OCEANOLOGICA ACTA 1986 VOL 9 - N 3

Comitb da Parrainaga - Board of Sponsors - Förderer-Komitee J. Aubouin (Paris) A. Favre (Marseille) R. Margalef (Barcelona) Hydrosedimentological processes ßdritoIndonesia esludry M. Bacescu (Bucarest) M. Fontaine (Pars! W. A. Nierenberg (La Jolla) :a-- Superficirl .;edimeiil J. E. Bardach (Hawaii) M. L. Furnestin (Marseille) J. Nihoul (LiBge) and soils Hydrodyn.imics B. Battaglia (Padova) A. Guilchar (Brest) J. M. Perds (Marseille) . soits J. Bergerard (Roscofl) C. Guillemin (Orleans) F. O. Por (Jerusalem) ' Indonisic R., Billard (Jouy.en-Josas) K. J. Hsu (Zurich) R. Reyment (Uppsala) of the Barito estuary Ertunire Barito G. Boillot (Paris) A. lvanolf (Paris) E. Seibold (Kiel) SMimenl superficiet L. M. Brekhovrkikh (Moscou) H. Lacombe (Paris) J. Thiede (Oslo) Hydrodynamique R. Chesselcl (Gd-sur.Yvette) C. LBvi (Paris) M. Vigneaux (Talence). (South , ) SOIS P. Drach (Banyuls-sur-Mer) R. Marumo (Tokyo) F. Webster (Washington) .. G. Dunoyer de Segonzac (Strasbourg) ,M. S. Longuet-Higgins (Cambridge) P. Willm (Rued-Malmaison) PII. BASSOULLET ', R. DJUWANSAH ', D. COWEAU ', C. NI&!!&.? M. Eyries (Paris) A. D. Mclntyre IAberdeen) ' Institut Franqais de Rechcrchc pour l'Exploitation de la Mer (IFREMER), Ccntre de Brest, B.P. 337, 29273 ~Brest,France. Comit6 Sciantifique - Scientific Board - Wissenschaftliches Komitee Lembaga Gcologi dan" I'eeitambangan Nasional (National Institute'of Geology and Mining), (Indonesian Institute of Sciences), Jalan Cisitu, Sangkuriang Pr6sident Chairman Vorstand LIP1 - - no 21!154 Bandung, Indonesia. H. J. Ceccaldi (Marseille) D. e UniversitC deCNantcs, Laboratoire de Géologie Marine, 2, rue de la Houssinikre, H. Chamley (Villeneuve d'Ascq) W. Ernst (Bremerhaven) L. Laubier (Paris) 44072 Nantes. France.

