype s of investment needed. Inman y developingcoun ­ tries, th earea s which are going throughheav y soildamage s coincide with areas ofhig h population density,particularl y of low-income groups. Because these people arepoor ,thei r need toexploi t thelan d toit slimits—i n most cases toproduc e onlya subsistence crops—poses a serious environmental threat toman y areas of theworld . Inaddition , investment packages for these soil conservation programs areusuall y expensive,an d their potential benefits areexpecte d tocom e far inth e future (this isparticularl y truewhe n land reclamation takes place). Also,wit h oftenunstabl e political systems,decisio nmaker s aremostl y concernedwit h investment decisions ofhig hvisibilit y (e.g.,larg e infrastructures,tunnels ,reservoirs )o r of quick returns. Thesear e not characteristics of soil conservation programs. Inth e final analysis,on e findsman yLDC s sufferingfro mseriou s environmental deg­ radation butwher ever y little isdon e toalleviat e theproblem .

The paper focuses onth eeconomic s of soil conservationprograms . Because of thenatur e of theproble m addressed here,an d theaudienc e forwhic h thepape r is intended, the approach followed isbelieve d to keep the subject relatively comprehensive forbot h thenatura l scientist and theeconomist . Before getting into themai n topic,th eremainde r of this sectionwil loutlin e verybriefl y thenatur e and roleo f theWorl d Bank.

Although theconferenc e focuses onpolder s around theworld , this paper does not specifically address theengineerin g aspects or allpossibl e economic aspects ofpolders . Several reasons account for this: first, theBank' s lendingprogra mha s only afe wpolde r projects,mos t ofwhic h were designed todea lmor ewit h soilerosio n and conservation thanwit h land reclamation. And second,i twa s thought useful to focus onth e analytic framework for theevaluatio n ofproject s affecting soil qual­ ity;thi s applies tobot h polders and other projects (e.g.,irrigation , forestry,agricultura l development). Sections 5.1 and 5.2mak e specific reference topolders. 1

1.2 TheWorl dBan k

TheWorl d Bank is the largest provider of loans foragricultura l devel­ opment in thedevelopin g countries of theworld . Over thepas t five years,1977-81 ,th eBan kha scommitte d more than $17billio n for agri­ cultural development;thi s investment has elicited $2billio n inco - financing and $20billio n from local sources ora tota lo f $39billion . This isa ver y substantial sumindeed ,bu t most experts on the subject agree that total investment inagricultur e falls considerably below the requirements for thesustaine d long-term increases inproductio n that will beneede d over thenex t 20year s orso .

TheWorl dBan k isa nintergovernmenta l lendingagenc y that isowne d by its 134membe r countries. TheBan k isgoverne d by itsExecutiv e

189- Directorswhos e votes areweighte d by their contributions to theBank' s capital stock. The largest stockholder isth eUnite d States,followe d by theUnite d Kingdom,Germany ,France ,an d Japan. TheBan k isa multi ­ national institution,an d itha sa multinationa l staff drawn fromal l itsmembe r countries. The overall task ist oprovid e technicalan d financial resources tostimulat e soundly based economic growth primarily through project lending tomembe r countries. No less important isou r commitment toprotec t theresource s entrusted by the countrieswh o subscribe capital and by thosewh o buy IBRDbonds . To this end,Ban k projectsmus t be financiallyviable ,technicall y feasible,manageriall y sound,an dyiel d arat e of return at least equal toaverag e returns from other investment in theborrowin g country.

TheBank' s organization and structure hasevolve d since itwa sestab ­ lished immediately afterWorl dWa r II. Itno w includes three distinct legal entities (IBRD,IDA , IFC), eachwit h separate assets,liabilitie s and capitalization.

1.2.1 The International Bank forReconstructio n and Development (IBRD)

This entityuse s theequit yentruste d to itb ymembe r governmentsan d earnings retained from 35year s ofprofit s toborro w in theworl d capi­ talmarket s and reiend todevelopin g countries. Loan terms arerepay ­ ment over 18years ,a 5-yeargrac e period,an d interest rates reflecting the fullcos t ofou rborrowing s and administration ata curren t rateo f 11.6%. This isabou t 40%les s than theaverag e cost of recent borrow­ ings inth eU.S .an dEurocurrenc ymarket s bydevelopin g countries such asBrazil . IBRDbond s are ratedAA Aan d arehel d by investors inove r 90countries . Init s 30-year history therehav e beenn odefaults . It has recently beenagree d that theBan kwoul d double its capital from US$40billio n toUS$8 0billion . There areno w 134membe r countrieso f theIBR Dan d current annual commitments areabou t $9billion .

190- 1.2.2 The International Development Association (IDA)

IDAwa s created in 1960whe n itbecam e apparent that the cost ofservic ­ ing external debtswa s becoming unmanageable by thepoores t countries. IDAwa s thereforese tu p torecycl e fundsfro m richer member countries, includingBrazil ,an d IBRDprofits . Project credits from IDAar e pro­ vided only topoore r countries,primaril y inAfric a andAsia ,wher e the GNPpe r capita is less thanUS$32 0 (1977prices) . Lending termso f these credits arenoncommercia lwit ha repayment period ofu p to5 0 years,n o interest charges,an d aservic e charge of 0.75%pe r annum. The IBRDan d IDAar eadministere d by the same personnel,an d projects meet thesam e criteria. IDAha s 121members . Commitments arerunnin g ata curren t annual rate ofabou t $3.5billion .

1.2.3 The InternationalFinanc eCorporatio n (IFC)

IFCwa s created in 1956t ofoste r thegrowt h of theprivat e sector equity financing indevelopin g countries. IFCobtain s funds largely frommembe r country subscriptions and theIBR Ditself . Itha s 109 members. The IFCcollaborate swit h theprivat e sector indirectin g resources,bot h domestic and foreign,int o productive investment in member countries. Itorganize d $3,340millio nwort h of capital forLD C enterprises inFY198 1 inadditio n toothe r important activities develop­ ing thedomesti c financial markets of thosecountries .

Iti simportan t toemphasiz e that theBank' s charter calls for loans to bemad e on thebasi s of economic criteria. The emphasis oneconomic si s essential,becaus e theBank' smember s include countries witha wid e range of political spectra: centralmarke t economies aswel l ascoun ­ trieswit h freemarke t economies. Most of our poorer andmor e populous member countries,though ,ar e inth e tropics—a factorwhic hha s special significance inagricultura l development.

191 1.2.4 TheBasi cApproac h

The rest of thepape r isdivide d into the following sections: - characteristics of soilerosio n - economic aspects of soilconservatio n - approaches for economic appraisal - case studies implementation problems - private sector and fiscalimpacts ;an d policyissues .

Themeri t inwritin ga short paper liesmor e in the synthesis of issues it requires than onth earra y ofanswer s it provides. The literature is diverse and focuses ona countless seto f technical,economic ,institu ­ tional, socialan d cultural issues. A substantial portion of the eco­ nomic literature has beendevote d totes t behavioral relationships with the aim toasses s thebeneficia l impacts of soil conservationpractices . Variables sucha s security of land tenure,far m size,intensit y incro p production,replacemen t or substitution among crops,an d increases in theus e of inputs aresom eo f them. Inaddition ,som e economists have attempted toasses s theimpact s of suchpolicie s as taxes,subsidies , changes inlan d use patterns and other regulations onsoi l conservation practices,mostl y inth e context of developed countries. Finally,a n important part of the literature dealswit h theplannin g process,par ­ ticularly with regard to land classificationan d land use policieso f whichver y little issai dhere .

Theexample s used toillustrat e someo f the issues areno tgeneraliz - able. One could easily find counter-examples,whic h oftenexis t because of thenatur e of theproblem .

Long-term environmental considerations and the corresponding decision­ making process involve plenty ofvalu e judgments. Intergenerational and interpersonal equity issues,compensatio n ofpotentia l losers(e.g. , programs which require postponement inproduction) ,choic e ofdiscoun t rates,an d choices of shadowprices ,al l involve valuejudgment swhic h relate more topolitica l and institutional choices than toeconomics .

192 2 Characteristics ofSoi lErosion 2 2.1 Types of SoilErosio n

Soilerosio n isa proces swhic husuall y includes twodifferen tsteps : the removal of soilparticle s and the transportation of them tosom e place inth e system. Several types of soil erosion have beendistin ­ guished,dependin g on theagen t that causes the removal and transport. Themos twidel y known arewate r andwin d erosion. Whenwate r provokes theunifor m removal of athi n layer of soil,i t isusuall y identified as sheet erosion. Incontras t toshee t erosion,whe n detachment and trans­ port result fromsignifican t masses ofwate r supply,i t isusuall y iden­ tified aschanne l erosion (i.e.,ril lerosion ,gull y erosion). Stream- bank erosion isa for mo f channelerosion ,an d itma yoccu r onth efarm , within an irrigation distribution systemo r in rivers. Inwate r ero­ sion,detachmen t of soilsusuall y occurs due to rainfall [8,9] ,excep t instreamban k erosionwher e channel flowsprovid e largeamount so f detaching energy. The transportation ofparticle s ismostl y afunctio n ofrunoff—th e difference between total rainfall and theamoun t that can possibly be stored. Infiltration rates (amount ofwate r entering into thesoil )an d percolation rates (downward movement ofwater )wil l greatly affect therunof frates .

Other forms of soildegradatio n should also bementioned : desertifica­ tionan d salinity.

Several factors significantly affect soil erosion. Themos t important are: uncontrolled deforestation,unsatisfie d wood fuelenerg ydemands , certain forms of intensive agriculture,imprope r agriculturalpractices , shifting cultivation,overgrazing , fires,demographi c and regionalfac ­ tors. Denuded soils left asa result of those activities area tgrea t risk.

The amount oferosio n produced by those activities depend on several factors: soilpropertie s (e.g.,permeability , texture,structure) , natural vegetation (e.g.,type ,extent) ,rainfal l patterns (e.g.,dis ­ tribution,amount) , slope ofsoils ,an d cultural practices. There are also some socioeconomic (e.g.,hig hpopulatio n density,poverty) ,

193- political,an d institutional factors (e.g.,lan d tenure,siz e ofth e farm)whic h affect soilerosio n rates. These factors are present both indevelope d and developing countries. For example,a stud y inth e U.S.A. [10]conclude d that "therelationshi p between net farm incomean d mean levelso ferosio n appeared todepen d onth e tenure category ofth e landowners ...ful lowne r operated ...wer e associated with lower rates of erosion" (p.1073) .

2.2 SoilErosio nEffect s

Several types ofnegativ e effectswil l appearwhe n soil conservation practices areno t followed,e.g. ,lan d going out of production,defi ­ ciency innutrien t levels of existing lands,an d human and physical capital deterioration. Itma yb e convenient toclassif y soilerosio n effects into threemai n categories: (a)intrafar meffects ,e.g. ,los s in fertility,decreas e inare a cropped,decreas e incultivatio n inten­ sity; (b)interfar meffects ,e.g. , silt,sedimentation ,increas e or decrease inwate r runoff,decreas e inth eproductivit y of groundwater supplies;an d (c)interare ao rdownstrea m effects,e.g. , sedimentation of river basins,siltatio n of reservoirs (decrease ineconomi c lifeo f projects),cloggin g ofirrigatio n canals (decreasing operation effi­ ciency),an d increases inth eprobabilit y of flooding. While thefinan ­ cialanalysi s should beabl e tosho w if there isenoug h incentive toth e individual farmers for investing insoi l conservation programs,th e eco­ nomic analysis should shed some light in assessing theimpact s ofexter ­ nalities,i.e. ,interfar m and downstream effects (the fiscal impactwil l also bever y instrumental).

Although differences between intra-an d interfarm household effects are rather arbitrary (definition of aboundary) ,thi s classificationprove s useful from aninstitutiona l and organizational viewpoint. It iscon ­ venient for identifying important benefits and costs,avoidin g double counting and assessing the institutional feasibility ofprograms .

Institutionally,whe n trying torevers e intrafarmhousehold s effects, one needs to focus ondecision s by one individual farmer;i n interfarm

- 194- household effects,on e needs todea lwit h farmers associations and their working rules (e.g.,Irrigatin g forestry);an d indownstrea meffects , one usually dealswit h the complexities ofpubli c interventions. An examplema y illustrate these complexities. Inman y cases,th eeffec ­ tiveness of soilconservatio n practices and programs (e.g.,reforesta ­ tion)depend s on theperformanc e of suchsocia l institutions astenure , the private or common property of resources or,i nothe rcircumstances , theexistin g tribalgroup s arrangements. Each of these institutional options require different treatment.3

2.3 SoilConservatio nMethod s

Toremov e oralleviat e themajo r causes of poilerosion ,policymaker s may design investment programs or institutional changes (regulation)o r both. Most investment programs include components thatma y beclassi ­ fied in twogroup s: engineering ormechanica l protection methodsan d biologicial protectionmethods . Although this classification israthe r arbitrary,i thelp s toidentif y the source ofbenefit s and costs of soil conservation projects. Among themos twell-know n engineering-related practices in soilconservation ,on e canmention : bench and channel terraces,contour-bunds ,mulching ,diversio n ditches or drains,polders , and tiered ridging.

Most of thebiological-relate d methods refer topastur e and forest plantations and management,alternativ e choice of cropping system, strip cropping,plantatio n ofwin d breaks,an d sand dune stabilization. In general,on e canclassif ydifferen t land-use groupsb y their relative efficiency of crop cover toprotec t the soil fromerosion . Aclassifi ­ cation of this naturemus t beregion -an d soil-type-specific. For example,i nregion swit h specific environmental characteristics,perma ­ nent vegetation could bemor e efficient inprotectin g existing soils than certain rowcrops . With regard tocroppin g practices,differen t forms of tillage,plantin gmethods ,fertilizer ,an d harvesting methods (e.g.,remova l ofbot h crops and roots)wil l greatly affect theproduc ­ tivity ofsoils .

195 Each of thesemethod s ora combinatio n of themwil l generate important benefits and costs tofarmers . Animportan t task fora n economist ist o quantify themonetar yvalu e of potential benefits (section4) .

3 Economics of SoilConservatio n 3.1 Concepts and Definitions

Theus e ofbenefit-cos t analysis (BCA)provide s useful information for economic decisionmaking . Planners should choose soil conservation projects which showne t present values (NPV)o f incremental benefits greater than zerowhe n discounted at theopportunit y cost ofcapital . This criterion also applieswhe n selecting mutually exclusiveprojects . Certainly,on eha s to recognize thatdecision s of this nature should includeman y other technical and institutional aspects. Inparticular , becauseo f intergenerational equity considerations forexample ,decisio n makersma ydecid e to take projectswit hnegativ eNPVs .

Soil isa natura l resource. It isa comple xresourc e becausei t includesa composit e ofman y stock and flow resources.^ Most ofth e relevant flow resources have acritica l zone of exploitation belowwhic h irreversible damagema y occur. This composite of resources isaffecte d (i.e.,consumed )b y agricultural production systems—most ofwhic h isi n demand throughplan t growth. Because of this complementarity indemand , most scientists find it convenient tomeasur e soilqualit y in termso f land productivity or cropproduction . The loss inproductivit y occurs through areductio n inroot-zon e depth,losse s inplan t nutrients (the subsoil left contains less nutrients),degradatio n of the soil structure (changes ininfiltratio n rates),an d thelike .

However,change s in theproductivit y of soils areno t necessarily corre­ latedwit h soil conservation,an d the lacko f such correlation presents, as stated next,a particula r set ofproblems . Adecreas e insoi l pro­ ductivity,du e to resource use butno t beyond the critical zone of the corresponding flow resources (e.g.,plan t nutrients),ma y be improved with theus e of economically and financially viable development programs (e.g.,purchas e and application ofnitroge n fertilizer). However,whe n

- 196- resource useha s surpassed that critical zone (e.g.,dee p gullies),a return to theorigina l oreve n anacceptabl e level ofsoi lproductivit y may beeconomicall y prohibitive (i.e.,irreversibl e process).5

Conservation of soilresource s needs tob edefine d interm s ofa n assessment of intertemporal distribution ofus e rates [3]. Conservation means or requires redistribution ofus e rates inth e directions ofth e future,whil edepletio n results froma redistribution ofus e rates in thedirectio n of thepresen t (this either results fromhuma n actions or nature). Thus,conservatio n requiresmakin g comparisons of two ormor e time distributions ofus erates .

Tomeasur e the state of conservation of soilresource s or of anyothe r composite type of resource isdifficul t since itwoul d requiremeasurin g the redistribution ofus e rates and assessing complex interactions of several stock and flowresource s (e.g.,plan t nutrients,water ,tex ­ ture). These measurements areeve nmor e complex ifon e admits that some plants or cropping patternsma y be "conserving" soilsunde r one system while "depleting"soil sunde rothers .

As stated earlier,cro p yields areusuall y used tomeasur e different types ofsoi lproductivity . However,suc ha nindicato r obscures the issue,particularl y when other exogenous factors arebelieve d tob emor e important in causing suchproductivit y changes (e.g.,weather ,increas e in inputuse )whil e disappearance of organic matters,leachin g ofplant : nutrients,an d other depleting factorsma y be takingplace .

Inaddition ,monitorin g of soilqualit y is further clouded by the accepted definition of the relationship between conservation and agri­ culture investments (i.e.,projects) . Investments areofte n identified as asourc e ofdepletio n (e.g.,increas e in livestock investments in pasture lands),whil e disinvestment (e.g.,reduce d stocking)i sbelieve d to lead toward conservation. This isno t always the case. This paper mainly focuses oninvestment s and actions thatwil lhopefull y change the distribution ofus e rates toward the future or thatwoul d avoid irrever­ sible situations. The analysis of physical investments ortechnologies ,

- 197 however,i s incomplete ormeaningles s without focusing on thearra yo f institutions that gowit h them.

A specific examplema y illustrate this point. Stevens [15],usin g the case ofNepal ,define s the "critical zone"a s thepoin t beyond which nutrients become unavailable toplan t growth (for land cropped year after yearwithou t applying fertilizers). Beyond this point itbecome s uneconomical for farmers torecuperat e theland . The criticalzon e varies depending onth e environmental characteristics of soils. As noted inFigur e 1 [15],tw odimension s of theproble m areused : - three levels ofproductivit y (i.e.,permanen t production, threshold line,an d permanent impairment),an d time (in years).

Permanent ProductionLin e

^e/ta4

Figure 1.Tim e period fora give n land area toexcee d the threshold with agive n technique

As referred toi na sectio n later on,redistributio n ofus e rates— toward thepresen t or future—may also result from changes ininstitu ­ tional arrangements (i.e.,lan d tenure,taxes ,subsidies) ,wit hinvest ­ ment being held constant. Consequently,soi l conservation programs and policies need tob emeaningfu l and easy togras p bypolicymakers ;other ­ wise,a largeportio n of our effortwil l belost .

- 198 3.2 Conservation Decisions [2]

Since therear eman y causes thatmigh t redistribute use rates of soils toward soil depletion,conservatio n decisions are complex. Individual farmhousehold s are thedecision-makin g unit at themicr o level. Using a rather simple framework fordescribin g farmers'soi l conservation decisions,on ema yassum e that suchdecision s depend onincome ,institu ­ tions,an d theplannin g horizon. For example,low-incom e farmerswoul d be lesswillin g topostpon e consumption—and release thepressur e on intensively cultivating landswhic h are quickly eroding—thanhigher - income farmers.

Several types of imbalances—biological,technological ,suppl yan d demand (for inputs and outputs),privat e versus social costs,socia l time preference and institutional—cause changes infarmers 'behavior . Several farming systems showsom e of these imbalances: shiftingculti ­ vation,rang e burning,lac ko f fire protection,overgrazing ,an duncon ­ trolled tree cutting,al lo fwhic h become depleting factors of the basic soil-carrying capacities. Inaddition ,suc heconomi c and institutional variables asprice s (infavo r of "crop depleting" practices),invest ­ ments,uncertaint y inlan d tenure,to o small farmsize s (makingi t uneconomic toadop t soil conservation programs),lac k of public services (e.g.,extension ,research )an d input supply of several flowresource s (e.g.,fertilizers) ,structur e of taxation,incom e levels,an d farmers personal timepreference s (thenee d toconsumer s today,e.g. , fuelwood), all affect farmers behavior.