M. 8. Cita IMilano) J. Gonella (Paris) A. R. Longhurst ( Dailmouth) I' Université Louis Pasteur, Institut de Gkologic, I, rue Blcssig, 67084 Strasbourg, J. Dagel (Paris) A. Herbland (h,?i;is) A. L. Rice (Godalming) France. E. K. Duursma (Yerseke) P. Juhel (Brest) G. Siedler (Kiel) G. Eglinton (Bristol) C. LaIou (Gif-sur-Yvette) Secretaire de redaction Received 5/3/85. in revised fqrm 4/3;86. accepted 10/3/86. RBdactaur en chef - Chief Editor -'Chefredakteur Editorial secretary - Mitarbeiter der Redaktion Jacques Boutlei Brigitte Jelidi I ABSTRACT A pluridisciplinary study was carried out in the south-eastern part of Kalimantan Oceanologica Acta publie en lranqats. Oceanologica Acta publishes in French. Die Zeitschrift Oceanologica Acta verof- (Indonesia) in a deltaic area close to town. anglais ou allemand les resullats de travaux English or German the results of work in all fenrlichtin Französisch. Englischoder Deutsch Upstream from Banjarmasin, dividcs into two branches, one of which dans toutes les disciplines oceanographiques. sections of oceanography and from all parts o1 die Resultate von Forschungsarbeilen aus den relatifs B n'tmporle quel secteur des oceans. y the oceans and their adjacent estuaries and verschiedenen Fachgebieten der Meereskun- meets the slightly further to the west, to form the Kapuas Murung compris les estuaires et les eaux saumatres. brackish water systems. de. die die Ozeane. die Astuare und Brackkas- estuary. La revue accepte des manuscrits piesen- The journal will accept papers describing sergebiete behandeln. This programme is designed to increase knowledge about the physical and scdimentolo- lanl des resultats origLgaux. des courtes notes original results. short notes and reviews Oie Zeitschrift nimm1 Manuskripte mit et des svnlhtses The main requirement lor acceptance of a Originalbemagen. Kurzberichten und zusam- gical processes, physical and chemical properties of the soils, and hydrological and La qualite ScientIlique. Bvaluee par un Paper is its Scientific value as judged by an menfassenden oarslellunqenan. chemical parameters of the Barito estuary. arbitrage international. constitue le crilhre international refereeing system. Oie wissenschaftliche Oualital der Beiträ- Barito estuary was chosen for two main reasons. First, it constitutes an important maicur d'acceptation Manuscripts submitted should preferably ge bildet die wtchligsle Grundlage lbr eine Les manuscrits soumis doivent de prblb- have an inlerdlSclDlinanl character and be Of Annahme der Manuskripte und wird von einer waterway for the region, on which Balljarmasin harbour is located; second, the rence prOsenter un caractere interdisciplinaire. interest 10 more than one field of oceanogra- internationalen Gutachtergruppe geprüft. managemcnt of the sparsely occupicd coastal areas is becoming a priority. The c'est.e?-dire interesser plus d'un domaine de phy Die vorgelegten Manuskripte sollen I'ochanoqraphie II ne sera pas lait de distinc- No formal distinction Will be mde vorzugsweise interdisziplinär sein. d. h. transmigration arca of Tabunganen, close to the coast (with some saline intrusion lion formelle enlre lea resultals d'ordre between Papers describing fundamental 01 mehrere Sachgebiete der Meereskunde problems) is significant in this connection. fondamental ou d'ordre applique. Touteloisles applied work: however Pape15 Which report behandeln. Es kann sich um Ergebnisse The study, some results of which are presented here, is not complete; this is especially travaux ne doivent pas etre puiement descrip- excluslvelv applied or descuptlve work are leSS der Grundlagenforschung oderderangewand- 14s ni excluvvmwnt rnnlmj$c likely to be accepted. ten Forschung handeln. jedoch sollen die due to a lack of data during the rainy season. But its aim is to provide the basis for une pieleience sera dunnee aux alllCleS Preference will be given 10 Papers dealing Aufsätze weder rein deskriptiver noch rein any future complemcntary study. mellan1 en evidence les aspects quanlilallfs with quantttative aspects of phenomena and angewandter Art sein. des phenom$nesetudieset traduisanluneffort demonsiralmg a special elfort of synthesis or Der vonug wird solchen Beiträgen Oceanol. Acta, 1956. 9, 3, 217-226. particulier de ;ynthtse ou d'interpretalion. interpretation. gegeben. die die quantitativen Aspekte der Un,ellort particulier portera sur les delais Every eflorl will be made 10 publish as Untersuchten Vorgänge behandeln und insbe- de publicalion quicklv as possible sondere eine Interpretation und Sinthese Les processus hydroskdimentologiques et les sols de I'estuaire du Barito I.es manuscrtts ri la correspondance doivent Manuscripts and correspondence should be einschliessen. RÉSUMÉ etre adresses B Oceanologica Acta. 66. ave- sent to Oceanologica Acta.6lj. avenue d'lena. Besonderer Wert wird au1 die Veröllentli- (Sud Kalimantan, Indonésie) nue d'lena. 751 16 Paris 751 16 Parrs chungsfristen gelegt. Oie Manuskripte und die Korrespondenz Une etude pluridisciplinaire a été menée dans la partie sud-est de Kalimantan dans sind zu senden an Orsanologira Acta. 66. ave- une zone deltaïque proche de l'agglomération de Banjarmasin. nue d'lena. 751 16 Paris. En amont de cette ville, le fleuve Barito se sépare en deux bras dont l'un rejoint un IR Mqstnn Inf~~mrnwbwlto(ln I Inlnm"~~,S~wniai~uw vi Techniwe -IC Cenlre National de la Recherche Scienl8ltuue - fleuve légkrcment plus i l'ouest, Kapuas, pour constituer I'estuaire du Kapuas Murung. I insi~itjiFvnnca8r de RPC~~~~CIIBDOU, I'Exnlo!lalmn de la Mer i lnitm~Francais du Petrole - I'Olltce de la Recherche Sclenllllque el Technioue Olme Mm Ce programme a pour but de mieux connaitre les processus physiques et sédimentologi- ques. les propriétks physiques et chimiques des sols, les paramètres hydrologiques et . chimiques de l'estuaire du Barilo. Le choix de l'estuaire du Barito est principalement Abonnements 1987 -Subscriptions 1987- Abonnements 1987 ORsTOfvq fo!?ds "mtalre fondé sur deux raisons. Dune pert, il constitue un axe navigable important pour cette un an. 4 numeros One year. 4 issues ein Jahr. 4 Helfe région: axe sur lequel est situé le port de Banjarmasin. D'autre part. I'aménagement France 740 F - Pays etrangers - Foreiqn Countries - Ausland 935 FF de zones plus cötikres, trks peu occupées, devient prioritaire. No : 25888 L'implantation de la zone de transmigration de Tabunganen, proche de la eÖte (avec Rcmuse SDecaaie de 50 ". our ahonne. Oursaecial discount o1 50%lortndiv1dual Sonderrabalt 50% 1% Einzelabonnenten gk men& mdwduels B I'adiesse personnelle. subscription to a Drivate addressis ollered only an privaleAnschri1t.wenn Sie einer Organisa- les probli.mes d'intrusion saline qui y sont IiCs) est significative de ce fait. r6scrvPe aux Dersonnes physiques apDartenanl 10 individuals belongong to an organization tion angehören. die bereits abonniert ist. Bei Celte étude. dont quelques résultats sont présentés ici, n'est pas complkte; en particulier 2 un organtsme dela abonne. sur pstilicatton which has already its own subscriptlon. A der Bestellung bitte Bestätigung beilGgen. par le manque de données en saison des pluics. Mais elk a pour but de définir les de ceIui.ci lustilication o1 the above mentioned subs- criplion should be produced f 8 Ag6 2 bases pour toute étude complémentaire future. Ahortnemenls'SubscriolionsiAbonnements C O R -Centrale des Revues , q 'lCT, y2.G Oceoriol. Acm, 1986, 9, 3. 217-226. hdmin~slralinn'Publ~shlrlgOll~celVeiwdlr8~s I 11. rue Gossin. 92543 Montrouge Cedex. (France). Tel. 46-56-52-66 Envoi de soecimm graruil sur demande -Gratis sneclmen co~ysent on reouest-Gral6 Musterhell auf Anfrage -I ,~ ' Ph UASSOULLET PI al HYUHOSEOIMEN~OLOGYOF THE BARIFO ESTUARY .t -___ ,. INTRODUCTION i Transmigration Program, several canals have recently ' been built. of which the principal is Tabunganen. Barito Indonesian coast;il plains arc among the most densely delta is a,swampy delta. mainly reclaimed now for rice popiilittcd rcgioris of the globe. An iiicrcascd pace of cultivation. developmcnt is foreseeable in connection with plans to develop tidal irrigated rice fields. Clinlate As the co:istd zone is an arca of interaction between '2 Profil Br.8 lhe contincntal :ind ni;irinc cnvironmcnts, any change With an avcrage annual rainfiill of 2823 m at Banjarmasin. the region is characterized as having a in this zone might ;ifTccc both environments in a posi- tive or iiug:ilivc way. Within the fr:inicwork of Frcnch- "pcrliumid bioclimate" by Fontanel and Chantefort Intlonesien Coopcr;ition in Occenology. on tlie theme 11975). This bioclimate. which covers approximately "Coastal zoiics management, ßarito Research Pro- 20",, of the Indonesian Archipcl:igo, is marked by ahun- dant precipitation. although the annual total is lcss gram". il first piece of pluridisciplinary fieldwork. 12 Profil Br.6 involving mcasurcmcnts and s:iniplings. was carried out than JtXIO m. The rainfall is well distributed throughout tlie year and tlie monthly amount is mostly above in i\icgust 1983 by a tcain of French and Indonesian ,, Profil Br.5 sciclllists. I00 mm (Tab.). I-lowevcr some months may be suhhu- mid. for cxamplc in ßanjarniasin where August and A location map of thc study arca is presented in September receive lcss than 100 mm. The annual ave- Figures I and 2. The study of h~drosedimentologicnl rage temperature is 26.8 C. proccsscs covcrcd tlie Rarilo estuary from the Scrapat c:inal ( 15 km north of Banjarnm;isin) lo 5 km offshore C*oIogy from Tanjung I'cd;id;ituan and westwards up to a dis- 1:111ce of IO kin from the ßarito. According lo geological maps (Directorat Geologi N The soil survey covered the area hctween the Tamban Indonesia). the delta lies the southernmost part of a Profil Br.1 Canal to the north, the Barito River to the east, the largc Quaternary sediment along the southern coast of shoreline to the south and a line from Kuala Lupak Kalimantan. to Tamban Canal to the west. Almost all of tlie delta has remained up to the present Due to the poor quality of the geographical maps, only under the influence of tidal fluctuation. a reconnaissance was possible, although almost all the Along rivcrsides and crccks. the marine sediment is creeks arid canals were surveyed: 40 profiles were covered by fluviatile sediment which physiographically \ 1 observed and 130 samplcs were taken (Fig. 2). O. forms river levees and transforms the inner part into a Bkm Figure 2 IIItsrrr~iions: I) Achroslicum-Rhizophora ossocioliori: 2 and 4) Rhizophora: 3) Pandanus - Rhizophora - Melaleuca.