3.3 EconomicCharacteristic s ofSoi l Conservation Programs [7]

Is there any characteristic thatmake s soil conservation programs unique when compared toothe r projects? With theexceptio n of afew ,th eus e of benefit-cost analysis (BCA)i sa s easy or complicated as inan y other project. This section first highlights themos t salient economic aspects of soil conservation projects and,second ,outline s alternative appraisal frameworks.

- 199 There are several characteristics thatmak e soil conservation projects rather unique. First,soi l conservation programs aremultiproduc t in nature. Namely,beside s their impacts on theecolog y of soils,thes e programs produce several other joint products (e.g.,forestr y programs produce fuelwood,timber ,fruits ,woo d poles,fodder ,wate r catchment protection,floo d control,shade) . Thenatur e and structure of the demand,a s itaffect s relative prices across products,wil l affect the extent towhic ha progra m iseffectiv e in the conservation ofsoils .

Second,assignmen t ofmonetar y value tosom eo f theexpecte d benefits and costsma yb e difficult. This isparticularl y true for environmental effects. Valuation problems are compounded by thenatur e of soilcon ­ servationmonitoring ,th e lacko fdata ,th eabsenc e of adequatemarke t signals,th e set of transaction costs,an d thelike .

Third,externalitie s arepresent . Thiswil l require focusing oncost s that areno t revealed by farmers production functions (i.e., interfarm and downstream effects). Theseexternalitie s might result from the existing tenure system—where extraction costs areno t totally absorbed by farmers,thereb y affecting thecos to fever y otheruser—th ediffer ­ ence between private and public sector risks,an d thealternativ eper ­ ceptionswit h regard touncertainty . Therefore,mos t often,lan dmarke t prices dono t reflect changes insoi lquality .

Fourth,th epresenc e of irreversibilities complicates theproces so f valuation. Thevalu e of land,equivalen t to thediscounte d value ofal l future income streams from that land,doe s not take into account the value that society assigns toeac hhectar e lost toerosion . Land seems tohav e avalu e instock . This value changes over time as afunctio no f theexistin g stock of landavailable .

Finally,intergenerationa l equity issues areinvolve d adding new com­ plexities. Soil conservation programs result sometimes inbenefit s (or costs)whic h are accrued very far in the future: by futuregenerations . The planning horizon of today's farmers may significantly differ from society's,al lo fwhic h leads toconflict s in terms of allocations and

200 use of soils. This "myopia"o f today's generation may also be consid­ ered afor m of negative externality.

Asa nexampl e of thevaluatio n problem, letu sfocu s onforestr y proj­ ects asa soi l conservation project. Only some of thejoin t products in forestry havemarke t prices (e.g.,lumber )whil e for others sometimes there isnon e (e.g.,fuelwood) . Whatever the shadowpric e used for fuelwood in theeconomi c analysis,i t should reflect not only thenee d for energy but also theexpecte d effects on soildepletion . To comeu p withusefu l estimates of fuelwood prices,on eneed s tostud y rural marketsmuc hmore ,appl y newmethod s fordeterminin gwillingnes s topay , and advance theus e of proxy pricing (section A.5). Moreover,down ­ streameffect s of forests,lik e preventing siltation of reservoirs,o r interfarm effects,lik e preventing the clogging of canals (i.e., decrease inoperationa l efficiency),deman d datawhic h are seldomavail ­ able.

4 Approaches forEconomi cAppraisa l

Several benefit-cost valuation methodsma yb euse d depending onth e characteristics of future "with"an d "without" theprojec t situations. Before outlining thenatur e of eachmetho d and inorde r todefin ean d understand thenatur e of project benefits,on emus t understand therela ­ tionship between thenatura l systemunde r study and the economic deci­ sion framework.

Because the economic analysis often beginswit h anestimat e of land productivity,economist s tend toforge t that several steps havebee n followed tocomput e yields. Forexample ,on ema y need tokno who w losses intopsoi l affect farmproductivit y (e.g.,measure d incro p yields). Thiswoul d require first recognition that there isa rela ­ tionship between losses of topsoil and losses ofnutrients ,an d between losses ofnutrient s and changes inyields . TheUniversa lSoi lLos s Equation isofte nuse d toquantif y potential losses in topsoil. There isa statistical relationship between soil loss and such factors as rainfall,slope ,soi lerodibility ,cro pmanagement ,an d erosion control

201 determine the correlation between loss intopsoi l and cropyields . This isofte n estimated by correlating soildept hwit h losses in soilnitro ­ gen,an d then thosear e correlated with output. There are other formu­ lae (e.g.,soi l erosion andwin d velocity)tha tma y beuse d toillus ­ trate thispoint .

Many economists dono t grasp these ecological relationships. For them it isdifficul t toidentif y benefits other than theusua l cropproduc ­ tion (regardless ofho won eassign s values tothos e benefits). Many projects end uphavin g "marginal"economi c returns because not allth e benefits have beenaccounte d for. This also applies when identifying effects ofsoi l conservation programs;mos t projects consider only one type ofeffect ,e.g. , intrafarmeffects .

The choice ofvaluatio nmethod—a s anex t step inth eappraisa l of proj­ ects—has tob eproperl y done. Inman y instances,on emake smistake s in choosing anadequat e set ofprice s because no analysis has beendon eo n present and future "with"an d "without"projec t situations. Thisanaly ­ sis (i.e.,economist' s judgment)wil l definewhic hmethod s tob eused .

4.1 Consumer/ProducerSurplu sApproac h

Ata microeconomi c level,man y soil conservation programs have been evaluated using thismetho d under the assumption that themarke t will reflect thenatur e of theproblem . This approachuse s information provided by supply and demand functions. The absence of asoi lconser ­ vation program ("without"project )woul d shift the supply curvefo r commodities upward due toa decreas e inlan d productivity. Producers maygai n froma pric e effect. However,thi s gainma y beoutweighe d by increase inproductio n costs (land held as afixe d factor). Inth e presence ofa soil conservation program (additional costs),gain sma y result from increase inproductio n whichma yb e outweighed bya n expected decrease inprice s (supply curve shifts downwards). Onth e other hand,i nth e absence of aconservatio n program,consumer s may lose due toa decreas e insuppl y of products. However,wit ha conservation

202 program,consumer sma ygai nb ya nincreas e inth eavailabl e quantityo f products. Time asa factorwil l playa ver y important role[12] .

4.2 PropertyValu eApproac h

Two procedures need tob edistinguished : (i)marke t value and (ii)as ­ sessed value (orincom e forgone approach). Both approaches imply that land rent or land values reflect tosom e extent future income streams (i.e.,productivity )fro m the land. Soilerosio nwil l affect the quality of land,and ,thereby ,i t isexpecte d tob ereflecte d inlan d values. If landmarket s are perfect,bot happroache s should give the same results.

Themarke t value approach also applies thewillingness-to-pa y principle. Demand functions areusuall y estimated using econometric methods. The market value approach is limitatedwhe n applied inLDC s due to theim ­ perfections in thelan d markets of rural areas anddu e to the fact that land priceswil l reflect several factors other than soilproductivity : land ispurchase d also for security reasons,fo r land speculation,an d for increasing one's stock ofwealth .

In theabsenc e of amarke t value,man y projects calculate animplici t value of land bydeterminin g itsproductio n (e.g.,alternativ e cropping patterns)capacit y "with"an d "without"th eprojec t (net benefits being defined by thedifferenc e between the two). Thisvalu e only reflects our estimate of land floweffects ,an d therefore cropproductio n esti­ mateswil l tend tounderestimat e land values. In the traditionalBCA , no stock effects are accounted for inassessin g theopportunit y costo f land. The presence of soil erosion and the real risk of irreversible damagewil l also affect the stockvalu e of land.°

The land value approach operates under ase t of specificassumptions , not allo fwhic h arerealisti c in the context of developing countries. First,i tassume s that changes inth e quality of land isvisibl e by consumers,and ,therefore ,th epric e of landwil l change ina continuum with changes inlan d quality. This continuum does not always exist

- 203- either,becaus e people inLDC s are attached to the land and fewtrans ­ actions takeplac e or because quality isno ta dominant factor inth e process of land prices formation. Another factorwhic h limits the extent towhic h land prices reflect changes inqualit y is theexcessiv e segmentation of rural landmarkets .

4.3 Replacement ValueApproac h

Soilerosio n results indownstrea m effects usually captured by changes in theeconomi c life,fo r example,o f irrigation infrastructure,ground ­ water development,o rothe r economic activities likeagricultur e and fisheries (these important social costs need tob e considered). Silta- tiono f reservoirs reduces their economic life,dependin g upon the existing siltation rate. Soil conservation programswil l decrease such siltation rate,expandin g theusefu l lifeo f infrastructures. Ifn o program isadopte d (future "without"th e project),th eeconom ywil l have to replace suchinfrastructur e (i.e.,shado wproject )soone r than expected. The cost ofreplacemen t could beuse d toestimat e potential benefits (i.e,"cos t saving benefits"). By the same token,replacemen t of tubewells ordifferentia l pumping costs could be accounted fora s benefits of soil conservation projectswhic hwoul d prevent furtherdete ­ rioration of existing aquifers. This approachma y also beuse dwhe n changes in theeconomi c life ofsoil s is appraised.

4.4 TravelCos tApproac h toRecreationa lBenefi t

In some cases soil erosion affects recreational facilities through decreasing the fishing productivity of lakes and reservoirs,increasin g turbidity inwaters ,creatin g fetid odors inwater suse d forrecrea ­ tionalpurposes ,an d others. Recreational benefitsma y bemeasure d by estimating consumers'willingnes s topa y revealed byexpenditure s asso­ ciatedwit h travel time and distance. Since this doesno t seem topla y a major role inrura l areas,n o further analysis isgiven .

- 204 4.5 OtherApproache s and ProxyValue s

First,estimatio n of socialdeman d curves has beenprove nusefu lwhe n one isabl e toidentif y howmuc h society iswillin g topa y toavoi d violating asaf eminimu m standard of soilconservation . This approach hasbee nuse d inth eBan k toevaluat e nutrition interventionprograms . Second,th eus eo f socialaccountin g matrices may proveusefu lwhe non e tries toallocat e benefits and costs and their incidence. TheBan kha s used this approach insecto rwork . Finally,prox yvalu ema y beuse dt o estimate theimplici t price of commoditieswhos emarket s dono t reveal prices.

An example inth eus e ofprox ymethod s is thevaluatio n of fuelwood.' Themos t frequently used proxymethod—directl y linked tosoi lconserva ­ tion decisions—is todetermin ewha t type ofproduct s that affect soil productivity at themargi nwil l substitute for fuelwood asa nenerg y source. Inrura lareas ,lac ko f fuelwood is satisfied byburnin g cow dung or crop residues. Inparticular ,Ban kproject s haveuse d the value of cropproductivit y that society loses by substituting fuelwood for cowdun g (oragricultur e residues)whe n fuelwood isno tavailable . The implicit assumption here is that elasticities of substitution between fuelwood and cowdun g arehigh ,whil e thepric e elasticities of substitution of fuelwoodwit h regard toothe r sources of energyi s assumed tob ever y lowo rzero. "

Thisprox ymetho d cannot beuse d indiscriminately, since toadvocat e such substitution,on ewoul d require athoroug h analysis of thesuppl y and demand structure forenerg y "with"an d "without" theproject . In some projectsw ehav eassume d that all these cross-partial price elas­ ticities are zero ("one must supply only fuelwood"),whil e in othersw e have assumed that these elasticities arehig hwit h respect tosevera l other alternative sources of energy (i.e.coal ,kerosine) . The basic task here is todetermin e theopportunit y cost of fuelwood soa sno t toover -o runderestimat e aproject' sbenefits .

205- 5 ProleetAppraisal : FewCas eStudie s 5.1 EconomicEvaluatio n ofPolder s

Untilnow ,thi s paperha sno t focused mucho npolders . Most WorldBank - financed polder projects reviewed for this paperwer e designed tocon ­ trol streambankerosio n and topreven t floods. Only oneBank-finance d project froma sampl e of several projects considers the constructiono f a polder like theone s inth eNetherlands ,namely ,wher e land is actually reclaimed from thesea .

The construction ofpolder s isassume d tohav e several importantbene ­ fits besides thosebenefit s stemming from land reclamation. Intrafarm effects include theincreas e inlan d productivity byenablin g the land, subject tofloods ,t ob ecultivate d during thewhol e cropping yearan d by controlling salinity. Interfarmeffect s include land reclamation and thecontro l of streambank orriverban k erosionwithi n theprojec t area. Downstream effects include prevention of flood damages (e.g., land,houses ,capita l stock),siltatio n of reservoirs,an d decrease in the productivity ofothe r rural sector activities (e.g.,freshwate r fisheries).

Themos t important external effect introduced by the construction of polders is the change in theproductivit y of existing freshwater fish­ eries. Polders and embankments tocontro l floods and streambank erosion would change thehabitat' s quality of fishgrowt h through changes in salinity,wate r temperature,an d spawning habits. These rather negative effects havebee navoide d byprovidin g thenecessar y changes inprojec t design (e.g.,fis h ladders)o rb y financing fishhatcherie s (i.e.,th e "shadow project"). If such investments areno t provided, important losses inincom ewoul d occur through both fishproductio n (i.e.,fisher ­ men's catchwil l decline)an d animal protein consumption.

5.1.1 Yong SanGan g IIProjec t

The project is thesecon d stage ofa pla n for irrigation,drainage ,an d land development inth e lower reaches of theYon g SanGan gRiver . The

206 project isdesigne d tobenefi t 20,700h a through irrigation ofth e entire area,reclamatio n of 5,500h auncultivate d tidal flats,an d land development on 11,900ha . The project finances the construction ofa n estuary dam across themout h of theYon g SanGang ;constructio n ofa 4,000m long sea polder;constructio n of irrigation facilities;recla ­ mation of tidal land development and consolidation;projec t building, access roads and atemporar y pier;an d connectingservices .

The polder,extendin g downstream of theestuar y dam along the left bank of theriver ,woul d be constructed toreclai m 830h ao f tidalflats . The polderwil l be4,00 0m long and about 8m high. The body ofth e polderwoul d be compacted earthwit ha roc k zone on the seaward face. A sluicewoul d be constructed at thedownstrea m end of thepolde rt o permit drainage of the reclaimed areaa t lowtides .

The totalprojec t costwa s estimated atUS$167. 0million ,wher e the polderwoul d costUS$2. 0millio n and the sluice gatesUS$10. 7million .

Themajo r beneficial environmental effect would be to improvewate r quality in thelowe r reaches througheliminatio n of seawater intrusion. Two downstream effects could beexpected : sedimentation inMo kP o Harbor and reduced fisheries. A survey shows that about 800household s in thevicinit y of the project engage infishin g tosupplemen t farm income,bu t nearly allo f the fishing is inshallo w coastalwaters . Therefore,constructio n isexpecte d tohav en o significant effect on fisheries (i.e.,incom e forgone is zero). As regards effects onMo kP o Harbor,a stud y bya nexper t insedimentatio n concluded that theestuar y damwoul d not increase,an dmight ,i n fact,reduce ,th eannua l dredging requirements (about 130,000m^ )i n theharbor .

The economic benefit and justification procedures didno t include two additional downstream effects: road linkwit h other towns,an d reduced levels of salinity allowing toallocat e some of thewate r intoth e municipal areas and industries. Themai n benefits quantified inth e analysis are on-farm: land reclamation and land development. The project's overall rate of returnwoul d be13% .

207 5.2 OtherExample s 5.2.1 PhewaTa lCatchmen tManagemen t Program: ALan d ValueApproac h

ThePhew aTa l catchment islocate d InKalr aDistrict ,som e 140k mfro m Kathmandu. The catchment has anare a of 113km ^an d drainsLak ePhew a Tal. The climate ishumi d subtropical,wit h anannua l precipitationo f 3,700mm . Because of intensive agriculture and grazing in thecatch ­ ment,onl y about aquarte r of theorigina l forest remains;thi slan d isowne d by theGovernmen t ofNepal . Subsistence agriculture isth e resource baseo f thecatchmen twit h cultivation of rice,corn ,millet , wheat,potatoes ,an d other vegetables. Most familieskee p 4o r 5larg e animals forproductio n ofmanure ,milk ,an d forplowing . Forests supply fuelwood and timber forbuilding . Several resourcemanagemen t problems exist,namel ywate r supply shortages,wate r quality,erosio n problems (grazing landsbein g themos t critical), sedimentation inPhew aLake , grazing management (e.g.,numbe r of livestock,fodde r productivityo f grazing land and development alternatives—keep animals off—and legal jurisdiction),an d forest and agriculturalmanagemen t (culturalprac ­ tices,nutrien t depletion). Thepropose d program includes plantation maintenance,fores t protection,pastur e establishment and protection, gully control,stal lfeeding ,an d training and technicalassistance .

The appraisal approach draws comparisons ondifferential s inpotentia l land values "without"an d "with"th epropose d programs. Values are defined byvaryin g degrees of land productivity over time,whic h is assumed tochang e depending onexpecte d output foregone. For grazing land,differen t conversion factors into animal feed and for animal feed into theproductio n ofmil k and fertilizer (net of production and other costs)wer e estimated. The fertilizer andmil kvalue s of the grasswer e estimated atNR s 11/ha/yran d 72/ha/yr,respectively . For pasture land, itwa s estimated that itsproductivit y would be approximately five times that ofope n grazing land (for the same commodities). For scrub land, theanalysi s assumed that eachhectar ewoul d produce 500k g of grass, 1,500 kg of fodder leaves and 4m ^o f wood. The economic valueso f grass and fodderwer e calculated asbefor e but 96m ^o f fuelwoodwer e added. Forunmanage d forests,a productivit ywa s estimated equivalent

- 208- to3,00 0k g of leaf fodder and 12m ^o f fuelwood perhectare . Finally, for plantation forestry andmanage d forests,coefficient s onfodde r and fuelwood were estimated as before. Benefits were added up and compared toth e cost of theprogram ;a B/ C= 1.7.

5.2.2 EconomicBenefit s ofShelterbelt. 9

Several benefits have been identifiedwit h theplantin g of shelterbelts or,ofte n called,windbreak . Among thebenefit s one canmention : - reducingwin d velocity and soilerosion , - modifying airan d soil temperatures, reducing evaporation and transportation, - improving distribution of snow and soilmoisture , improving distribution ofwate r insprinkle r irrigation, reducingwlndbur n andwiltin g of cropplants , - protecing newly needed crops fromblowout ,an d - protecting mature crops from lodging. Interm s of specificeconomi c benefits,dependin g oncircumstances ,on e may account reduction inenerg y requirement,buildin gmaintenance , reducing mortality in livestock,improvin g theproductio n and qualityo f crops and fodder,controllin g soilerosion ,providin g shade,an d many others [1,16 ,17] .

TheBan k tried toestimat e theeffect s of shelterbelts on landproduc ­ tivity;i tha sbee nestimate d that for certain crops thepresenc eo f shelterbelts would double existing productivity. These data comefro m experiments and several studies around theworld . InNige r [13],i twa s estimated that yields ofmille t would progressively increasewit hth e height of thewindbrea k up toa certainpoin t; th eaverag e increase in yieldswa s found tob e 29%. TheNige r report concluded furthermore that asa result from shelterbeltswin d erosion is reduced considerably and soilmoistur e andyiel dwer ehighe r than those crops left in theopen . In theU.S . [17],a functiona l relationship has been estimated between distance from the shelterbelt andyield s (as apercentag e ofnorma l yields). It is shown that between 1.3m and 12m ,yiel dwoul d beabov e

209 thenorm ;th ehighes t yield (over 50%)i s reachedwit h ashelterbel t of 5m .

5.2.3 IndonesiaWatershe d ProjectAppraisa l ofDownstrea mEffec t

TheBan kha s done some crude calculations for appraising the economic value of reducing soilerosio n and siltation of streams. Here,onl y down stream effects havebee n clearly singled out. Itwa s estimated that only 50%o f allth e siltwhic h enters the riverbasin would cause quantifiable damage downstream; this includes siltation of dams,canals , fishponds,ports ,floodways ,an d other structures. The study assumes that damage costs area t least aslarg e as theeconomi c cost of removal or alleviation (replacement costs). Impacts on theeconomi c lifeo f reservoirs and other structureswer e also studied.