Table

Month J F M A M J J A s o N D, TOTAL'

Rainlall . -, *J

(mm) 436 298 323 269 206 156 156 98 70 141 273 397 f 2823 * 3 Number or days 21 18 18 I6 14 II IO 7 6 9 Il 22 169 !

and Rhiiophorn inticroitafa. Along the river and on the Species either of the mangrove forest or of swamp- 1 N. . Figure I shoreline. vegetation is mainly represented by Somera- forest are often associated with these species, and parti- Locaulinn mop qrfhc.SIIX/? nrm. fia caseolaris, species throwing out aerial roots like cularly with Achrosticto~i.The main associations obser- Localisation de la zone &ilude. A ciceirnia. ved arc: Achrosricir~~t-Rhi;opltora,Achrosticum-Nypa and Ac/irosric~o~t-M~/olcuca. NATURAL ENVIRONMENT marine sedimentary basin. The upper watershed of the Siranip Jorcsr Barito includes two prelcrtiary formations consisting The natural swamp forest is located near the Rhi- tiYDRoSEDIMENToLOGICAL PRoCESSES I of schists. grauwackes and sandstones in association zophora mangrove forest in Pisak besar river where Chgraphy -- ESTUARY with older eruptive rocks (peridotites, gabhros, granits. several spccics of swamp forest are concentrated inch- WIT'llN THE BA The shape of Ilic dell:~is almost quadrangular. bounded andcsits... 1. hy he parallcl ßarito and Kapuas Murung rivers which flow from to the Sea. These Vegetation (fig. 3) rivers are connected by Pulau Pefak river as the northern boundary (Fig. 2). Barilo river. 650 km in rC1orrgroce Jmst I'reskrvofer srvriritp estuaries and for the formation of deltaic complcxes. i length. is the most important of the One of tlie main products of this survey was the disco- These swamps occupy tile largest area of the delta The main processes acting on this particulate materia! rivers. very of a very beautiful Rhizophora forest with trees and are generally reclaimed for rice cultivation. Three (tidal current and river flow) were investigated. Two hig canals (Tamban and Scrapat) join Kapuas rising to more than 20 m above water level. Two species species are prcdominant: Achrosticunt ~W~IIIB.Hibiscus As is the case with most estuaries included within a Murung and Harito river. In the framework of the of Rhiz~~phorirare represenled: Rhiiopltora apiculata filiacrus and C~/~c~,s.~~~tifitdfi~. deltaic complex, Barito shows at its mouth on the

21 8 1 21 9 \

-'i I

' HASSOUI ET ,s/ dl HYDROSEOlMtNTOLOGY OF THE BARITO ESTUARY ,ch I *" ---- I .... . The diaproms [Fig. 4) show: o under spring tide and low water lcvel conditions, the ebb duration is twicc that of the flood. This .ra!io is obviously pronounced during the rainy scasok ' o for similar tidal cocfficicnts, the inlet vclocities (and notably cbb vclocitics) nt the BI station arc higher in rclation to the other stations. in Tact, tlic maximum of Ihc current vclocily distrihution is closely rclatcd to the 1opogr:ipliy. AI the inlet. water dcptli is low (5 to 6 m) conip:ircd wirh tlic cIi:inneI upstrewn from Baiijarmasin (more th:m 15 ni):

e :IS in most cstu;irics. ebb current velocities arc highcr t11:tn flood currcnt vclocitics. A point to bc nwJc hcrc is that whcrcas all thcse mcch;inisnis arc vcry well known in cstuarics with semi-diurnal tidc. there is vcry little Iitcrature dealing with diurn:il tidc estuerics. Currcnt vclocity iiicasurcmcnts along longitudinal pro- files within llic cstimry :it :I privileged moment of the tidal cyclc show :I morc pronounced wiitcr column stratification duriiig.,.ngnp tidc than during spring tide. This is duc to ii vcry pronounccd residual circulation and to vcry slight vcrtical iiiixiiigs during neap tide.

Hydrology

The Barito watcrshcd arca covcrs some J5,OM) km'; there :ire no data relative to Harito river discharge. We have thcrcforc attcinptcd to makc cstimations from average current vclocity mcasurcmcnts at rcprcsentative scctions of thc cstuiiry. upstrcam of the dynamical tidc. In the fieldwork. that estimation (realized during the 4 dry season) amounted to between 350-450 m3/s. AI each anchor stdon. with a sampling rhythm of 1.30 hour, 17 observations were madc at 3 levels: 0.50 m bclow the surfxc, mid-dcpth and 0.50 m from thc bottom. ts~~disnirw,vc. Java Sca ;in important accretion shoal which requires Their dynamic of suspcndcd matters. the mineralogy eauMesures moyenne. dec vitesses de cournnl durant des cycles de maree de vive frequent drcdging to maintain a correct navigation of thc suspcndcd scdinicnts and bottom scdinients. and Sidirii~jt1ii"xreiiieiifs cli:!nncl. l'lie prcsence of the SIIOQI. continuous silting the distribution of the latter within thc ßarito estuary and a very deep upstrcom chaiuicl confcr on the estuary aiid al thc rivcr mouth wcrc all analyscd. -At cach anchor stalion. during spring tide som specific Iiydro-sedimentological featurcs. The We present here successively the main results relating o Station BI: leli-nictre isobath reached between and 60 km is 20 to tlic hydrodynamics of the estuary, salinity and watcr During tlic tidal cyclc, at the surface, salinity is vcry On the bottom, watcr is frcsh for more than 1/3 of the from the coas1:11 line of the hlau Petak delta. Zones tempcraturc distribution, clicmical variations of tlic dis- reduced, ranging from 0.5 to 3.9. On the bottom, the tidal cyclc. in the process of erosion and accretion are dcscrihcd solved silica in watcrs and thc dynamics of suspcndcd sdinity varies from 1.3 to 31.7. Watcrs appcar to be o Station 83: hclow. matlcrs. vcry stratified (for cxamplc, s:ilinity incrcascs from 15 This station is locatcd slighlly landward from the chan- AS :I prcliiiiinary to tlic Iiydrcrdynnmic invcstigation of lo 27 bctwccn 3.0 in :ind 3.5 m bcncath the surlacc). the rktrito cstuary. two types of mcasurcmcnts wcrc nel linking ßanjarmasin to ßarito river in the main Thc minima and maxima do not corrcspoiid with low navigation channcl in front of Bmjnrmasin harbour. cnnductcd in August 198k Hydrodynamics nl the esluary tide and high tide ;IS wcll ;it thc surftice as at the &re. 65",, of thc tid:iI cycle IS represented by fresh and -- ;II :inchor st:itinns. in spring lide. to cslahlish velo- hottom. It is only :II mid-flood that bottom salinity brackish waters ( <5) on tlic whole watcr colqmn. city prol'ilcs on :I siiiiie wriiciil throughout a tidal cyclc Title r:ingcs along Ihc south coast of K;iliniantsn arc incrcsscs ngain (four hours artcr low tide). During instant:incous longitudinnl profilcs along the (24 Iiours): 0.50 :ind 2.80 III rcspcctivcly for ncap and spring tide cstiiary -- .II nine points distributcd tilong tlic estuary. in ordcr ni;isim:i. On this coast. the tide is miscd: diurne1 during o Stu1ion 132: -- tn ohtaili a synoptic;il piclurc of llic csluary in ils spring lidcs ;ind scmi-tliurn;il with vcry pronounccd AI this station. locatcd I5 km landward from ßl sta- The(Fig. longitudinal2) show: prvfilcs c:irricd out during neap tide cnlircly i11 ;I privilcgcd mniiicnt of the tide. incqu:ilily during nc:ili tides Iwith sccondnry high and tion. mcnsurcmcnts wcrc madc ii few days after a 'l'lic m;iin hydrnlogical p:iramctcrs studicd arc: tempe- low tidCS). lashing rain on rhc uppcr watcrshcd. Thc watcrs arc o that tlic uppcr limit on thc bottom of salinities highcr r:iIurc. s:ilinity. pH. clissolvcd oxygen. dissolvcd major A si1u;ilion map of the :inchor slations (U1 lo 03) and thus much lcss sallcd. than 5 is situatcd in waters between ßR5 and BR6 cnnslitucnts ;irid tlicir clicmicd variations in watcrs sampling points is prcscnted in Figure 3 with bathymc- AI the surf;icc. watcr is priictically fresh, with salinity (25 km from inlct) at low tidc and bctwccn ßR6 and (I3;lbscrullcl. 1084. try of nine cross scctions. r;ingin_r from 0.02 to 0.20 during 2j3 of the tidal cycle. BR7 (30 km from inlet1 ;it hlgh tide;