5.2.4 Tunisia-Northwest RuralDevelopment : Intra-an d InterfarmHousehol d Effects

Thisprojec t recommended financing a4-yea r time slice of a 15-year development programfo r 311,000h ao fTunisia' s 1.46millio n haNorth ­ westRegion . Project actionswil l beundertake n on 162,000h awithi n the area subject to soilerosio n or susceptible to crop production in­ creases. Theprojec t areawa s divided into2,00 0h amicrozone s distin­ guished by types of land ownership and use,an d by topographicalan d agriculture characteristics. Theprojec t components include - measures todecreas e soilerosion , - agricultural development, - forestry production, - livestock development, - production infrastructure (e.g.,roads) , - social infrastructure,an d - technical assistance.

- 210 The soilerosio n production program includes changes in cultivation practices (contour farming,continou s cropping ofcultivabl e land, introduction ofdifferen t crops onalternativ e parcels downhillside s toreduc ewate r runoff);contou r banking systems and planting ormain ­ tenance of permanent pastures,an d planting of forest inarea swher e cultivation must be stopped and conditions dono t permit pastures to prevent erosion;an d fencing off,supervise d grazing,wate r control works,an d afforestationo n land surrounding gullies and riverbeds (overgrazing andwate r runoffs causing the erosion).

Most benefits and costswer e appraised as theactivit y affects cropan d livestock production. Changes in cropproductio n tosom e superior crops,increas e inmil k production,fuelwoo d and forest products,over ­ all increase inyield s of food crops,an d beef products. After includ­ ing all costs,a financia l analsyiswa s carried out tose e theexten t towhic h farmersha d any incentive toparticipat e (other things being equal). The financial rates of return tofar mmodel s fluctuated between 22%an d 62%. Such returnswer e notpositivel y correlatedwit h farm size. However,i twa s found,a s onewoul d expect,tha t the project's rateo f returnwa spositivel y correlatedwit h theplannin g horizon or the time slice,achievin g anoptimu mwhe n considering aprogra m of1 5 years (i.e.,ER R= 16%) .

5.2.5 Ethiopia -Wolam oAgricultura l Development: IntrafarmHousehol dApproac h

Inthi sproject ,soi l conservation measures include bunding and contour cultivation,gull y control and land rehabilitation,wate rdevelopment , and programmonitoring . Twoelement swer e defined inorde r to carry out the economic analysis: (a)a ne t value of production figureB r 150pe r haan d (b)a decreas e insoi lproductivit y in theabsenc e of this proj­ ect and a5 %dro p inproduction . Under these assumptions,th e economic rateo f returnwa s estimated at 11%. No attemptwa smad e toquantif y benefits of gully control and land rehabilitation,thoug h their benefits were alsoexpecte d tob esignificant .

211- 5.2.6 Watershed Conservation inEcuador : EconomicLif eApproac h [6]

ThePoz aHond aWatershe d isa humid ,subtropica lwatershe d of 175km^ located 2,000k m southwest ofQuit o inth ecoasta l province ofManabi , Ecuador. Thewatershe d varies between 100-500m inelevatio n andi s steep,wit h 60%o f theare ahavin g slopes greater than 25%. Land use analysis indicates that 55%o f thewatershe d area is still innatura l forest,whil e 6%consist s of cultivated coffee and cocoa trees. Grazing land covers 22%o f thewatershe d and 3/4 of this land is subject to sheet erosion during thedr y season. Mixed farming and grazing takes place on 14%o f the land. The reservoir occupies theremainin g 3%o f thewatershed .

Theexistin g reservoir hasman y problems due tosedimentation ,t o climate,an d tointensiv e land use incertai n areas. Sedimentation sur­ veys have indicated that 20%o f theorigina l volume of thereservoi rwa s filledwit h sediment;wit h 4%pe ryea r after 5years ,on e expects the reservoir tob e filled in 25years . Inaddition ,th e reservoir suffered froma denseblue-gree n algae,causin g fetid odors inth ewater . Under these circumstances,a progra m including reforestation,constructio n of terraces onstee p and erodable land suitable for cultivation,grazin g control and rehabilitation,an d forest protection programswer e sug­ gested.

Estimation of project benefits focused ona reductio n of the sedimenta­ tion rate from4 %t o 2%. Suchreductio nwa s expected to increase the economic life of thereservoi r from 25t o 50years . The benefitswer e estimated to comemainl y from irrigation. The analysis concluded that witha longer-lif e reservoir theeconom ywoul d achieve aB/ C= 1.433, whilewit h ashorter-lif e reservoir theeconom y achieves aB/ C = .67.^ Net incremental benefits tosociet ywer e estimated atUS$30. 7million .

- 212 6 Problems inImplementin g SoilConservatio n Projects and Programs

Thoughsoun d economic and financial analysis provide useful information for decisionmaker s it isonl y one of thenecessar y conditions for the successful implementation ofsoi l conservation projects. Some of the sufficient conditions areoutline d below.

First,i twoul d be ideal that the timingo f production practices leading toward conservation coincidewit hpeople' s short termneeds . But,a si t iswel lknown ,thi s isno t thecas e everywhere. This issue isparticu ­ larly acute inarea swher e itma y beadvisabl e even tosto p production ("let thesoi lres t fora while") ; however,thi s issociall y unfeasible and,man y times,politicall y unacceptable.

Second,ther e are such considerable informationalgap s that thewhol e processma ybecom eunmanageable . Inman y instances,experiment s with soil conservation programs thatwil l provide thenecessar y information have tob e carried out togetherwit h production programs. Under these circumstances,grea t distortions occur particularlywhe n the datai s capturing changes invariable s other than those associated with changes innatura l systems (e.g.,managemen t of individual farms).

Third,monitorin g ofprojects ,i fdon e adequately isdifficul t andex ­ pensive—soil losses take alon g timebefor e one sees the realeffects . Farmers dono t opt for soil conservation program because they dono t see the immediate need for them.

Fourth,soi l conservation programs put severe stress on localinstitu ­ tions: most programs require theenforcemen t of rights,change s in farming practices,an d changes incultura l habits. These changes may bedifficul t toachieve .

Fifth,market s dono t always provide adequate signals to farmerswhe n adopting soil depletion practices. Market values of land or changes in cropyield s dono t provide the appropriate signals toreflec t losses in

213 soilqualit y and,therefore ,seldo maccoun t for the total economic cost ofproduction .

Sixth,soi l conservation practicespe rs ewil l not besufficien t to alter soilqualit y or tochang e farmers* production practices. Onema y need toadop t income policies;thes ewoul d affect therat e ofsocia l time preferences orfarmers 'biase s infavo r of crop-depletingsystems .

Seventh,a financia l and economicallyviabl e soil conservation program may need changes inlan d tenure toenabl e farmers toexpan d the sizeo f their lands. Insevera l countries this is socially or politically unacceptable.

Eighth,integratio n of soil conservation planning and implementation with development planning ingenera l isa mus t inorde r tohav eself - sustained soil conservationprograms .

Finally,ther e isa lack of appropriate administration for implementing such programs. Under thebes t of allcircumstances ,thes eprogram s are fragmented (e.g.,Ministr y ofAgriculture ,Publi cWorks ,Irrigation) .

7 Privatean d PublicSecto rFinance s 7.1 FinancialAnalysi s

Financial analysis of soil conservation is important,sinc e it isth e individual farmerwh o carries out theprojects . This presents problems inarea s of subsistence farming,sinc e soil conservation decisions are clearly affected by thenee d toachiev e subsistence first and conserva­ tion later (i.e.,lexicographi c decision making). Do farmershav e enough incentives tocarr y out soil conservation programs? Forexample , the financial analysis of suchprogram s asforestr y needs toconside r carefully: (i)competitiv euse s of land (e.g.,foodcrops )an d labor (e.g.,fo rplantin g andmaintenance) ;an d (ii)tre e species and tree plantingmode s ofmaximu m financialreturn s to farmers. Also oneshoul d consider the land tenure structure as itaffect s farmers'adoptio no f conservation practices (i.e.,lan d sizema yb e too small for farmers to

- 214- adopt these programs). Finally,financia l performance depends on,e.g. , theorganizatio n of farmers,Inpu tdeliver y systems,credi t extension.

7.2 Fiscal Impacts

The state budgetma yb eaffecte d insevera lways : compensating farmers toforg o certain benefits orprovidin g cash to farmers for implementing theprogra m (e.g.,villag e forestry schemes); - having toaffor d substantial recurrent cost expenditures since these programs demand little foreignexchange ;an d - changing the taxstructur e system. Agoo d fiscal impact statement isa necessit y ifon eexpect s any sustained success of this typeo f program. Agoo d fiscal impact statement isa necessit y if oneexpect s any sustained success of this typeo f program.

Most conservation programs require local currencies and resources. The majority ofrura l government authorities lack appropriate funds tocarr y out conservation programs. One reason for such gap is the fact that soil conservation planning isno t integrated into overall development planning.

Finally,wit h regard to taxation changes inth equalit y of landwil l correspondingly change thecapacit y topa y of this land. Consequently, governments should,i nprinciple ,ge t increasing resources as thecon ­ servation project develops. Due toinstitutiona l and otherfactors , however,thes e taxstructure s arever y rigid,thereb y not correlating (positively)wit h increases in land quality. This isa problemon e will have to livewit hit .

8 Policy Issues

Before closing,i twoul d beimportan t toidentif y somemajo r policy issues whichnee d further research.

- 215- 8.1 SoilConservatio n Planning vs.Developmen t Planning

Isolated attempts todea lwit h soil conservation areboun d to fail. The environmental sustainability of soilresources ,an d of land ingeneral , should bea central subject of anydevelopmen t plan. Given thenatur e of soil conservation programs,i t isdifficul t tose eho w this integra­ tionwoul d takeplace ,particularl y in light of tooman y development objectives.

8.2 Macro vs.Micr oVariable s

Adevelopmen t policy framework needs tob edeveloped ;thi s should take into account themacro -an d themicroeconomi c variables. With regard tomacroeconomi c variables,th emos t important is thesustaine d increase in thedeman d foragricultura l products. This expanded demandwoul d continue tobuil d substantial pressure on thedevelopmen t of bothth e extensive aswel l as the intensive margins of agricultural lands. The expansion in the supply of crop landswil l require developing themar ­ gins of agriculture. Inthi s case,i fn o coordinated policies really exist,th eris k of soil degradation israthe r great,becaus emargina l lands areofte nmor e fragile and subject tohighe r risks of soilero ­ sion.

With regard tomicroeconomi c variables,th emos t important variable to be recognized at thepolic y level is theprofi t motive of farmers. Farmerswil l bereluctan t toadop t soil conservation practices that are financially and economically unattractive. This isextremel y important in thepolic y context,sinc e tob eabl e tohav emor e programeffective ­ ness,a balanc emus t be reached between public and private investments. Neither thepubli c sectorno r theprivat e sector alonewil l be able to accomplish thepolic y objectives outlined inthi spaper .

Because the development objectives of thepubli c and private sectorma y differ,a neffor t should bemad e torecogniz e theunderlyin g behavior of each sector. This iscertainl y true for augmenting theprivat e sector's

216 adoption ofne w technologies. As stated earlier,th edevelopmen t of conservation technologies,t ob eadopte d by the farmers,shoul d be profitable.

8.3 TimeElement : IntergenerationalEquit y

Although this represents thecor e of the conservation problem,n osolu ­ tionha s been foundyet . Benefits of conservation programs areusuall y materialized far inth efuture . Theus eo f today's generation's oppor­ tunity cost and shadow prices,withi n existing discounting techniques, weighver y heavily against benefits received far inth e future. Several approaches have been suggested,e.g. ,variabl e and decreasing discount factors,n o discount atall ,us eo fvariabl e shadow prices,us eo fa n opportunity cost of land inth epresenc e of irreversibilities,change s inth eBC Aobjectiv e function,an d others. None of them are fully satisfactory.

8.4 Administration ofConservatio n Programs

Experience shows that thedegre e of successwit h soil conservation programs ishighl y correlatedwit h quality inprogra m administration. This issueha sman y facets. First,ther e isa nee d tocreat e public awareness about thesoi lerosio n problem,bot h among policymakersan d citizens. Since this awareness doesno t exist,publi c funds areno t channeled at theappropriat e rates into soil conservationprograms . Fiscal reforms areneeded .

Second,soi l conservation should be conceived as capital investment programs: investment inth e land. This seldomhappen s and,therefore , money available for those programs often come from the income savings account of thegovernmen t rather than from the capital accounts. The main implication is that funds areno t earmarked forsoi l conservation activities,an d most of themar e underfunded.

- 217 Finally,ther e Isa nincreasin g need for farmers toparticipat e and for thegovernmen t toprovid e extension services. Thegenera l idea of "soil conservation districts"i nth eU.S.A . should be considered asa plaus ­ ible system indevelopin g countries. This systemwil l enable farmers to participate more actively insoi l conservation efforts. However,a n important component isa nadequat e extension service. Unfortunately, most extension systems have focused mostly onagricultura l productivity, withver y littleemphasi s onenvironmentall y sound practices. This needs achange .

Notes

The term "polder"i suse d torefe r todifferen t things. Inman y projects,polder s areuse d as synonymfo r embankment to control streambank erosionan d reclaim land partially or totally flooded. In afe wproject s (section 5.2),th e termpolde r isuse d inth e accepted context of seasoi lreclamation . Sections 2.1-2.3ar ever ypreliminar y innature . Each typean d method needs tob eexplore d inmuc h detail thanpresente d here. Section 2relie sheavil y on [8,9 ,11] . Experience inth eBank' s financial Gujarat SocialForestr y Project has shown that reforestationprogram s inPanchaya t landshav ebee n much less thanexpecte d atappraisal . Stock resources include,fo rexample ,texture ,dept h of soilan d line zone,an d clay pans. Flow resources may beassociate d to changeable features like salinity levels,p Hlevels ,bus h and tree cover,an d rockcover . The presence of irreversibility indecisio nmakin g isanothe r specific characteristic of investment projects that affect natural environments. Shaxson [14]make s aninterestin g distinction between soil conservation (i.e.,buil d up thenutrien t capacity)an d soil reclamation (i.e.,bringin g back toit sorigina l stage thenatur eo f a stock resource component like texture). This subject needs tob e explored inmuc hmor e detail. Theimplica ­ tions are that land not onlypreserve sa valu e inus e (flow),bu ti t alsoha s awealt h instoc kvalue . This phenomenon will affect the

- 218 way inwhic h projects calculate theopportunit y cost of land. Increase inrelativ e prices ofenerg y is causing uncontrolled use of fuelwood forests inrura l areas. This process has great effect on oil erosion not onlybecaus e ofdepletio n offorest s but also because thebul k of fuelwood iscausin g losses inagricultur e production. Other important factors thatma y constrain substitution at themargi n are tastes,technology ,lac ko f roads,inefficien t distribution sys­ tems,an d prohibitive transactioncosts . Iti simportan t tonot e thather ew e are only describing increases in yield "with"th eprojec t situation. Inth eBC Ao f shelterbelts,on e needs to subtract the "without"projec t situation. 10 The difference inB/ C "with"an d "without"th e project reflects in addition toth echang e inth eeconomi c life of the reservoir,th e expected increase inlan d productivity resulting from thepropose d soil conservationpractices .

References

[1] Bogetteau-Verlinden,E .1980 .Stud y onimpac t ofwindbreak s in MajjiaValley ,Niger .Agricultura l U.,Wageningen ,Th eNetherlands . [2] Bromley,D.W . 1980.Th epolitica l economy of private resource-use decisions affecting soilproductivity .Comment s prepared forwork ­ shop on "SoilTransformatio n and Productivity." [3] Ciriacy-Wantrup,S.V . 1968.Resourc e conservation:economi c and policy,U .o f California,3r dEd . [4] FAO.1980 .Soi lan d conservation,Committe e onAgriculture , G0AG/81/8,Rome . [5] Fleming,W.M . 1980.Phew aTa l catchmentmanagemen t program,Nepal : forestry and soil andwate r conservation.Unpublishe d manuscript. [6] Fleming,W.M . 1979.Environmenta l and economic impacts ofwatershe d conservation ona MAP Sreservoir s project inEcuador . Unpublished paper.Westwate r Research Center,U .o fBritis h Columbia,Vancouver . [7] Gupta,S.B .Lai ,R .Prasad ,an dR.K .Paudey .1973 .A neconomi c evaluation of soil conservation inVaranas iDistrict ,Utta rPradesh . Indian Jour,o fAgric .Econ. ,28 ,4:205-211 .

219 [8] Hudson,N .1981 .Soi l conservation.Cornel lU .Press ,Ithaca ,NY , 2ndEd . [9] Kohnke,H. ,an dA.R .Bertrand . 1959.Soi lconservation .McGraw-Hil l Book Co.,Ne wYork . [10]Lee ,L.K . 1980.Th e impact of landownership factors on soilconser ­ vation,Amer .Jour ,o fAgric .Econ. ,pp .1070-1076 . [11]Nationa lAssociatio n ofConservatio n Districts.1980 .Soi lDegrada ­ tion:Effect s onAgricultura l Productivity.Nationa lAgricultura l LandsStudy . InterimRepor tNo .4 .Washington ,D.C. ,Oct . [12]Seitz ,W.D .e t al. 1979.Economi c impact of soil erosion.Lan d Economics,55 ,1 ,Feb . [13]Sharp ,B .an d D.W. Bromley. 1979.Soi la sa neconomi c resource. U.o fWisconsin ,Madison ,Oct . [14]Shaxson ,T.F . 1981.Lan d conservationmeasure s and related costs. FAO,Worksho p onEcon .Aspect s ofLan d Cons,unde rHumi d and Semi- Humid TropicalConditions ,Rome ,3 0June- 3July . [15]Stevens ,M.E .1978 .Lan d usepatter n formargina l land and erosion. Draftunpublishe d paper. [16]U.S .Departmen t ofAgriculture .1962 .Shelterbel t influence onGrea t Plains field environment and crops.Fores t Service Production ResearchRepor tNo .62 ,Washington ,D.C. ,Oct . [17]U.S .Departmen t ofAgriculture .1964 .Tre ewindbreak s for the Central Great Plains.Fores t ServiceAgricultura l HandbookNo .250 .

220- ENVIRONMENTALASPECT S

- J. de Jong and A.J. Wiggers.Polders andthei r environment inth eNetherland s - M. Vannuooi. Ecologicalvalue so fpotentia l polderarea s

-22 1 222 POLDERSAN DTHEI RENVIRONMEN T INTH ENETHERLAND S

J. deJon g IJsselmeerpoldersDevelopmen tAuthorit y Lelystad,Th eNetherland s A.J.Wigger s Research Institute forNatur eManagemen t Arnhem,Leersum ,Texel ,Th eNetherland s

Abstract

Theenvironmen t ofpolder s inth eNetherland s isreviewe d fromtw opoint s ofview .Th ehistorica l development of thepolde r areasdurin gman y centuries and thechange s inth enatura l environment aredescribed . Intim e thisha smean t agradua l transformationo fnatura ldr yan dwe t forests,pea tarea san d lakes inpolder suse d foragricultura l purposes with all the associated environmental losses and gains. Thereafter attention ispai d todevelopment s inth eus eo f theavailabl e space,bot ho f landan dwater ,i nth eNetherland s during the20t h century.Th e changing ofa nagricultura l society intoa nurbanize d industrial society and thedevelopment s inagricultur e itself (mechanization,artificia l fertilizers and chemical control ofpest s and diseases)hav eha d and stillhav e aprofoun d influence onth e environment inth edutc h polder regionsan dpla y arol e inth eproces s ofdecisio nmakin g about constructing and developingne wpolders .

Introduction

Inthi spaper ,whic h dealswit h polders and theirenvironmen t inth e Netherlands twomajo r aspectswil lb e reviewed. Attentionwil lb epai d toth ehistorica l development ofDutc hpolde r areasan d of theirenvironmen t and afterwards thedevelopmen t during thiscentur y inth eus eo f theavailabl e space,bot ho f land andwater ,

223- •M-,^-'. * ^'C''

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\ C I tidal flats, ti dal gullies, rivers, and lakes ?sxi-7%-v,l'| rich fresh marsh forests on eutrophic peatland tidal marshes, saltmarsh and reed marshes, locally sphagnum-, wet heather- and higher banks and levees, partly inhabited and grazed sedgevegetations on oligotrophic peatland [VUV^'-V-l complex of wet and dry forest: s on mineral soils, brackish reed marshes on eutrophic peatland k''V0l2j incl. the higher flood plains of rivers

Fig. 1.A reconstructio n of theecologica l situationo f theNetherland s inRoma n times (afterPons , 1974).

224- inth eNetherland s and itsconsequence s forpolde rarea swil lb e discussed.

Historical development

InRoma n times (thatmean s inth eNetherland s about thebeginnin go f thisera )th eecologica l situationo fth eNetherland s canb edescribe d as follows (fig.1) . On thenutrien tpoo rPleistocen e sandy soilforests ,mars h forestsan d oligotrophic peat forming vegetations couldb efound . Onth ecoasta l dunesan d islands,forest sexiste d onth esand ysoils . Ina larg eare abehin d the coastline,area swit hpea t forming vegetations existed togetherwit h reedmarshes andmars h forests.Alon g theriver s forests onnutrien t richalluvia l soils existed aswel l asmars h forests and reedmarshe s downstream. Inth enorther n regionbehin d the islands awadde nregion ,.tida lflats , existed changing landwards intosalting s and reedmarshes .

From thisorigina l situationma nmad epolde r areashav ebee ndeveloped . They canb e distinguished infou rmajo rgroups :polder s inth edownstrea m flatrive r catchment areas,polder s inpea t areas,polder s onth ebotto m ofdraine d lakes and polders createdb y coastal embankments (fig.2) .

Inth erive r catchment areas upper and lowerpart shav e tob e distinguished. Inth euppe rpar to nth e levees forests grewo nric h mineral soils and inth ebackswamp smarshe s and forestswer epresent , inth e lowerpar tmarshe s and forestswer edominating .

Inhabitation started on therive rbanks ,an d already incarlovingia n times settlements grewan d smallhors e shoe-shaped polderswer econ ­ structed discharging theirwate reithe r intoth erive r orbehin d the riverbank susin g thebackswamp s and the slopeo fth e land towardsth e sea. Inth e 12than d 13thcentur ypeopl ewer e ordered bymean s of"dik e letters"t oti e thedike s along theriver s together and combined polders were created.

225- higher grounds ^^^Hbottoms of lakes etc, reclaimed Plllll coastal lowland, endike d before 1300 ligner river flood plain îÊëç&Êiffl (inri so m e clay on peat and peat)

•ZZA lower river flood plain coastal lowland, reclaimed since 1300

r^-j peat land, reclaimed

Fig.2 .Th elocatio no f thepolder s indownstrea m flatrive rcatchmen t areas,i npea tareas ,o fpolder smad eb ydrainin g lakesan do f poldersmad eb y coastal embankments inth eNetherlands .

226 By theconstructio n of thesedike s and thedevelopmen t of an artificial watermanagemen t system these areaswer emor e andmor e transformed into agricultural land and theorigina lvegetatio n of forestswa smor ean d moredestroyed . Initially the land useaime d atcerea l production combinedwit h dairy farming and fishing.A s timeproceede d thelan d became less suitable for cerealproductio n andmainl y dairy farmingan d fishery remained. Inth e lowerpar t of the river catchment themarshe s andmars h forests were also gradually reclaimed.Th eorigina lmars hhabita twa s transformed intoa habita t ofwe t grasslands (onth edike s along the rivers special vegetationdevelope d that still,thoug h oftenpartially ,exists) .Wit h thedestructio n of the tidalmarshe sbird s like theGrea twhit eegret , theNightheron ,th eDalmatica npelica n and the Squaccoherro n lost their habitat toa larg eextent .

Amajo rpar to fdutc h polder areas consists ofpea t soils.Th e reclam­ ationo f these areas sometimes dates from theelevent h centurybu tth e majorpar tha sbee nreclaime d during the thirteenth century andlater . Inthes epea t areas,pea to fvariou s thickness overlaysmainl y loamy or clayey soils.Th epea twa soriginall y reclaimed forcerea lproduction . As timepasse dby ,du e tooxydatio n and shrinkage,th econstructio no f anartificia lwate rmanagemen t systemwa snecessar y tosav e thelan d fromflooding .Unde r those conditions the land could onlyb euse d for dairy farming. Grassland polder areasprovidin gmainl ywe tgrasslands , formed thehabita t forwate ran dmeado w fowl.

Inthes e areas themajo r and decisive step from anenvironmenta l pointo f view isth e first i.e. thereclamatio n of thesoil .Thi smean t the destruction of theorigina lvegetatio n on thepea tsoil s and turningit , after amajo r temporary use forcerea lproduction ,int ograssland . Theothe r result of the construction ofpolde rarea s isa decreas e inth e frequency of flooding ofvariou s areas and control ofth ewate rlevel , both of theope nwate r and of thegroun dwater . The reclamation of the landofte n started froma ban k of arive ran d penetrated bymean s of long stretched parcels intoth eare a tob e reclaimed.Th e origin ofth e formationo fthes e long stretched parcels isdu et o thecentra l government thatwa s already present at thattime .

- 227- Duet o legislation afarme r could only renta certai n (limited)lengt h of land alonga ban k forreclamatio nperpendicula r to thatbank .Thi s resulted ina differenc e inth e intensity of theagricultura luse , forced upon the farmerb ybot hdistanc e and soil conditions.I nth e oftennaturall ywel ldraine d areasnea r thebasi s of the reclamation (andmostl ynea r the farm)th e landwa smuc hmor e intensively used than theremote ,somewha twette rpart s at theothe r end of thereclamatio n parcels.The ywer eonl yuse d forha y cropping.Suc hhay-land swer ean d are froma necologica l pointo fvie wvaluable .The yprovid e good living conditions forman y specieso fmeado wbirds ,bu t are also important from afloristi cpoin t ofview .I nthes eregion sbird s liketh eCorncrake , theBâillon' scrake ,th eWhit e storkwer e commonalthoug h theyhav eno w almost completely disappeared from theseareas .

Figure 3show s atypica l exampleo fthi sparcellin gwhic h canstil lb e found inth eNetherlands . Howeverdu et oth e improvement of farming conditionsb y e.g. lowering of thewate r levels,th eapplicatio n ofartificia l fertilizeran d reallotmento f farms,muc ho f thisparcellin gha sdisappeared . Froma n ecologicalpoin to fvie w thisi sespeciall y reflected ina decreas ei n thenumbe ro fmeado wbirds ,rails ,Whit e storks,bird s ofpre y like harriersbu t also inth ediminishin g floralvalue s of theseareas .

The thirdgrou po fpolder s inth eNetherland s consists ofdraine dlakes . Natural lakeswer epresen t inth epea t areasbu t theyhav eals obee n formed byma nusin g thepea t asfue lbecaus e of lack ofwoo d orcoal . Inth ewester n andnorther n parto fou rcountr y thisresulte d inth e creationo f lakes anda syste m ofope nwater swit hman y small,lon g islandso nwhic h thepea twa s dried (fig.4) .I na numbe ro f cases the combined actiono fwin d andwave s resulted inerosio no f thesmal l islands and theformatio no f increasingly larger lakes,threatenin g the landsaroun d them. These areaswher e lakes,smal l canals,smal l islands andhay-land s in various combinations werepresen twer e important forbot hherbivorou s and carnivorousbird s ofwetlands .

228- Fig. 3.A typical exampleo f thelon g stretched parcelling inth epea t reclamation areas inth ewester npar t of theNetherland s (Holland- Utrech tregion). .

229 Fig.4 .A nexampl eo f thesyste mo f long stretchedwater s and islands resulting frompea tdiggin g for fuelproduction .

230 JIheinventio n of therevolvin g turretwindmil l enabled the lakes tob e reclaimed.Th e first lakewa s drained inth e firsthal f of thesixteent h century and especially inth ewester n part of theNetherland sman y lakes havebee ndraine d infollowin g centuries.Th emai npurpos e ofthes e workswa s the reclamation offertil e clay soils suitablefo rcerea l production,a swel l as for theincreas e of safety against devastation of the surrounding peatarea ,reducin g shore linean d improvemento f watermanagement .I ntim eth eemphasi s on theseaspect sha svaried ,bu t theyar e stillvalid . Theecologica l resultwa s adestructio no fth ehabita t forman ywate r fowlan dbird s ofmars h land,bu tals o formammal s like theOtte ran d theBeaver .

Inth e areao f thecoasta l polders adifferen t situation isfound . Here thepolder shav ebee nreclaime d from the saltings.Coasta l accretion could beenhance d bymakin g special sedimentationprovision swhic h still canb eobserve d inth eWadden-se a (fig.5) .Th ehighe r partso fth e saltingswer e first turned into salty grasslands providing food forman y herbivorouswaterfow l likeduck san dgeese . After embankment thecoasta lpolder swer epredominantl y used asarabl e land.Nowaday s the land accretion areashav eprove d tob eo fver yhig h ecologicalvalu e forbot h themarin e ecosystemo f theNorth-se a aswel l as forwaterfow l andwaders . The shallow,intertida l and sometimesbrackis h areas proved tob eo f suchecologica lvalu e that,i nrecen tyears ,i tha sbee ndecide d nott o execute embankment in such zones eventhoug hplan swer e advocated.

The largest land reclamation project inth eNetherland s isth eZuyder - zeeproject.Plan s for thisprojec twer e already advocated in 1657b y Henric Stevin,a Dutc hengineer ,bu t itwa sno tuntil l themiddl e ofth e nineteenth centurybefor e technical developmentsmad e theplan sfeasible . It tookman yyear so fdiscussion ,researc h and planningbefor e thefina l decision toexecut e thepla nwa s taken,i n 1918,b ypassin g theZuyder - zeeac t inparliament . Thebasi c aims of thepla nwer e toshorte n theprimar y coast lineb y the construction ofa barrie r dam,t oincreas e foodproductio nb y the reclamation ofapproximatel y 200,000h ao fne w land (160,000h ano w

- 231- Fig. 5.Lan d accretionwork s inth eWaddense aregion .

- 232 realized)an d an improvement of thewate rmanagemen t ofadjacen tregions , subjected tosalin e seepage from the sea,b y turning inth e formerZuy - derzee into the freshwate r lake:Lak e IJssel (IJsselmeer)b ymean so f theRhin e distributary theIJssel . Theexecutio n of theprojec tha sha d and stillha secologica lan d environmental consequences. Amajo r ecological consequence isth e change from thealmos t salinean d brackish systemo fth eZuyderze e intoa fres hwate r systemo f theLak e IJssel.Thi smean t forexampl e thedisappearanc e of the typicalZuyder ­ zeeherring ,th eanchov y ando fwaterfow l livingan d feeding along the coastline and inshallo wwater s like theBrentgoose . On theothe rhan d there aregain s too. Thewate r inLak e IJssel iseutrophi c and,althoug h under influenceo f theRhine ,stil lno theavil y polluted.Du e toit seutrophi c character the large lakes inthi s systemar eric h infoo d forwaterfow l feeding onfis ho rbenthos .Nowaday s themollusc ,Dreissen apolymorpha ,whic h wasonl y first observed here in 1937,i sth ebasi c food forbentho s feeding ducks.Th e Smelt is thebasi c food forman y fish eating waterfowl.Th eare arank sver yhig h on the listo fvaluabl ewes t european areas forwaterfowl . Also inth epolder s part of thene w land nowadays issave d for ecological developments;marshes ,grasslands ,wood s and forests arean dwil lb e developed providinghabitat s forwaterfowl ,bird s ofmeado w landan d various rare orendangere d species sucha sharriers ,spoonbill s and herons.I nth epolde r SouthernFlevoland ,whic h isno w under development approximately 15,000h a ofnatur e sanctuary and forestwil lb erealize d ina polde ro f43,00 0ha .Thes edevelopment s have tob e considered in relation toth e roleenvironmenta l and ecological aspectshav e played inphysica lplannin g inth eNetherland s during thelas tdecennia .Whic h brings us toth e second parto f thispaper ,afte r concluding thispar t with ama p of thepresen t dayecologica l situationo f theNetherland s as iti snowaday s (fig.6) .

Inth eNetherland sdurin g the20t h centurya numbe ro fdevelopment s took place,resultin g (asi nman yothe rcountries )i na stron g awarenesso f the importance of themaintenanc e ofa goo d quality of the environment and thepreservatio n ofnatur e asvaluabl e elements for thewelfar eo f mankind.

- 233- NORTH SEA

NATIONALLY IMPORTANT NATURAL LANDSCAPE ELEMENTS ^^^H I ^^^H almost everywhere or in large sections I almost nowhere

I I in many varying to in few places J urban use

Fig. 6.Th eecologica l situationo f theNetherland s around 1975 (after Atlasva n Nederland).

234 Developments inth e20t h century

The change of anagricultura l society intoa moder n industrialized and urbancommunit y togetherwit h alarg e increase inpopulatio n and astil l continuingmechanizatio n inagricultur e are important inthi srespect . The awareness of thepreservatio n ofnatur e originated fromurba narea s aswel la s therecognitio n of the importance ofgoo d environmental conditions and thenee d toreduc e thevariou s causeso fpollution . Already inth ebeginnin g of the20t hcentur y (byprivat e initiatives) the firstnatur e sanctuary,th eNaardermeer ,wa spurchased .Earlie r efforts toreclai m the lakeha d failed and itwa s thenplanne d tob e filledwit hurba nwaste .Startin gwit h theNaardermeer ,th eprivat ean d government organizations fornatur e preservation acquired 136,000h ao f nature sanctuaryo fdifferen t typesan d sizes throughout thecountry , togetherwit h 293,000h ao f forests (fig.7) .

Theenvironmenta lmovements ,begu nb ybook s sucha s "Silent spring"b y Rachel Carson,stresse d the importance ofcombatin gpollutio n injus t sucha nindustria l society sucha s theNetherland sha dbecome .Pollutio n ofwater ,soil ,air ,groundwater ,bu t alsonois e etc.ha d tob ereduced . New legislations in this field havebee ndevelope d inth epas t decennia andprogres s isbein gmade ,bu t stillman y problemshav e tob esolved , inth eurba n aswel l as inth erura l areas ofou rcountry . Prior toth e legislation concerning theenvironment ,th e legislation concerning thephysica lplannin gwithi n the countrywa smor e developed and elaborated. Starting fromnationa l planning forurbanizatio n and the development of therura l areas,regiona l and localplannin gwa s adjusted toon e to theother .A t the same time theproces s ofplannin gwa s gradually being democratized. Recently ala wconcernin g environmental impact assessment forne w projectsha sbee npropose d toth eparliament ,bridgin g and covering bothphysica l planning and environmental planning. However,i nspit eo f thisdevelopmen t ofa nelaborat elegislatio ni nth e field ofbot h planning and environmentalprotection ,ther eha sbee nan d is stilldamag ebein g done toth eenvironmen t of thepolde r areas.Thi s canb e illustrated by considering thedevelopment s inth e landus ei n ourcountr y during thiscentur y (fig.8) .

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Fig. 7.Natur e reserves and forest areas inth eNetherland s around 1975 (afterAtla sva nNederland) .

236 Area in ha x 10^

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280

forests, nature reserves and other uncultivated area (waste land)

260.

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1900 1910 1920 1930 1940 1950 1960 1970 1980

Fig.8 .Th edevelopmen t inth elan duse s inth eNetherland s duringth e 20thcentury .

237 As canb e seen the total areao f the land inth eNetherland sha s increased fromalmos t 3.2millio nhectare s toove r 3.3millio nhectares . This ismainl y due to thereclamatio n of thelarg eZuyderze epolders . During the first fiftyyear s of the20t h century the total areao f forest andwast e land decreased fromapproximatel y onemillio nhectare s to abouthal f amillio nhectare smostl yb y exploiting thewast e land. Themajo rcause swer e the introductiono fartificia l fertilizers,larg e unemployment inth e thirties and food shortages.Durin g thelas t three decennian o significant changes canb eobserved . However,importan t changes canb eobserve d inth esiz eo f theurba narea . Due toa ver y strong increase of thepopulation ,6 millio n around 1900, 8.5 million in 1945an d over 14millio n in 1981,togethe rwit ha n increase inth eus eo f theavailabl e spacepe rperson ,resulte d ina growth ofth eurba n areas fromabou t80,00 0hectare s around 1900t o about450,00 0h a in 1980.I tca nb e seentha tdurin g thelas tdecennia , theurba nexpansio nwa s realised at theexpens e ofth eare ao f agricultural land.Th eaverag erat e of thisproces s isnowaday s about 13,000hectare s peryear . Sucha proces s affectsman y polderareas ,sinc e themajo rpar to fth e Dutchpopulation -live s inth ewester n parts of the country,wher e predominantly polderarea s exist.Th e impact that such aspreadin g urbanization and therelate d infrastructure canhave ,ca nb erealise d by consideringmap s of theurbanizatio n inth eregio n around Amsterdam in 1930an d 1975.Nex t toth e towns andvillage s themselves,ther ei s anincreas e inth e zones ofdisturbanc y around themb y increased mobility of thepeople .B y setting thesedisturbanc y zones arbitrarely at 1.5k m in 1930an d4 k m in 1980,fro m theurba nborde ron eca nse e the increase of theeffec t ofurbanizatio nupo n theregio n (fig.9 an d 10).

Next tothi surbanizatio nprocess ,development s inagricultur e itself sucha sincreasin gmechanization ,th eus eo fartificia lfertilizers , ofpesticides ,th e improvement ofwate rmanagemen t and theexecutio no f large scale reallotmentplan s resulted ina decreasin g ecological value ofespeciall y the grasslands.Thei rvegetatio nbecam emor e andmor e uniform.Th emor e intensive useo f the land caused thedestructio no f manynest so fmeado wbirds ,althoug h some species compensated by starting

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Fig. 9.Th eurbanisatio n inth eAmsterda m region inth eNetherland s in 1930an d theurba ndisturbanc y zones (arbitraraly seta t 1.5k m in 1930).

239 North

va villages and towns road HIP WmmM planned town railway

urban disturbancy zone

Fig. 10.Th eurbanisatio n inth eAmsterda m region inth eNetherland s in 1975an d theurba n disturbancy zones at that time (arbitraraly set at4 k m in 1980).

240 breedingearlier . Excessive useo f fertilizers caused eutrophication ofcanal s and lakes and the changing of the aquatichabitat . Theus eo fpesticides ,suc ha sDD T and others,resulte d inth e introduction ofpoison s infoo dwebs ,a sdoe s thedischarg e ofurba n and industrialwastewate r andeffluents . Only inrecen tyear sha s theeffec t ofdumpin g industrial and urban wastes inpolde r areasbecom e evident.Sometime s urbanextension shav e beenrealize d insuc hregions .Afterward s itwa s observed that soil, groundwater and sometimes even surfacewater swer eheavil y pollutedby , forexample ,carcinogeni c solvents sucha sbenzen e and otheraromatics . Very expensive soil improvement planshav e alreadybee nrealize d inth e regionsnea rRotterdam ,resultin g incost s amounting toove rhundred s ofmillion s ofDutc hguilders . Inothe r locations,suc ha s in theVolgermee rpolde rnea rAmsterdam , thedumpe d industrialwast ewa s recently found tocontai n thever y toxic dioxine,threatenin g theenvironmen t ofbot h thecit yan d theadjacen t naturereserves .

Regarding thedevelopment s indicated above,i t isno t atal l surprising that inth ediscussion s about the final stage of therealizatio n ofth e Zuyderzeeproject,th eMarkerwaar d polder,ecologica l and environmental aspectspla y animportan t role inth edifficul t andalread y 10year s durationproces s ofdecisio nmaking .Th e finaldecisio n to construct thepolde rha s still tob e takenb y thegovernmen t and tob eapprove d byparliament .Grea t effortshav ebee nmad e togiv ereliabl ean d quantitative predictions of theecologica l and environmental consequences forbot h the aquatic ecosystem, thatbecome s smaller,an d the increasing possibilities fornatur e inth efutur epolder .Th e insightha sgrown . Whatha sremaine d isth e impossibility ofweighin g thetw oecologica l alternatives,althoug hmor e quantified thanever .

As awhole ,throughou t thecountry ,th e increase of thepopulation ,th e increase of industrial activity and theurba n expansion result ina spatial consumption ofpolde r areas andhenc e adestructio n ofremainin g ecological values.O nth e otherhan d theawarenes s of these processes and apolic y aimed atpreservation ,reconstructio n andnewl y developments

- 241- ofnatur e and its integration intoothe rmean s of land use,ca nhel p topreven t completedestruction . As aresul t itha sbee n observed that thenumbe ro f geese staying in theNetherland s inwintertim e shows amarke d increasedurin g thelas t tenyears .Investigation s inwester nNetherland s during the last ten years showed that thenumbe ro fbir d speciesbreedin g thereha s increased togetherwit h theactua lnumbe ro fbreedin gbirds .A nexceptio nwer eth e typicalmeado wbird s andherons .The y decreased innumbe ro f speciesan d numbero fbreedin gbird s forreason smentione d above. These losseshav ebeen ,althoug h partially,compensate d for inth ene w polders.

As alreadymentioned ,ther e isstil l apossibilit y for the construction ofcoasta l polders especially inth eWadde n sea.Althoug h anumbe ro f plans areadvocate d inth eNetherlands ,a swel l as inGerman y andDenmar k iti sver y unlikely that theywil lb e executed inth eNetherland s and Denmark.Whethe r thisals ohold s forGerman y isdoubtful . Inth eNetherlands ,i ti srealize d that thisWadde n regioni sto o important for thefoo dprovisio n forman ybird san d for theecosyste m of theNorthse a and that iti sto oimportan t forshrim p fisheryan d shellfish fishery tob eembarke d upon.

At thepresen t time there isa tendenc y inou rdensel y populated country torealis e aschem e ofphysica l planning ona nationa l level thatwil l reduce therat eo furba n expansion.I ti smor ean dmor e appreciated that theavailabl e space,bot h of land andwater ,i slimite d andscarce . The struggle and competitionbetwee nvariou s land uses canno toffe r solutionswher e available space ispermanentl y lacking.I ti s tob e expected thato na nationa l level agreementwil l evolveabou tth e distribution of the areaove r themajo r uses of theavailabl espace : agriculture,nature ,urbanizatio n (including recreation),forest san d water.Whe n this general agreement isreache d and accepted,th e integration ofothe r functionswithi n theprincipa l onewil lhel pt o differentiate theenvironmen t on aregiona l or local scale,whil eo n thenationa l level thedestructio n of thequalit y of theenvironmen t can beprevented .

242 Acknowledgements

The authors thankdr .ir .P.J . Ente forhi scontributio n inpreparin g themap s for the figures 1,2 ,6 an d 7an d ir.J.A.L .Barne s for correcting thetext .

References

Linden,H .va nder .Histor y of thereclamatio n of thewester n fenlands ando f the organizations tokee p themdrained . In:Proceeding s ofth e symposiumo npea t landsbelo wse alevel ,ed .b yH .d eBakke ran d M.W.va nde nBerg .ILR Ipublicatio nno .30 ,Wageningen ,1982 . Pons,L.J .Ecologica l map ofth eNetherland s inRoma n times (1974). In:Leve nme tbome ne nbossen ,J.F .Wolterson , 1974. Poorter,E.P.R .D e zilverreigers vand eOostvaardersplassen . In:D e Lepelaar,no .66 ,23-25 ,1980 . Rooth,J . a.o.Number s and distribution ofwil d geese in theNetherland s 1974-1979. In:Wildfowl ,decembe r 1981. Saeijs,H.L.F . andH.J.M .Baptist .Evaluati e vanWesteuropes eover - winteringsgebieden vanwatervogels .Deltadiens t nota 78-10,1978 . - Atlasva nd ebroedvogel s vanWest-Nederland . - Atlasva nNederland .

243- 244 ECOLOGICALVALUE SO FPOTENTIA L POLDERAREA S M.Vannucc i Unesco NewDelhi ,Indi a

"Ifw e areabl et obrin g about ineac h country aprope rblen do f ecological economics and economic ecology,on ewil l find thatth e work will turn from thepresen tmoo d of agony intoon eo f enduring ecstasy"- Dr .M.S .Swaminathan ,Meetin g ofICS USpecia l SurvivalCommittee .Ne wDelhi . 19-2-81.

From thepoin t ofvie wo f theenvironmen t -o rth eworl dw e livei n- thetw oprincipa l consequences ofwha t areusuall y called the"scientifi c and theindustria l revolution"are : (1)unchecke dhuma npopulatio ngrowth , and (2)dwindlin gnatura l resources,includin g decreasing genetic diversity.Th eproblem s createdb y thesetw ophenomon aar e compounded by evergrowin g demands forimprove d standards oflivin gconditions , which arei ntur npossibl e thanks toth econtinuin g scientific- technological growth andmor epowerfu l information and communication systems.

Manynatura l resourceswere ,unti l recently,considere d tob e available inunlimite d quantities,bu t itha s finallybee n realized thatnone , absolutelynon e isso .Th eocea n cannotb e used asa bottomles s sewage sink,no r is freshwate r inexhaustible;equall y finiteo na worl dwid e scalei sth efood ,fibe r andenerg y production potential.Eac h andever y ecosystem,ever y subsystem,whethe r arive rbasin ,a mountai n range,a forest,a villag e ora polder ,i sonl y part ofth emajo rEcosyste mEarth . Ecology isth estud y ofecosystems ,wher eb y definition andactua l fact, everything isrelate d toeverythin g else;ste pb y step,whateve rhappen s inth eYssel-lak epolder sma yhav e repercussions faran dwide ,i n unpredictablemanne r andwit h unpredictable consequences.

- 245- Long goneb y areth etime swhe nEurop e orAmeric a could ignoreth e vagaries ofth eMonsoo n inSout hAsi aan dwhethe rmillion swoul d starve todeat h orsurviv ean dreproduce .

There are,o fcourse ,tw opossibl eattitude s inrelatio n toth e environment;a passiv eon esaying :"le t thingsb e asthe y arean dw e shallse ewha twil lbecome" ,or ,i fyo uwish :"le t theavalanch e come asi tmay ,w ehop e toru nsomewhere ,fas t enough tosav eou rskins" . But there isals oanothe r attitudewhic h ismor eManl y andrational ,an d this is:"le t usd osomethin g about it and letu s avoid doingwha t shouldno tb e done".Thi s attitude of doan ddon' tma n shareswit h some other animals,lik ebeavers ,o rsom ebirds ,bu t typically human isth e willingness toaccep t and facea challenge ,whic h leads todrawin gplan s whereal lfactor smus tb e considered ona long termperspective .O n steering theperilou s coursebetwee n theScyll aan dCarybdi s of development orconservation ,ma n inth e longru n faces failures thatar e asnumerous ,t osa y theleast ,a s success stories.I nth eperspectiv eo f thepresen t symposium,i twa s thisattitud e thad led theVeneti i to occupy themarshland s onth edelt a of theAdig e andbuil d upVenezi aan d theVenetia n civilization;o rth eFrisians ,wh o slightly later started onthei r first attempts tobuil d dikeso nth eFrisia n islands;o rth e people fromKeral ai nIndi awh ohav ebee nknow n totam e theirbrackis h waters ina gam eo ftak e and givewit h these asinc ea nunprecise d many centuriesago .

There aresom ever y peculiar aspects toth eland/se ainterfac eecosystems . They areintensivel ydynami csystems ,usuall yhighl y productive,speciall y inthos earea swher e freshwate r from land drainage enter into the system.The y areals over yvariabl e inspac ean d time,a conditio ntha t requires thedevelopmen t of special adaptive featuresb y living organisms.Man' s interference incoasta l (land/sea interface)ecosystems , has invariablybee n oneo f tuning thesyste mb y reducing thevariabilit y ofit s parameters,bot h abiotic andbiotic .Thi s typeo fmanagemen t is unavoidable,becaus e itmean s preparedness against natural calamities such asunusuall yhig h tides,o rflood s from land drainage andrains , or,nowadays ,th ethreat s ofpollution ;thi s typeo fmanagement ,however , may alsobrin gwit h itunexpecte d andundesirabl econsequences ;

- 246- consequences ina wa y comprablet othos eo f agriculturalpractices , enhanced bymoder n technologies,suc h asmonocultures ,intensiv eus eo f pesticides,fertiliser s and soon .

Thebuildin g upo fa polder ,ecologicall y speaking,i sth erevers eo f conservation activities.I tis ,fo rinstance ,th eopposit e of establishing abiospher ereserve .Whe nw e establish areserve ,b y definitionw eavoi d introducing changes ofan ysort ,sinc eth esyste m ist ob e left undisturbed inorde r thatth enatura l transfer ofmatte r and energy amongcomponent swithi n thesyste m andbetwee n thesyste m andth e adjoining onesma yprocee d according toth esystems 'ow n laws.O nth e otherhand ,whe n apolde r isbuilt ,ver yofte n itbegin s fromscratch . Entirelyne wsoi l isaccumulated ,the nturne d into agricultural,urba n or industrial land.Thi s iswha t theAztecs ,fo r instance,ha d donewhe n theybuil t the floatinggardens ,whic hwer e literally floatingo nraft s inth elak eo fTexcoc obecaus e theyneede d soil inwhic h toplan t their vegetables (theremain sma y stillb e seen at Ochimilco,wher eth e floating raftshav ebecom e islands,throug h trees thathav egrow ntal l and taken root). Similarly theMaldivian s enlargethei r small coral reef islands formor espac eo nwhic h to liveb ybuildin g seawall san d groins to trapsand .Polder s and reclaimed land ingeneral ,ar ene w systems thatnee d tob emanage db y appropriatedo' s and don'ts.

Thebuildin g upo fpolder s inevitably takes spaceawa y fromadjoinin g systems,th econsequence s ofwhic hmus t alsob e considered inth elon g termplanning ,t omake n acost/benefi t assessment;certainl y the"robbed " systems alsoha d astructur e anddynamic s ofthei r ownan d aproductio n potential that shouldb eknown . Ifa tin y coral reef island isenlarged , areawis e itwil lb e less than aspec ko fdus t inth eimmensit y ofth e oceans,bu tma y cost a serious environmental impoverishment ifth e enlargement isa tth ecos t ofdestroyin g slow growing corals andth e rich faunaassociate dwit h them.

Polders arema nmad esystems ,i nwhich ,accordin g toplac ean d circumstances,th ebiologica l elementb y rank aso fprimar y importance, ormay ,perhaps ,b e totallyneglecte d except for theconvenienc e ofth e singlespecies .Man ,wh oneed s aplac e inwhic h to livean d spacefo r

- 247- recreation. Inothe rparts ,o fth eworld ,however ,polder s are considered entirely foragricultura l production,includin g inthi sperhap s also aquaculture,an dthe y includeman y different species,i nadditio nt o man theplunderer ,th especie s forwhos e exclusivebenefi t thepolder s arebein gbuilt .Ther eaire ,therefor e contrasting requirements -o r values,i fyo uwis h- accordingt oth eplac ean dpurpos e for which polders arebein gbuilt .Th eparameter s tob e selected,measure d and quantified for asoun dmanagemen t vary inessenc ean dmagnitude .Wha t maybecom ea "don't "i non earea ,coul dver ywel lb e themai n "do"i n another.Sinc epurpose svary ,an ds od ovalues ,"do "an d "don't"mus t bedefine d an«wi neac hcase .

Inth emanagemen t ofpolders ,lik ei nothe rsystems ,probabl y thegenera l aimwoul db e tobrin g aboutwha t Swaminathan called "aprope rblen do f Ecological economics and economic ecology".Ecologica l economicsha sa very difficult taskt operform ,becaus e ecologicalvalue s arehar dt o definean dqunatif y interm s sucha swoul db eaccepte db yeconomists , but itals o isa challeng e toth ehuma nmin d that isfascinate db y difficulties tob e conquered.Th e imponderables that determineth e quality of lifefo rma n and that contribute inn o smallmeasur et omak e of any endeavour ofthi skin da succes s or afailur ecas ear eonl yto o often leftou to f thepictur e and only aposterior i it isfoun dou t that such factor orothe r really shouldhav ebee n taken intoaccoun t because itplay s animportan t previously unsuspected role in,le tu s say,th efoo d chaino r inth etransmissio n ofdiseases .I nfact , everything is important,ever y species and every association ofspecies , because ifi tdi dno t play anessentia l role,i twoul dhav e long since beenweede d outo f thesyste mb y itsnatura levolution .

Since it is impossible toobtai ntota l informationo n everythingan d sincew ear echaracteriscall y always ina hurry ,w e cannotwai t tohav e complete informationo n everythingbefor e takingaction ,a compromise issough t and .... letu shop e forth ebest .

Almost alllif esupor t systems,almos t everywher e inth eworld ,ar e nowadays under stress,i f thebuildin g ofpolder s iscarrie d outwit h a singlepurpos e inmind ,a s for instance added space forman ,o r

- 248- economic development through industrialgrowth ,i tcoul dbecom ea disastrous enterprise.Monotonou s ecosystems are fragile,i ti s diversity that gives stability toecosystems ,whethe rnatura l orma nmade . Potential polderarea sma yb e found allove rth eworld ,a tlo wo rhighe r latitudes,especiall ylo wlyin g coastal areaswit h sandbars ,o rcoasta l lagoons,mangrov eswamp so rforests ,wetland s andmarsh y areas andalon g estuaries anddeltas .San dbar s arei nfac t usually thestartin gplac e whereengineerin gwork s forreshapin g thelandscap ebegin ,b ybuildin g dikes andwate r level control devicesb y sluice gates orspillways . Often theimpounde d area,afte rwate r isdraine d off,i s lyingbelo w sealevel ,als o inman yplace s inth etropics .Coasta l lagoons are admirably suited and innumerable couldb e cited.Fo r instance,alon g the800 0k m longcoas t ofBrazil ,th eLagô ado sPato s andLago aMiri m coverhundred s ofsquar ekms .Extensiv ereclamatio nha sbee n carried out allalon g itshistor y inth eBaî ad aGuanabar a (Riod eJaneiro )an d many of thecoasta l lagoons areunde r intensive aquaculture (ex.Lagô a deMaricâ ,nort h ofRi o deJaneiro )throug hmanage d impoundments of brackishwater ,a practic e introduced inth eearl yXVI Icentur y for thePortuguese ,wh oha d inherited theknow-ho w from theRoman s anduse d thesam emethods .Eve nnow ,gre ymulle t ponds inth eare aof ,fo r instance,Recife ,ar ecomparabl e toth eacquacultur e impoundments inth e Campania,an dothe rplace s insout h Italy,wher emethod s arestil lver y muchwha t theywer e almost 2000year s ago.Values ,however ,hav echange d andwork swhic hwer e carriedou tmainl y tomanag e thenatura l systemt o put itt oa highe rproductio n level for those itemso f interest toman , like fish,hav eno w givenwa y towork s forexpandin g traffic areasan d improve communications,buil d airstrips andairport s or enlargeth e industrial area.Thi swa s donever y often ina hurrie d manner,withou t dueconsideratio n toloca lphysiographi cconditions ,speciall ywate r circulation andmajo rproblem s ofpollutio nhav e cropped up.Time shav e changed,s ohav eneed s andth emean s tosatisf y them.

InAsia ,th epractic eo fbuildin g dikes for impoundingwate ran d developing low lying areas isa practic etha t goesbac k toremot etimes . Thepeopl eo f theMoenjo-Daro/Harappa n civilisationbuil t canalsan d harbours inwhic h theflo wo fwate rwa s regulated according toth eneed s ofnavigatio n of their large covered two-three deck ships as earlya s

- 249- thelast efourt hmilleniu mBC . Inpresen t day Indiather e are2 millio n hectares ofbackwaters ,30,00 0hc t ofwhic h areunde r aquaculture,mainl y forprawns .Thes e include thedelta s and estuaries ofmajo r riversa s well as coastal lagoons and lakes.Lo w cost,labou r intensive,simpl e technologies arestil l inus eeve nwher eextensiv e engineeringwork sar e involved.Traditiona lmethod s andtechniques ,tha thav eprove nthei r worth over centuries arestil l inus eofte n incontras t inth esam e areas,wit hmoder n technologies.Thu s inth eCochi nbackwater s (Malagar coast,southeas t India),th ebun d across theVembana dLak e isbein gbuil t over aspa no fdecade swhil e furthernorth ,i nth esam ebackwater s several polders andne wwaterway swer e recentlybuil t inonl y a fewyear s forth edevelopmen t ofCochi npor t and Cochinshipyard .Th eCochi n backwaters area particularl y interesting example.I t isa vas tare a that extends fromabou t 9 lat.N .t oles stha n 7 lat.N .Extensiv e "bunding" (dikebuilding ,wher edike sma yb e simplemu dwall s 50-100c m high abovemea nwate r level andrepaire dyearl y after theS Wmonsoo no r major structuresbuil twit h rocks andothe rmaterials )ha s turned anare a that includesman y taluds of threedistrict s intoa polde r lyingbelo w sealevel .I nthi sare a fields aremanage d forric ecroppin gan d aquaculture alli none .A specialvariet y ofpadd ywa s developed over theyear swhic h issalinit y tolerant,brakis hwate r isadmitte d during theintermonsoo nperiod ,fo raquacultur e purposes.Th emanagemen to f thisare aha s characteristics ofit sow n and problems of allsorts ,no t leasto f themthos eo f landan dwate r use taxationan dsocia l relations thatbecom eacut eno w andthen .Th eKuttana d areai st othi sda yth e ricebow l of theStat eo fKerala . Inothe rplaces ,i nth esam ebackwater s and outsideo f theVembana d Lakeprotectiv ebund ,smal l areaswhic h 2 . . . . . collectively cover some50 0 km areindividuall y dikedof f intofield s flooded during theS Wmonsoo n forpadd y cultivation and some fishals o arereare d alongwit h paddy.Afte r reaping therice ,whe nmonsoo n fresh water fromrain s and landdrainag e have ceased topou r in,brakis hwate r gradually inundates thebackwater swher emaximu m salinity reaches 31-32% atmost .Durin g thisperiod ,th esluic egates ,provide dwit h special nettings areopene d during the incoming tidet oadmi t intoth efield s thelarva eo fprawns ,mainl y Penaeus indicus.Th elarva egro wi nth e same fieldswher epadd y grewdurin g themonsoo n under 1-2%salinity . Theprawn s (chemmeen)ar eharveste dbefor e theonse t of thenex tmonsoon ,

- 250 when,i f they could escape,the ywoul d migratebac k tose at o metamorphose intoadult s and assemble at acertai ndistanc e anddept h offshore,wher e thosetha tha dno tbee ntrapped ,ar eabl e tomat ean d reproduce. Thebund s thatmak eu p thecheckerboar d of fields areplante d with coconuts and chinese overhang themajo r canals.Th ewaterway s are,i n addition,th emajo rway s ofcommunication , transport ofgood san d passengers aswel l asmail .Mos t of thetraffi cwa sdon eunti l recently and stillvastl y soa tpresent ,b y "village"craft ,unmotorise dan d propelled by oars andpoles .Th eowner s of thefield sd o theplannin g of thepadd y andharves t thecoconuts ,bu t fieldsar e leased to fishermenwh od o thepraw ncultivatio nan dwee d themfro m carnivorous fish,allowin g only thegrowt ho fharmles s specieso f fish inadditio n toprawns .Th e success orfailur eo f thepraw nharves t isalmos t entirely due to theabilit y and expertise of theelde r fishermanwh o operates thesluic egate sa t theappropriat e time tole t inth elarva e which hecanno t seean d doesno tkno w they exist.N o fertilisers are used excepthuman ,fis h and prawnexcreta .Th eproductivit y infis han d prawnaverage s 2,300kg/hct/season .I tcoul dwel lb e increased bymoder n techniques.

Thereaso nwh y Ihav edeal ta t some lengthwit h thisparticula r example is,first ,I a mfamilia rwit h theare aan dhav e firsthan d information but therear eman ymor e similar systems inIndi a andAsia ;second ,i t isa goo d exampleo fwis e tradionalus eo fnatura l ecosystem,an d the humanan d ecologicalvalue s attached toit .Th eCochi nbackwater smus t undoubtedly havebee na majo rmangrov e areai nth eremot epast .Small , isolated pocketsma y stillb e found.Th e conversion of amangrov e ecosystem,whic h isa highl yproductiv e one,althoug h of reduced direct utility toman ,int oa differen t ecosystemwit h amuc hhighe r production rateo f crops ofdirec tus e toman ,wa s achieved gradually,ove r centuries ofhar d labour and through theaccumulate d wisdom ofpeopl e who live inclos e communionwit h thesyste m ofwhic h they areals oa n important component.I woul d presume that,a s theywer eunti l acoupl e ofdecade s ago,th eCochi nbackwater shav ereache d theirmaximu m productionpotential ,excep tfo rimprovement s thatcoul dhav ebee n introduced throughmoder nagricultura lpractices .Troubles ,however ,

251- startedwhe nfertiliser s and pesticideswer euse d upstream andwer e flushed through thesyste mwit hmonsoo n landdrainag ewater .A t the same time,othe rpollutin g agents also set in,suc ha soil ,increase d siltation,increasin g sewagedischarg e fromgrowin ghuma n settlements and towns and the tampering of thenatura lhydrographica l patterno f circulationdu e toth econstructio n ofharbours ,shipyards ,airstrips , jetties and the like.I naddition ,labou rha sbecom emor e expensive whilehar dwor k isnecessar y tokee p thestructur e of thesyste m in proper order throughout theyear ,includin gdesiltin g of canals,repai r ofbunds ,sluic egates ,nets ,plowing ,th efield s mud flats,tendin g the coconut trees and soon .Muc h of the labourdon eb y local traditional expertswa s takenove rb y theLan dDevelopmen t Corporation thatuse s mechanisedmethod s thatca nd o thejo bquicke rbu tperhap s lesswell . Theexcessiv eus eo f fertilisersupstrea m caused eutrophication ofth e "lake"water s andmuc h of thebackwater shav ebecom e coveredb ywate r hyacinth,hamperin g navigation and causing all sorts of troubles.I n "old times"appropriat edrainag e canalsremove d excess salinity from thebelo w sealeve l areas and themonsoo n rains couldwas h off the sulphides and theacidit yproduce d during theperio d of stagnantwaters . Paradoxically,improvement sintroduce d throughmoder n technologies have created previously unknownproblem s and onereaso n istha t anatura l ecosystem,eve n if already domesticated ant tamedb yman ,canno t take abrupt changes;i tneed s aperio d ofadaptatio n and acclimatization to thene wconditions .A tpresent ,a lo to fmone y isbein g spento n research and survey inorde r tocorrec t theimbalance s produced.Th e Netherlands themselveshav e aschem e inth eKuttana d areaan dUNESC O mayhel p inconductin g someresearc hprojects .W emight ,perhaps ,clos e the circlean d come to theconclusio n that itcoul d notb ebette r than what centuries of experienceha d achieved.

Ifw e try tocompar e theDutc hpolders ,th eachievement s and problems inthi scountry ,with ,perhaps ,th eCochi nbackwate r system,w ewoul d perhaps conclude thatn oparalle l ispossible .W ewoul d be comparing systemswit h totally disparaging ecologicalvalue s and the conclusion is thusunavoidabl e thateac h case isuniqu ean dmerit s aspecia l study.Specia l studies thatwil l and do,i npractice ,increas eou r understanding of estuarine,deltaic ,an d low lying coastal areasi n

252- general.Th e typeo f reclamation thatma yb e advisablefo ra territorially small country asHollan dma y be theonl y solution tobi g problems of spacean d agriculture,eve na t thecos to f sacrificing important "ecologicalvalues" .The ymay ,however ,wel lb e totally inadvisable inothe r areaswher e these sameecologica lvalues , includinghuma nvalues, tak e theprecedence ,sinc e thewhol e system has already evolved over thecenturie s tosuc ha leve lo f perfection that theonl y likely improvementswoul db e theus eo fmoder nmethod s toincreas e theproductio n level.Unde r thisI woul d include the productiono fhighe ryieldin gvarietie s ofpaddy ,startin g from those varieties thatar ealread y adapted toth econdition s at large,th e samefo r coconut,prawn s and other specieso f fishan dmolluscs .Th e bundscoul db e improvedmaterially , thehydrograph ybette r understood and themanoeuverin g of thedoor s (orgates )shoul db ebase d ona scientificunderstandin g and explanationo f theancien t empirical wisdom.

Theproble mwoul d alwaysremai no fdrinkin gwate r supply.Typically , inth ereclaime d areasbehin d theVembana dLak ebund ,tubewell s only bringu p foul smellingwater ,obviousl y duea sexpected , to thehig h contento fsulphides .

Inconclusio n Iwoul d like tosa y that inkeepin g our eyesope n toth e factn o total conservation ispossible ,w e should,a si sno wbein gdon e inth eNetherlands ,tr y toanalys e allfactor s carefully,wor kou tcost / benefitbudge t analyses and try tofin d outal l the important factors thatma y perhapsno tappea r tob e sucha tfirs t sight,tha tma yb e difficult toquantif y and thatma y remain indisguis e and unperceived fora lon g timeeve ni f inth e longru nthe ywil l turnou t tob edeciviv e indeterminin g thequalit y of lifeo f thepeople .

- 253 SPECIALKEYNOTE S

- A. Volker. Lessons from thehistor y of impoldering inth eworl d - B. Verhoeven. Polders of thefutur e

- 255- 256 LESSONS FROMTH EHISTOR YO F IMPOLDERING INTH EWORL D Prof. ir.A .Volke r Delft University ofTechnolog y Delft,Th eNetherland s

Thehistor y of impoldering inth eworl d iso finteres t toth ehydrauli c engineerprovide d thattechnica l problemswer e solved underdifferen t conditionswit h themean s available during differenthistorica l periods.

Thehistor y of impoldering inth eworl d iso finteres tt oth ehistor yo f thehuma n civilizationprovide d that ananalysi s ismad eo f thefactor s which indifferen t societies and atdifferen t times inhistor ywer e determinant for impoldering.Histor y canb e instrumental inbette r understanding thepresen t conditions and in indentifying thefactor s which played arol ei nhistor y andwhic hwil l continue topla y arol e inth efuture .

Thehistor y of impoldering cannotb edivorce d from thehistor y ofth e topics of flood protection,drainag e and irrigation. Indeed, impoldering isa specia l formo f integral reclamation and involves acombinatio no f flood protection,artificia l drainage and oftenirrigation . Thehistor y of flood protection,drainag e and irrigation is,mos t unfortunately, alittl e explored area.

Inthi s essay anattemp twil lb emad e toanalyz e thefact s fromth e history of impoldering so that somefactor s canb e indicatedwhic hhav e been determinant inth epas t andwhic hwil l alsopla y arol e inth e inth efuture .

257- 1. Ancient polders

Inthi s sectionsom efact swil lb epresente d about early impoldering activities.A nanalysi s of thetechnica l and socio-economic factors, whichwer econduciv e toimpoldering ,wil lb eelaborate d insectio n4 .

Impoldering is aspecia l typeo f land reclamation applied tospecifi c landscapes. Itcomprise s flood protection,artificia l drainage andofte n irrigation and forthi s reason thehistor y of impoldering isa par to f thehistor y ofhydrauli c and agricultural engineering forachievin g floodprotection ,drainag e and irrigation.Unfortunately : "engineers havemad ehistory ,the yhav eeve nchange d thefac eo fth eearth ,bu t they failed torecor d it".Th ehistor y offloo dproctection ,drainag e and irrigation isa nalmos t unexplored field and iti sonl y recently thatth e"Internationa l Commissiono nIrrigatio n andDrainage " (I.C.I.D.)decide d tosolici t international co-operationfo rwritin g thathistory .

ProfessorHitosh iFukud a fromJapa n (1976)consider s theembanke d flood basinswhic h inancien tEgyp twer euse d asretentio nbasins, an d inth e saturated soil ofwhic h acro pwa s grown after theNil eflood ,a s "polders".Thes ebasin s dohav esom e commoncharacteristic s with the systemswhic h areusuall y called polders and asexis tto-day ,al si n Egypt,i nth ereclaime d lakes inth enorther n part of theNil edelta , butwhic h function ina nentirel y differentway . If thedefinitio no f ProfessorFukud a isaccepted ,th eoldes t "polders"i nth eworl dwer e reclaimed inEgyp t somefiv ethousan dyear sago .

Ifhoweve r theseNil ebasin s areno t considered aspolder s oneha s to looka t those ancient civilizations whereth econtro l ofwate rplaye d apredominan t rolean dwhic hwer edenote db yK .Wittfoge l (1957)a s hydraulic societieswit h ahydrauli c agriculture.Man y thousandso f years agoembankment s asmean s offloo dprotectio n and irrigation canalswer ebuil t inEgypt ,Mesopotamia , inth evalley s of theIndu s and theGange s and inChina ,Per u and CentralAmerica ,bu t it isno t certainwhethe r thework s canb e defined as impoldering as iti s understood to-day.

258- PaulWagre t (1959)ha s drawnattentio n toth ereclamatio ndurin g the fourthmillenniu m of themarsh y low-lying areas ofMesopotami ab y the Sumerians.The yskilfull ymaintaine d theseprehistori c polderswhic h are criss-crossed by ditches and canals.A Sumeria n text tells of the farmer Enkimdu,"Lor d of theditc h and thedyke" .Th efac ttha t theditche s are so expressively mentioned may indicate that thework s comprisedmor e than flood protection. Indeed reclamation ofmarshe s nearly always involved impoldering.

Sofa ra sEurop e isconcerne d Wagret considers thereclamatio nb y the Etruscans of thePontin emarshe s inItal y some twenty-five centuries ago as thebeginnin g of impoldering inEurope .Th eEtruscan swer e renowned asgrea t engineers andma yhav eacquire d thescienc e ofhydraulic s through trading connectionswit hMesopotamia .Th ework s feel indisus e after the third centuryB.C .an dwer eno t restoreddurin g theRoma n Empire.

Forth epurpos e ofthi s study themer equestio n ofsenorit y orantiquit y isno t so important.Mor e canb e learnt formcase swher e informationi s available as to thetechnolog y and thesocio-economi cframewor k inwhic h impolderingwa s carried out.Thu s twocountries ,th eNetherland s and Japan,com e to thefor ewher e theeminen t role theyhav eplaye d inth e history of impoldering datesbac k to thelas t thousand years only.

Inbot h cases theorigi no f impoldering and tidal land reclamation is obscure and oneha s towai t toth e 16than d 17thcenturie s A.D.befor e it canb e clearly seenunde rwha t conditions impolderingwa s carriedou t andwhy .Nevertheles s theearlie rhistor y isstil lo fsom e significance forth epurpose .

2. History of recent impoldering inth eNetherland s

Longbefor e thebeginnin g of theChristia n erapeopl eha d settled on thecoasta lmarshland s of theNetherlands .Ther ewer en o seadike s and duringperiod swit h abnormally high sealevel s causedb y stormsurge s inwinte r theysough t refuge fromfloodin go nartificia lhillock s (."terpen"o rdwellin g mounds). Shortly afterA.D .80 0thi s systemo f

- 259 passive defence against these aflood swa s gradually replaced by amor e activedefenc e inth efor mo f coastal embankments,firs t asdike s connecting thedwellin gmounds ,late r asdike s encircling landarea s destined forgrazin g and growing crops so inmor e offensiveway . Inth e period 1000-1200,man y damswit h sluices inth ecreek swer ebuil t enabling somedegre eo fwate r control inth eembanke d areas,thu s creating thefirs t realpolder s inth eNetherlands . Inth esam eperio d inlandmarshe swer e reclaimed thus creating inlandpolders .

Why didpeopl ed oal lthis ?Becaus e of increase inpopulatio n and the associatednee d formor e food? (Malthus).Becaus eo fa ris e of these a levelaccompanie db y landsubsidenc e (challeng*) e and response).Becaus e of cultural aspirations and thedesir et ocreat e citieswher e lifewoul d bemor e enjoyablean dwhic hwoul dmad e itnecessar y to reclaimnearb y forfoo dproduction ? Onei sno t sureabou t itbu t these incitements played arol ei nman y recent cases of land reclamation.

Thatpeopl edi d settleo n thecoasta lmarshe smor etha n two thousand years ago isunderstandabl ebecaus e these lands offered better possibilities for alivin g thanman y poor sandy and dry lands inth e immediatevicinity .The y couldno t foreseetha t their situationwoul d deteriorate inth ecours eo f timean dtha t their successors wouldhav e tofac e enormous problemswit h respect tosafety ,drainage ,foundation s of structures,se awate r intrusion andwate r quality.Perhaps ,the ydi d notworr y asmuc h about thefuture ,a sman y peoplenowaday s thinkw e should do.I fon ewant s inengineerin g circles inthi s country tosho w its intelligence,on eshoul d statetha t if two thousand years agother e hadbee n aphysica lplannin g institute inEurope ,th e low-lying parto f theNetherland swoul dneve rhav ebee n identified ason eo fth emos t promising areas forhuma n settlement and intensive economic development. Actually ourdistan tpredecessor s tookth erigh t decision independently

*)Th e relative subsidencewa smentione d forth efirs t time ina sessio n of theCour t ofHollan d asearl y as 1570.I n 1730th esubsidenc ewa s estimated at3 0centimetre s in 100years ,a figur ewhic h isno tto o far fromth ecorrec tone .

260- of thephysica l planners inafte ryear s and that decisionwa s toimpolde r andt oaccep t allth esid eeffect s and consequences of thatdecision . Towards thebeginnin g of the 16th century atechnica l innovation is appearing on thehistori c scene acting as a"vector "o rvehicl efo rth e transferfor mon etechnica l erat oanother .I ti sth ewindmil lwhic h wasmad esuitabl e fordrivin g drainagepump sb yprovidin g themil lwit h a revolving caps o that thewing s couldb eturne d according toth e direction of thewind .

Up tillthen ,lik e inothe rpart s of theworld ,drainag eha d been effectuatedb y gravity flowusing ,i nth ecoasta l areas,th etida l variations.Wher en ogravit y flowwa spossible ,variou s typeso fpump s wereuse d fordrainag e aswel l as for irrigation drivenb yhuma no r animalpower .Thi s technologyha s itsobviou s limitations and the reclamationb y dryingu po fnormall y submerged lands,lik elakes , lagoons and tidal inlets could onlyb e achieved byusin gwin dpowe r which,i nth eNetherlands ,i sreadil y available.Th e timeo f acceptance of thisne wfor mo fenerg ywa smor e thana centur y andth e environmentalists of that timeoppose d theinnovatio no n theground s thatth erepidl y rotatingheav ywing s wouldb ever y dangerous toma n and that thebird swoul d stoplayin g theireggs .

Anothertechnica l innovation,meetin g less opposition,wa s the introduction of theso-calle dmu d mill, theforerunne r of thebucke t dredger,enablin g tomov e earth underwater .Als oth efirs tmanua lo r textbook oncivi l and agricultural engineering aspects oftida l land reclamationwa s published. So thetechnica lvector swer e therebu t this condition isno t sufficient toexplai nwha thappene d inth e Netherlands towards theen d of th 16th century and during thebette r parto f the 17th centurywhe n reclamationb y impolderingwa s carried out ofman y inland lakes and tidalforeland s andwhic h formon eo fth e peakperiod s inth ehistor y of impoldering inthi scountry .

In fact thisperio dwa s also the "GoldenAge "o f theNetherlands ,a periodwit h overseas trade,succesfu lwa r against England and- a t least till thelatte rpar t of thecentury -friendl y relations ofa "Real-Politik"-type with France.A ne wsocia l class of self conscious

- 261 - richmerchant s camet o thefore ,busines sme nwh ower e looking for oppertunities forcapita linvestments . Professor Slicherva nBath ,wh o studied theagraria nhistor y ofWester n Europe inth eperio d 500-1850,ha s drawn theattentio n toth epric e revolution inth eyear s 1550-1650whic hh e attributed toa n increaseo f population and an increaseo f (gold)currency .Th efirs t repercussion was aris ei nprice s of foodstuff ,i nth efirs tplac e of cereals.Thi s created favourable economic conditions foragricultur ean d fora n expansion of thearabl e area.Reclamatio no fne w landwa s undertakenno t only inth eNetherlands ,o r"Unite d Provinces",a sthe ywer ecalle da t that time,bu t also inEngland ,Franc e and Italy.A s far asthi swa s carried outb y impoldering Dutch expertswer e often invited toparticipat e andther ehav eeve nbee n cases of capital supplyb y Dutchbusines s houses.

Slicherva nBat hha s shown that thereexist s aclos ecorrelatio nbetwee n theinde xprice s ofwhea t and theacreag eo f reclamationb y impoldering inth eNetherland s during theperio d 1500-1900.Th emos t striking feature isth esudde n drop of thelatte raroun d 1675an d the small activity during the 18thcentury .Thi s goes alongwit h adro po f thewhea tprice s butwa s this theonl y reason?Ther eha dbee n around that datea n important change inth epolitica l relationswit hFrance .Loui sXI V (+ 1715)ha d abandoned therealisti c policy ofhi s predecessors like CardinalMazari n and Cardinal Richelieuwh oha dmaintaine d business-like relationswit h theUnite d Provinces.Misle db yhi s ambitions LouisXI V wagedwa rwit h theUnite d Provinces whosuffere d aseriou s defeat in 1672,a blo w fromwhich ,accordin g toa nEnglis hhistorian ,th eUnite d Provincesneve r fully recovered.Durin g thenex t century anddurin g theNapoleoni c eraver y littlewa s achieved inth efiel d of impoldering.

Themos t important activity during thenineteent h centurywa s thedryin g upo f theHaarlemme rLak e in 1852,wher enowaday s SchipholAirpor t is located.Agai n adecisiv e technicalvecto r appeared inth e formo f the steamengine s fordrivin gwate rpumps .I twa s justified on theground s that thelak e threatened theadjacen t land areasb ywav e erosion.Th e cultivationo f thedrie d up lands almostbecam e afailur ebecaus eo f too little interest inth esocio-economi c aspects of theundertaking .

- 262- Inthi s century the largest impoldering scheme inth ehistor y ofth e Netherlandsha sbee n implemented and almost completed. It isth eZuider ­ zeeproject ,th eenclosur ean dpartia l reclamation ofth eZuiderzee . Itdiffer s frompreviou s schemesno t onlybecaus e of itssiz ebu t also because of itsnature :i t isa typica lmulti-purpos e scheme aiminga t an increase insafet y against floods,gai n ofarabl e land,sitin g for newcitie s and industries,haltin g saltwate r intrusion,storag eo f freshwater ,improvemen t ofdrainage ,shortenin g of road communications, etc.Thi s isrecen thistor y andw e could,perhaps ,no tye t take sufficient timedistanc e tob e ablet ogiv e ahistori c evaluation. Some essential independentvariables ,however ,ar eeasil y identifiable: availability ofpowerfu l technical equipment,respons e toth edefea t causedb y thestor msurg eo f 1916,damag edu et osal twate r intrusion, need formor e arable land,etc .Ye t onema y doubtwhethe r inanothe r caseth einpu to fthes evariable swoul dhav eproduce d asimila routput . Isther e stillanothe rvariabl e thenwhic h -s ofa r- ha sno tbee nme t onth ehistori c scene?

Itappear s to theautho r that thisvariabl ewa s thehig h degreeo f authority and self-confidenceo fGovernmen t andParliamen t who in 1917 took theformidabl e decision to implement theZuiderze e schemewhic h would changeth egeograph y ofa larg epar t of thecountr y forman y centuries tocome .Thi s inspit eo f theoppositio n ofth e environmentalists oftha t time.On ema y doubtwhethe r thepresen t generation and itspolitica l representationwoul dhav e thecourag ean d thepowe r totak e adecisio no f that scope to-day.Fea ro fpressur e groups and lacko fvisio n areth etw ovariable s producing nowadays negativeeffects .

3. History of recent impoldering inJapan .

Impoldering is anancien t technique inJapan . Itwa s carried out ina physical and cultural setting entirely different from thato fth e Netherlands.Fo r about two centuries development tookplac e independently from thetechnique s of thewester nworld .Nevertheles s thereexist sa striking parallelismbetwee nJapa n and theNetherland swit h respectt o thefactor s thatwer edeterminan t for impoldering.

- 263 InJapa npadd y fieldswer e cultivatedmor etha n200 0year s ago and also tidalan d landreclamatio nb y thefarmer s isa ncenturie s oldpractice , althoughno t asol d as inChina .Unfortunatel y little isknow n about technology and othervariable s that conditioned thereclamatio nb y impoldering.I nannal s theyea rA.D . 1284i smentione d asdat o ofth e first tidallan dreclamatio nnea rKawajiri ,bu t thisma yhav ebee n development of land raisedb y riverdeposit s and tectonicmovements . More isknow n about themor e recentperio d of theen do f the 16than d beginningo f the 17thcentury ,a perio d ofgrea t activity inth efiel d of impoldering,a perio d coinciding remarkablywit h thepea kperio do f reclamation inth eNetherlands .Thi s fact and thefac t that theDutc h East Indies Companywa s allowed from 1600onwar d toexploi t acommercia l house atNagasaki ,Kyushu ,ver y close toth esit ewher etida llan d reclamationwa s carried out,hav e ledsom epeopl et o thebelief ,tha t Japanese technologyo fimpolderin go ftha ttim ewa sinfluence db ya transfe r ofDutc htechnology . Itma yb equestione dwhethe rthi si strue :whe nstudyin g onlocatio ntraditiona lmethod so ftida llan dreclamatio ni nJapa nth eautho r couldnotfin dan yindicatio nfo rsuc ha transfer .I nhi sopinio nJapanes e impolderingtechnolog ydevelope dindependentl yfro mth eEuropea ntechnolog y whichrender si tal lth emor einteresting .However ,thing schange dcompletel y shortlyafte rtheMeij iRestoratio no f186 8an dagai nafte rWorl dWa r II.

Theyear s around 1600mar k aperio d of profound changes inth eJapans e political and economic system.Th esyste mwa s - andwoul d remaintil l 1868- afeuda l systemwit h daimyoo rbaron s governing their fiefswit h only anomina lvassalag eunde r theEmperor .I nth eabsenc eo f apowerfu l central government theclan s and lords ofcastle swer e fighting each other toconque r land and to increase theirpossessions .Th ecountr y was pacified in 1615b y twogeneral lissimos ,Hideoyosh i andTokugaw a Ieyasu(. +1616 )wh o succeeded inestablishin g acentra l power,th e so-calledTokugaw a Shögunatea tYed o (Tokyo)whil e theEmpero r continued toresid e atKyoto .Wherea s thedaimy o remained inpossessio no f their fiefs theywer en o longer allowed towag ewa r and theonl y posibility to increase their territorywoul db et ogai n lando nth esea .

Thedecisio n of theTokugaw a Shoguns toperpetuat eth emilitar y organization of thecountr y intime s ofpeace ,a sSanso mexpresse sit ,

- 264- entailed aneconomi c problemo f considerablemagnitude .Th e local economywit h payments,als oo ftaxes ,i nkin dha d tob e changed intoa monetary economy.Th e expenses of theShogun s and thedaimy ö increased rapidly inconsequenc eo f thecivi lwork s of the Shögunate,impact so f calamities,attendanc e at thecour t of theShögu na tYed oan d double luxurious livelihood inYed oan d in theirow nfief so n thepar t ofth e daimyo.Thu sbot hpartie swer e gradually driven toeconomi cstringency . Tocop ewit h the situationvariou smeasure swer e taken,on eo f these being thedevelopmen t ofne wland .

Inth esam e time ason e sees inHollan d agifte d builder ofwindmills , Leeghwater,i ncharg e of impolderingworks ,i nJapa na talentedma n appeared on theimpolderin g scene:Kat oKiyomasa .H ewa sno t originally anartisan ,lik eLeeghwater ,bu t adaimyo ,an dh e isknow ni nth e history of Japana sa genera lan d asa narchitec t of fortifiedcastles . Itwa sperhap s throughhi m that the traditional design of theJapanes e polderdike swa s developed consistingo f aston ewal lwit h astee p facing at theoutside ,a cla y fillan d another stoneretainin gwal la t the land side.I ti ssai d thath e started his engineering activities whenh ewa s stillyoun g and thath e supervised thework spersonall y spurringhi s favorite horse.Th eJapanes e engineers acquired aspecia l skill inbuildin gheav y stonewall s ona ver y softsubsoil .

A second important stimulus for theimpolderin gwa s thewa y inwhic h thework swer e carried out.Th edaimy o commandeered farmers tod o the work and- asa compensatio n- thene w landswer ehande d outamon g them when thework swer e completed.Whe n theland sbecam e productivemor e land-taxes could be collected and in thiswa ybot h partiesbenefitte d from theimpolderin gworks .Thu s- just like in theNetherland s -th e 17t hcentur y became apea k period of thehistor y of impoldering in Japan.I na later stage,whe nric eprice s jumped up,tida l land reclamationwa s alsoundertake nb y tradesme n although,i ngeneral , this typeo f investmentwa sno tconsidere d asa ver y attractive one owing toth eris k ofdestructio nb y thetyphoons .

In thesam eperiod ,i nFrance ,Kin g Henry IV (+ 1610), themos tpopula r king in thehistor y of France,succeede d inabou t thesam emanne r asth e

265 Shoguns inJapa n tohal t thewar sbetwee n thefeuda l lords,t ounif y the country anditoundertak eman y schemes of land reclamation including impolderingo fmarshes . TheMeij i restoration inJape n (1868)whic h changed thehistor y of the country evenmor e thanth eTokugaw a Shögunateo f 1615ha d alsoa profoun d effect onimpoldering ,especiall y on its technologicalaspects .I n 1870 agrou p ofDutc hengineer s including artisans sailed toJapa n towor k therefo r 10o r 20years .The y introduced thewester n technology inth e field ofhydrauli c engineeringwhic hwa s sot o speak super-imposed on thetraditiona l and indigenous technology.Mentio n shouldb emad e especially ofth eprojec t for theenclosur ean d partialreclamatio no f KojimaBa ynea rOkayama ,a schem e similar to thato f theZuiderzeework s inth eNetherland s which- at thattim e- ha dno tye t started.Th e enclosingda mo fKojim aBa ywa sno t completed before 1956bu t the polderswer ereclaime d earlier.

Unlike inth eNetherlands ,i nJapan ,i nth eyear s twenty and inth e thirtieso f thiscentury ,th epolitica lcondition swer eno t favourable for impoldering. Things changed completely afterWorl dWa r IIwhe n Japan sawitsel f confronted with a shortage of food and thenecessit y tofin d alivelihoo d forrepatriatin g farmers.Peacefu l conquest ofne w landfro mth ese awa s takenu p againan d contactswit h thewester n engineeringworl dre-established .

Twofact s ofhistorica l significance emerge from thispostwa r period. The first is thetechnica l feasibility of impoldering of landwhic hi s normally by severalmetre s under conditions ofheav y tropicalrainfall . Thesurviva l of thedee ppolder s created under thesecondition s depends on theprope r functioning of theprotectio ndik ean d thepumpin g devices tokee pou t thesurroundin gwater s and todrai n off excesswate r fno m localrainfall .Wit h thedryin g up the lagoonHachiro-Gat a in 1966Japa n joined thegrou p ofcountrie swher e suchdee ppolder sha d beenreclaime d previously orcam e intoexistenc eb y subsidence:th eNetherlands ,Poland , Denmark,Indi a (Kerala State),U.S.A . (California)an dEgypt .

Thesecon d factrefer s toth eeconomi c justificationo f sophisticated polder projects.Accordin g toth e commonly usedmethod s ofeconomi c

- 266- evalutiona compariso n ismad ebetwee n thecost s and thebenefit so f theprojec tdiscounte d according toa n interestrat e to thepresent-da y values.Wit h thepresen thig hrate s of interest thismean s thatbenefit s obtained insa y 20 to2 5year s fromno wrepresen tver y littlemone y to-day.Howeve rmos t of thehydrauli cwork s of apolde r likeembankments , canals and sluices areservin g forman yhundred s ofyears .Bu t inth e standard economic evalution itdoe s notmak ean y differencewhethe r after 20o r 25year s thesework swoul d stillexis t ornot .Thi s isa parado x indicating, that thecommonl y usedmethod s of economic evalutionar e not suitable forproject s like irrigation,drainag e and impoldering. Theyma yb eappropriat e forappraisin g industrial investmentswher e machines dobecom e absoleteafte r such ashor tperio d oftime .

All largescal eimpolderin g projects,carrie d outdurin g thepas tdecade s in countries likeBangladesh ,th eNetherland s and Japan,ar eno t economically feasible according thestandar d criteria ofbenefit-cos t ratio.Ye t their implementation and financingwer e decided uponb y the governments concernedbecaus eo f theirsignificanc e forth efutur eo f thecountry .

4. Analysis of thehistor y of impoldering

Thestud y of thehistor y ofimpolderin g inth eNetherland s andJapa n has produced awealt h ofhistori c facts and someconsideratio no f factors thathav ebee n determinant intha thistory .Thes efactor s orvariable s areo fvariou s nature:technical ,economic ,social ,politica l and psychological.Thi s leads toth econclusio n that thishistor yha sbee n a complexmatter ,a fac twhic h also applies toothe r fields ofhistory .

Recently theFrenc h geographerBethemon tmad e aclassificatio n ofthes e variables asa napproac h toa ne w theory onth egeneratin g factorso f irrigation,drainag e and flood control.Sinc e thesam efactor smus thav e been active inth ehistor y of impolderinghi s study,presente d inth e framework ofth e I.C.I.D.-projectmentione d earlier,i so fparticula r relevance.

Bethemont classifies the"independen t variables"i nthre emai ngroups ,

267 viz.: theincitement s fora change ,th eexistenc e of favourable"vectors " and asociet ywhic h is favourable and receptive tochanges .H e considers thesevariable s asnecessar ybu tno t sufficient forth e "genesiso f hydraulicenvironments" .

Theincitement s comprise factors already encountered inth e analysis of thehistor y of impoldering inth eNetherland s andJapa n suchas : population increase,economi cperspective s andcrisi s and changes inth e natural environmentbu t also factors likesuccessio n ofdr yyear s and cultural aspirations.Som eo f theincitement s canb e indicated asth e "challengean dresponse "group .

Under thevector s appearth etechnologica l stimuli,als omentione d earlier,an d alsoth etraditiona l staple crops often associatedwit h various forms ofreligiou s cultes likewe t ricei nSout h EastAsi aan d mais inSout hAmerica .

Thesocieta l group comprises therequirement s of aminimu mo f stratificationan d coherence for theestablishmen t ofa n organization forth eimplementatio n andoperatio n ofhydrauli c schemes.Als oth e existence ofa clas so ftechnicians .H e concludes that at acertai nstag e of spatial development and technical evolutionth eessentia l element in thedevelopmen t ofhydrauli c environments isth eexistenc eo fstron g social structures capablet o imposetechnica l constraints liketh e collectivemanagemen t ofth esystem s and also toassum ea join t defence of thereclaime darea .

Thewor k ofBethemon t represents animportan t step inth e integration ofth ehistor y of irrigation,drainag e and flood control into thegenera l history ofmankind .

There ison egrou p ofincitement swhic hha s played aparticularl y relevant role inth ehistor y of impoldering. It isth egrou p related tochalleng ean d response.Polder s along certain seacoast s and certain rivers arever yvulnerabl e andnatura l disasters causedb y storm surges atse a and river floods are likely tooccur .Wha twil lb eth e responseo fma n andwha t factors determine that response?

268- There isa psychologica l aspecto f that questiona swel l asa technica l point.Ma n isnaturall y inclined to forget about disasters and factual experience oni t isonl y toa smal lexten t transferable fromon e generation to thenex t one.Bu tnatur egive sn o respitean d sooneran d laterth eblo w comes,ma nwake s up and,wit h theide ai nmin d thati t shouldneve rhappe nagain ,ask shimsel fwha t tod oagains t it.Whethe r thiswil lb e followedb y anactua l andvigorou s responsedepend so nhi s technical capabilities and financial possibilities.Th etechnica l aspect ofth echalleng ean drespons esituatio n istha t experienceha sshown , that inth e fight against theflood s acounter-offensiv e ismor e effectivetha na restoratio no fth estatu s quo.Ther ewil lalway sb e higher floods thanbefore ,highe r requirements withrespec t tosafet y andwate r control,th eembankment shav eentaile dhighe r floodlevels , riverbed shav egon eup ,etc .Ne wline s ofdefenc ehav et ob e created tomak ehea d against theenem y inne wsituations .

A fewexample s ofrecen t disasters inpolde r areaswil l showth e significance of challenge responsefactors .

Onth efirs t ofFebruar y 1953th esouthwester npar t of theNetherland s washi tb y astor msurge .Th ese aleve lros et o levelshighe r thaneve r recordedbefor e and inten so fplace s these adike swer ebreached . Nearly 2000peopl elos t theirlive s and considerable damagewa s inflicted toth eeconomy .Th erespons ewa s acounte roffensive ,know n asth eDelt aWorks ,an d consisting ofa closur eo fth etida l estuaries by dams.

Shortly later,o nSeptembe r 26,195 9Japa n suffered from aserev e typhoon,th eIs eBa y typhoon,whic hhi t anare anea rNagoy aan d caused floodingo fman y polders.Th enumbe ro fcasualtie s andth eamoun to f damagewer eservera l times larger than thoseo f the 1963-disaster inth e Netherlands.Th evigorou s responsewa s thesam e as inth eNetherlands : damming offo f estuaries notonl ynea rNagoy abu t also inothe rplace s inJapan .

Still someyear s later,o nNovembe r 11th,197 0Banglades h washi tb ya cycloneo nth eBa y ofBengal .Th emaximu m sea level exceeded thecres t

269 levelo f thevulnerabl e "bunds"b y severalmetres .Th e resultwa s a terrible calamity,perhap s thewors tnatura l disaster inth ehistor yo f mankindwit hmor etha n 500,000 casualties.I tpasse dby ,almos t unnoticed, inth eoute rworld .Th erespons e of thecountr ywa swea k andmor e passive thanoffensive .A numbe r of "kilas"wa sbuil t similart oth edwellin g mounds inth eNetherland s erectedmor e than two thousandyear s earlier. The response inth ecas eo fBanglades hwa swea kbecaus eo f thever y tensepolitica l situation in 1970an d thever y poor economicconditions .

5. Prospects of impoldering inth eworl d

With theanalysi s just presented somefactor swhic hwil lb e determinant inth efutur eca nb e indicated. Ona shor tter mth eprospect s inth e Netherlands and inJapa n dono t lookver ybright . Inbot h countries there isn o shortageo f food;cereal s andmea t canb e imported atlo w prices fromth eAmericas .I nJapan ,wher ether e isno w asurplu so f rice,reclamatio no ftida l land is continuingno t foragricultura lbu t forindustria l purposes,applyin g themetho d ofhydrauli c fill.I nth e Netherlands theproces s ofdecisio n onfurthe r impolderingha sbee n paralysed,lik e inothe rsector s ofhe rsociety .

Elsewhere inthi sworl d conditions are entirely different.Th eonl ywa y to relieveth efoo d situationo fpovert y stricken countries like Bangladesh andWes t Bengal ist o improveth ewate rmanagemen t inth e existing polders andt otransfor mothe r upland areas intopolder swit h completeo rpartia lwate r control.Wha t applies toth edelt ao fth e Ganges also applies toman y other largedelta s and otherprospectiv e polder areas of theThir dWorld .Hig h costs of construction,deficien t methods of economic evaluationneglectin gbenefit s toth enationa l economy and lowprice s ofcereal s act for the timebein g asnegativ e incitementsbu thistor y shows that things can change rapidly.

There ison efor mo f impoldering inquit e afe wo f thedelta s andothe r low-lying areaswhic hha sme t aconsiderabl e success even from thepoin t ofvie wo fprivat e economy. It isth ereclamatio n of smallpolder s in thevicinit y of largecitie s for thepurpos eo f supply ofvegetable s and fruits. Cities likeBangkok ,Calcutta ,Saigon ,Jakarta ,etc .offe ra

- 270 ready consumingmarke t for theseproduct swhic h canonl yb e grown in polders inth eimmediat evicinit ywit h aperfec twate r controlan d flood protection.

Inth eopinio no f theautho r also large-scaleimpolderin gwil lb etake n upagai nbecaus eo f thenecessit y to increase foodproductio nan d the considerationtha t as long asma nwil lb eo n earth thesam efactor s that wereactin g inth epas twil l alsodetermin e ourfuture .

Thehop e isexpresse d that thisSymposiu mha smad e acontributio n toth e transfero ftechnolog y inth efiel d of impoldering.

271 6. References

1. History oftida l land reclamation carried outb y theHig oClan . ToshisaneShibuya . KumamotaYear-Boo k (1954edition) . Translated by theMinistr y ofAgricultur e andForestry ,Japan .

2. Deagrarisch egeschiedeni s vanWest-Europ a500-1850 . Bernard Slicherva nBath . Het Spectrum,Antwerpen ,1960 .

3. Irrigation inth eworl d -Comparativ edevelopments . HitsohiFukuda . University ofToky o Press,Toky o 1976.

4. Ricei nAsia . TheAssociatio n ofJapanes eAgricultura l ScientificSociets . University ofToky oPress ,Toky o 1975.

5. Sur lesorignie s del'agricultur ehydraulique . JacquesBethemont . XleCongrè s I.C.I.D.Grenobl e 1981.

6. Land development and improvement projects inJapan . ShiroSasaki . Agricultural Development Series 3.Agriculture ,Forestr y and Fisheries Productivity Conference,Toky o1959 .

7. Dredge,Drain ,Reclai m- Th ear t of anation . Joh.va nVeen . Martinus Nijhoff,Th eHagu e 1948.

8. Landbelo w sea level _ Holland init sag e- long fight against thewaters . Joh.va nVeen . N.V. Drukkerij Trio, The Hague 1953.

9. History of Hydrology. Asi t K. Biswas. North-Holland Publishing Company, Amsterdam 1970.

272 - 10.Histor y ofHydraulics . HunterRous e and SimonInce . DoverPublications ,New-Yor k 1957. li.A histor y ofDams . NormanSmith . PeterDavies ,Londo n1971 .

12.Japa n- A short culturalhistory . SirGeorg eB .Sansom . TheCresse tPres sLondo n1952 .

273 274 POLDERS OFTH EFUTUR E Prof. dr. ir.B .Verhoeve n International Courseso nHydrauli c and Environmental Engineering Delft,Th eNetherland s

Most of thelarge r terrestrialmammal s don't livefa rfro msom esourc e of freshwater .Ma n didno t forma nexceptio n tothi s general rule.A s amatte ro f fact,h e cannowaday s pumpwate r over longdistance s tohi s dwelling places.Nomadi c tribesmove d about,eac h time thewate r ran short around theirquarter s and they still continuet od oso .However , afterhavin g collected food fora fe wmillio nyears ,ma nwa sboun d to becomea mor e or less sedentarybein g fromth ever ymomen t thath e started topractic e crop growing. Indeed,som e cropgrower s remained semi-nomads,e.g . roamingabou t during theperio dbetwee n sowingan d harvesting,bu tmos t farmers settled downan dbecam ehighl y dependent uponsource sprovidin g freshwate r throughout theyear .I t isobviou s that thelowland s offered excellent opportunities forsupplyin g the people,thei r domestic animals and their cropswit hwater .

Indeed somepeopl e even succeeded increatin g living conditions farawa y fromope nwater ,b y digging deepwell s (Northern Sahara),collectin g water in tanks onmountai n slopes (SriLanka )o rb y transporting seepage water from thefoothill s through subterraneous passages of considerable length tothei r fields (Iran).However ,thos ewh o lived inth elowland s had easiest access towater .Goo d soils and excellent fishing andhuntin g groundswer eusuall yfoun di nthes earea s. Moreove rth etraffi cb yboa twa s fareasie r thanmovin g onba d oralmos tnon-existen t tracks.W efound , forexample ,tha t theforme rZuiderze ewa s at thattim emor ea lin ktha n abarrie rbetwee n thetown s andvillage s onbot h sides of thebay . Finallywate r- inparticula r rivers -wa s always awidel yuse d

275- receptaclefo ral lkind s ofwastes .No t thatwast edisposa l formeda majorproble mi nthos eol d days.

Oneparticula r disadvantage ispeculia r tomos t lowlands:th ewate r table canfluctuat e considerably.Th ewater ,howeve r essential itma y be,become s adange rwhe n itrise s too fasto r toohigh .Th e inhabitants of thealluvia l plains adapted theirwa y of lifet o this- usuall y seasonal- danger .The ybuil t theirdwelling s just outsideth evalley s onth eupland ,o nhig h riverbanks ,o nprotrudin g outcrops ofolde r stratao rthe y simply left thelowland s during theperiod eo f flood hazard.The y constructed dikes toguid e thewate r safely todownstrea m river tracts,buil t theirhouse s onpole s and evenpile d up eartht o makedwellin gmound s ("terpen"); smallone s forsolitar y farms andhug e ones forcomplet evillages .The yha dboat s athan d and locally theymad e raised roads oreve n footbridges to interconnect thevillage s andhamlet s inthos eperiod swhe n thelan dwa s flooded. In largepart s of theworl d comparable situations stillexist .

Assuming that thehouse swer emor eo r less freefro mdee pflooding ,i t nevertheless remained troublesome thatth efield swer eou to fus edurin g thefloodin g period.Eve nmor edetrimenta lwer e thebrackis h and sometimes salineflooding s inth edownstrea mpar t ofdeltai c plains.Har mwa s also causedb y thefac t that theflood s didno t comeever yyea r atth esam e time.Lat e floods could postponeth esowin g time and early floods could destroy thestandin g crop.Th e farmers tried asbes t as they couldt o adapt their agricultural practices toth erisks .Th eforegoin g sentences havebee nwritte n inth epas t tense,bu t oncemore :th estatement smad e arestil lhar d reality forman ymillion s ofpeople .

Ladies andGentlemen . Inth esecon d orthir d century asmal ldik ewa s built on theter po fFedderse n (Weserland,Germany) . Itprotecte d one house.W edon' tkno wwhethe r thiswa s thefirs tpolder ,bu t iswa sn o doubt an early one.Graduall y more lowdike swer econstructe d toprotec t small family terpen and thehouse s onthe man d sometimes alsopar to f theadjacent ,ofte n relatively high,land .Al l these dikeswer e small andver y local structuresbecaus e only thesmalles t communities showed enough coherence toenabl e concerted dikebuildin g activity.Th e

276- co-operationneede d fordealin gwit h largerdik eproject swa s foundno t earlier than 6t o7 centurie s after thefirs tsmal l dikecam e intobeing . However,th eLe xFrisonu mdoe sno t containan ymentio n ofdike s inth e year800 .I tma yb e that thelo wdensit y of thecoasta l population during thepost-Roma n transgression and thesocia l changes during themigratio n of thenation s caused thestunte d development ofdik ebuilding .Som e think thatth elon g and fiercefight s against therepeatedl y invading Vikings unified thefreedom-lovin gFriesian sbu tmayb ethi s isonl ya war-glorifying conception. Whatever thecas ema ybe ,i twa s only in thetent h century that abette r cooperation enabled themt otackl eth e hugejo b ofprotectin g largefields ,unti l then liable to flooding,b y means ofdikes .I ttoo k indeed another twoo r three centuriesbefor e the"golde n rings"surrounde d thewhol eo f the lowlands.Ye t localpeopl e still didno t placeto omuc h confidence inth eresult s of theircommo n work;fo ranothe r 100year s theycontinue d theheigtenin g ofth e"terpen" . Anyway,fro mth een do fth e 10thcentury ,th ewhol e cultivated lowland ofBelgium ,th eNetherland s andGerman ywa s embankedwithi n afe w centuries,thank s toth eincredibl e zealan dperseveranc eo fth e inhabitants.

Obviously,th estron g co-operationneede d forth ebuildin g of thelarge r dikes also applied toth estron g changes insocia l structure.Th esmal l farming communities lost influence infavou ro fvillag e andparis h organizationswit h theirmor enumerou smemberships .However ,smal lunit s still existed locally till fari nth e 18th century, (guaranteeing),fo r example,mutua lhel p incas eo f fireo rfunerals .

Inorde rt oachiev e anefficien t large-scale defenceagains t thesea , rulesha d tob e drawnu p and accepted by thepopulation .Th ebuildin g of thedike swa s acollectiv e activity of awell-structure d society of freepeople .Th ewor kwas ,a sa rule ,organize d byparishes . Monasteries and,late ron ,polde rboards ,als o tookpar t indik e building,th elatte rusin g hired labour oreve n contractors.Initiall y themaintenanc e andsmal l repairswer e thedut y of thelandowners .The y could shift off thisburde n toth etenants ,bu t theykep t theeventua l responsibility forth eupkee p of thedike . Majorrepair swer e thetas ko f thepolde rboards ,whic h inth eeven to f

- 277 calamities could evenge thel p fromneighbourin gpolders .I ncas eo f emergency everyonewa sboun d topersona l participation inth edikewor k and inman y places thenobilit ywa sno t exempted fromthi sduty .Th e importance ofdikewor kwa s recognized;bein goccupie db y strengthening a dikewa s oneo f thefe wvali d reasons forno t appearing incourt ,fo r example.

Arrangementsha d tob emad e forth e financial contribution of those farmerswh ower e less endangeredb y floodingbecaus ethe ywer e living farfro mth ese ao ro nhighe r tracts of land.Th emaintenanc e ofdrainag e ditches and canalsha d tob eorganized . Ittoo k centuriesbefor ewell - considered rules liketh eRustringe r ruleswer erecorde d andpolde r boards withwell-define d taskswer e functioning.Afte r thatth erule s had tob e adapted timeafte r tone wsocia l and technicaldevelopments . Sometimes social abuses crept in,especiall ywhe n thepolde rboard s became aclose d group and incapable and corruptboar dmember s inherited thechair s fromthei rfathers .

Attention isalway s paid toth elate rperiod s duringwhic h thecultivate d landwa s extendedb y embankment ofvegetate d coastal accretions andb y pumpingdr y lakes.Moreover ,pea tarea sha d tob e impolderedbecaus e they reached alo wleve l duet o subsidence,whic h intur nresulte d from thecultivatio no f thepeat .Technica l skills andmean s developed: windmillswit h revolving caps,steam-drive npumpin g stations fuelledb y coal orpea tand ,late ron ,diese l engines and electromotors assource s ofpower .

Spadesbecam e replacedb y draglines,bulldozer s and dredgers.Manua l transportwa s supersededby ,i nsuccession ,hors e and cart,narro w gauge railways and trucks.Tida l creeks indik esite swer e successively closedb y afas t supply of clay,b y sinking ashi p inth egap ,b y a simultaneous lowering of aro wo fslidin gpanel s and evenb y using caissons.Du e toal lthi s technical firework,w e easily forgettha tth e latergrowt h of thelowlan d plainsb yne wembankment swa sb y farles s than theare awhic h theol d coastal peopleha d protected sot osa y in onego ,b ybuildin g the"golde n rings"a sthe y called theselon g encircling dikes.W eten d to forgettha tbetwee n thefirs t primitive

- 278 dikean d theful lprotectio no f the- b y gravity drained -lands , nearly 1200year s passed away,wherea s thelas t centuries of thisperio d shouldb e seena sa mos t instructive epochbecaus emos t of thedike - buildingwa s concentrated inthos e ages. Itwa s during thesefe w hundreds ofyear s that,afte ra prolonge d and slowstart ,a changin g societywen twit h agrowin g collaborationbetwee n the lowlandpeople , which co-operation enabled thebeginning , theexecutio nan d the completion of such agiganti cwor kwit h suchprimitiv emeans ;eve nth e wheelbarrowha dno tye tbee ninvented. 'A s amatte r of fact,th elate r developments ofpolder san d poldermanagemen t forma nindispensabl e basis for thoughts onpolder s of the future inEurope ,bu tw ewil lse e hereafter thatpolder so f thefutur ear eessentiall y amatte r for the thirdworl d and for thatreaso nw ehav e tokee p inmin d thesever y early dayso fpolde rhistory .

Coming tothi s future,tw omor eo r less inter-related basic questions are:wher eca n thepolder s of the futureb e expected andwha twil l they look like? Inth efirs tplace :th epresen tpolder swil lfor m anon-negligibl e part of futurepolders .W eassum e that lossesdu e toearthquakes , stormsurges, landslides etc,etc .wil lb ever y smallan d thatnuclea r weaponswil lb eabolishe d before theywip eou tsuc hvulnerabl e items aspolders .I nfact ,existin gpolder swil lb emodernized .Fo rexample , thepowe r usually needed forkeepin g poldersdr ywil lb eprovided ,a t leasti npart ,b ywin d energy.Studie s of thispossibilit yhav ealread y shownpromisin g results.Mayb eothe r renewable,source so f energy canb e considered too.I nindustrialize d regions inparticula r improved control of irrigationwate r qualitywil l lead toe.g . theus eo f seepagewate r or eventh econstructio n of storagereservoir s for seepagean d precipitationwate r inorde r toreduc e theintak e ofpollute d river water. Thecontro l ofaquati can d bankvegetatio nwil lhav ebee n improved by the introduction of adjustedditc hprofile s and appropriate mowing rules,b ymor e carefulhandlin g offertilizer s andb y stocking thecanal swit hherbivorou sfishes .

But enough about thefutur e of theol dpolders .Mor e interesting are thene w ones.Wher eca nw e expect them?Hardl y anywhere herei n

279 North-Western Europe. Onmos tplace s thegrowt h of coastalaccretion s stoppedbecaus e theproces s of sedimentation came toa nand .Moreove r thesal tmarshe s thatwer e stillpresen t about 40year s agohav ebee n embanked for thegreate rpart .However ,th evi s inertiaeals orule s here. There arestil lpower s active toge tcoasta l foreland (including low-lying sand-an dmudflats )embanked ,usin g alleged arguments asnee d for improved defenceagains t thesea ,bette rdrainag e of thehinterland , creation ofharbou ran d industrial sites,extensio n ofrecreationa l facilities andwildlif e sanctuaries and eventh elac k offarmland .Bu t heightening of thedike sprovide s therequire d safety aswell ;upstrea m storagewil ldecreas edrainag eproblems ,th egrowt h of industry stagnates andmoreove r somemoder n industries don'tas k for asit enea r deep shipping channels.I na densel ypopulate d regio thedevelopmen to f newrecreationa l facilities ina natur eare ausuall ymean s the losso f existing,mor edistinguished ,form so frecreatio n (likesailing) .An d itseem shypocritica l toloo kfo rne wfarmlan d whengovernmenta l policy is todecreas e thenumbe r of existing farms asquickl y aspossible .

However,th emos tdecisiv e objection tone wpolder s camefro mth e biologists.The ywer eabl e todemonstrat e that thehig h ecologicalvalu e of this foreland-outweighed theadvantage s ofmakin g evenmino r changes inth epresen t status.Th esam ehold s formos t of the scarce lakesan d swamps thatcoul d be considered for impoldering.

Nevertheless,th e futurewil lbrin gplent y ofne wpolders ,no there ,, but in the thirdworl dwher e theyar ebadl y needed for raising thefoo d productionan dwhere ,afte r all,vas t areas areawaitin gbette rwate r managementsystems .

Actually,som epeopl e say thatfo r thetim ebein g norea lfoo d shortage had toexist ;tha thunge r ismor e amatte r of poverty than of atoo-lo w level offoo d production and thatbanishin gmalnutritio n andunder ­ nourishment is apolitica l issue thana technical problem.Whateve r the casema ybe ,a stron g increase infoo d supplywil lb eneede d inth e near futureanyway ,i nvie wo f the continuing increase inworl d population.Th ephenomeno n of large families fadesver y slowly.I n

- 280 order toincreas e thesuppl y of food,variou smean s canb e considered suchas :cuttin g downharves tan d storage losses,replacin g industrial and fodder crops by food crops,increasin gyield spe runi t of cultivated land and cultivating new land.

Limiting losses could indeed increase substantially thequantit yo f food available;substitutio n ofnon-foo d crops cana t least locally be of some importance too,bu tbot h subjects arebeyon d the scopeo f this symposium. Indensel y populated regions,th ebringin g under cultivation ofvirgi n land is less influential.Larg e tractsar e unsuitable for any formo f agriculture orhav e tob epreserve d inthei r present statefo r somereaso n orothe r (e.g.forests) .Moreover ,th e possible extension of cultivated landb y impoldering inorde r to increasefoo dproduction ,form s onlya mino r track.

Even thisnarro w path isofte n ineffective either because thesoil s prove tob e of aninferio r quality,th edikin g isto oexpensiv e oreve n because the scarce localpopulatio nmake s thebes tus eo f thenatura l environment and cannotb eremove d since they attaina reasonable standard of living.However ,th emos t seriousobjectio n to impoldering is that thesewetland s in theirnatura l stateiofte nprov e tob eto o valuable in the long term toth esurviva l ofmankin d tob ebrough t under cultivation. Fortunately there stillremain s oneothe rmetho d of increasing food production:raisin gyield s perhectare .An d inthi sapproac h impoldering plays an,importan t part.I nsom eregion s it is- a t leastfo r thetim e being- no t evennecessar y toreclai mvirgi n landbecaus emillion so f hectares of cultivated land areawaitin g impoldering.Her ew estil l find conditions comparablewit h thesituatio n in theNetherland s one millennium ago.Th epeopl e live onhighe r spots ino rnea r thelowlands , but theirfiel d areno t protected against flooding,hav e onlyver y simpledrainag e facilities andyield s areprecarious . Insuc h areasa betterwate rmanagemen t isa prerequisit e for the introductiono f moderncro pvarietie s doubleric e cropping and otherne wcro p rotations,a mor eadvance d use of fertilizersan dpesticides . Yields canb e increased substantially and overvas tareas .Her e the polders of thefutur ewil lb e established.

281 Aproble mma yb e thatfo rpolitician s thegainin go fne w landofte n seemsmor erewardin g and less troublesome than theimprovemen to f existing agricultural land. Theregion s of thene w poldersbein g assessed,ther estil lremain s the questionho w topla n theman d how tege t them constructed? Reclaiming new landmean s the irreversible elimination of oneo rmor ebiotopes , butimpolderin g cultivated land isals oa radica lmeasure .I tmean s thedefinit e terminationo fa geologica l development,becaus e itstop s sedimentation. Impolderingha shydrologica l consequences,suc h asris e of flood levels inth eriver .I tha s- even inth ecas eo fcultivate d land- astron g influenceo n floraan d faunaand ,a sa rule ,societ y changes. It ismoreove rver y costly.Th epossibl e changeshav et ob e studiedbeforehand ,bu t predictions aboutwha twil lhappe n areofte n difficult,i nparticula rwit h respect tosocia ldevelopments . As amatte ro f fact largebu t flexibleoveral l schemes areusuall y indispensable,bu t aslew ,ste pb y stepexecutio no fsuc h aschem ei s preferables otha teac h smallprojec t canserv ea s atechnica l and social experience forth enex tone .

Iti sno tnecessar y andmayb eno t evenwise ,t ostar twit h onesmal l dikeprotectin g onehous eonl y- a s inth ecas eo fth eter po fFedderse n 1800year s ago- an di t isno tpossible ,i nvie wo fth e food scarcity, totak esevera lhundred s ofyear s as theol dFriesian s didbefor eth e land isproperl y protected.Bu t itmus tb eclea rwhethe r land users are ablet eorganiz e inon ewa y oranothe rth emaintenanc e ofdikes , structures and canals of at least asmal lpolde r andho w they cancop e with repairs.I tmus tb eknow nwhethe r thefarmer swil lmatc h agricultural practiceswit h thene whydrologica l situation. Itha s tob e studied whether theeffec t ofth ene w polderwil lb esuc h that the rich landowners become richer andth esmal l tenantsbecom e landless and unemployed labourers. Ingenera l social commotion isno t aphenomeno n thatneed s development.

Until ashor twhil e ago,impolderin gwa s easy:mak ea ringdike ,a sfa r aspossibl eo na leve l orothe r stripo fhighlyin g land,choos e asit e farupstrea m for an intake structure,buil d adrainag e deviceo na downstream spot,la y downsom e canals and roads and that isthat .

282 Nowadaysw e oftenconside r itbette rno t tostar twit h thetota l elimination ofth efloods ,bu twit h aregulatio n of thetim ean drat e of flooding.T obegi nwith ,th ehighe rpart s ofth eare a liablet o flooding canb eprotected . Forth ewate rmanagemen t ofth elowe rparts , different courses canb epursue d depending onth eheigh t ofth eland . Among thesecourse s canb e included thelowerin g ofth esurfac einflo w fromth ehighe r partsb y catch canals;controlle d floodingb y submersible dikes;accelerate d drainage;constructio no fstorag ebasins ,etc .etc .

Sucha differentiatio ni nintensit y ofwate r control requires various adapted formso flan d use,fishpond s etc.etc .I nth erive rdike s overflows canb e constructed sotha t incas eo fhig h river levels some water can flowof fthroug h depressions inth epolders .

Inth ecours eo fth eyear swate rmanagemen t canb e adjusted tochangin g demands ofagricultur ean d insom eplace s thedevelopmen t mag endwit h apolde r "Dutch style".I nothe r placesmayb eeveryon ewil l keephi s ownlittl e"polder" .Bu tno t only doeswate rmanagemen thav e tob esubtl e andmodern :ne wway s alsohav e tob e found forth eenerg ysupply . Attentionmus tb egive n totechnique s forproducin g energy forth epump s fromrenewabl eresources .Solution swil l differ fromplac e toplac ebu t low-head turbines,windmills ,motor s drivenb yburnin gbioga s orwaste s fromwoo d of formothe r agricultural products arei nus eo rwil lb ei n usesoon .

Maybeth egreates t advantageo f stepb y stepdevelopmen t of thewate r management ofexistin g agricultural areas istha t the farmers are themselves involved inth eestablishmen t of theproject s and thatthe y learnt ose t up awate rboar d forsmal lhydrologica l unitswit ha relatively simpletask . Inthi swa ybi g and expensive centralized organisations canb e avoided and thesmal lwate rboard s canserv eth e purposeo f increasingyield swithou t disturbing thesocia l structurean d thewell-bein g of theloca lpopulation .

Inshort :plent y ofwor k iswaitin g foral lthos ecivi l and agricultural engineers,sociologist s and ecologists,wh o aredealin g inon ewa yo r anotherwit h land andwate rmanagement .W eurgentl ynee d sound flood

- 283- control,efficien t irrigation systems andadequat e drainage facilities, which all combinedma y lead topolders .An d thesepolder swil lmee t the requirements of thefuture .Requirement s related to aneconomi c useo f energy andwater ;t oth edevelopmen t ofa decen t society and the. preservationo fa health y environment. Requirements guaranteeing an existence forman y cominggeneration s ofplants ,animal san dhuma nbeings . Wewil lnee d allou r resourcefulness toreac h thisgoal . It istim ew e put ourmind s toth enex t symposium dedicated completely toth efutur e aspectso fvariou s types ofpolderlik eunit s onagricultura l land.

- 284 Literature

Early Implementation Projects forFloo d Control and Irrigationi n Bangladesh.Firs t interim report, 1978.Euroconsult ,Arnhem .

Glopper,R.J . de,Aspect s ofreclamatio nplans .Lan d andWate rIntern . 24, 6-13,1974 .

Grijm,W. ,Ma nan d Science inth eDevelopmen t ofWate rResources . Newsletter IHE,JJ3 ,22-26 ,1980 .

Horst,L. ,Alternativ eDevelopmen t Concepts inPotentia lPolde rArea s inDevelopin g Countries,1982 .Thi s symposium.

Liere,W.J .van ,Southeas t Asia- Potentia l World FoodBasket ,Neth . J.Agr .Sc . 25,14-25 ,1977 .

Odum,E.P .,Th erol eo f tidalmarshe s inestuarin e production.Th e Conservationist_L 5(6) ,12-15 ,1961 .

Ohling,J. , (ed).Ostfrieslan d inSchutz ede sDeiches .Krummhorn ,1969 .

Veen,J .van ,Dredge ,Drain ,Reclaim. -Th ear to fa nation .Th eHague , 1948.

Volker,A. ,Histor y and futureo f impoldering inth eworld , 1982.Thi s symposium.

285- - 286