+.. 220 221 * Ph QASSOULLET er d/ IiYDROSEDIMCIUTOLOGY OF THE ßARITO ESTUARY J..- e' 'I: -<

that stratification is pronounced during neap tide: Tmiprrurirre cilriarions s;ilinity values are'lcss than 5 at the surPace and higher Only the distribution of temperatures within [lie estuary than 30.6 kni from the inlet at low water slack tide. according to a tidal spring tide cycle (from the three During spring tide. homogcnization is much more pro- stations data) is prcscnted here (Fig. 7). nounccd and the landward advance of the isohalines is This figure calls for SCVC~J~remarks: more reduced. Barito estuary is continually homogeneous in tempe- 't\Iong lhe external transects rature near the 02 location. Here it is slightly stratified Four transects of five kilometres ~acli(Fig. 2) were for three to four hours at tlie beginning or ebb (lempe- studied during neap tidc for salinity distribution at rature diffcrences surfacc/bottom in the region of one the river mouth and on each side of the Barito inlet ccntigrade degree). (Fig. 51. Temperature stratification of the estuary takes place exclusively at the beginning of ebb (mainly at the 03 location) during a period of about four hours. All the observations were made during a relatively low discharge of the river in a spring tide period. According to the drifts in tlie Barito estuary and the .." tcnipcraturc study. wc can obviously dctermine thrce water types: / - from marine drifts. with tcmperaturcs less than 2s c. - from river drifts, with temperatures between 29'C and 30c, - from channel drifts ("anjirs" and "handils", e.g. the ) with temperatures between 30°C and 32 c.

Stttc/.r ujche dissoliad silico uoriatiotls iii che wufers

Figure 5 Analyses concern 193 water samples. The diagram Sdinïtks (II thu inlrr. End ,!f~l,~~dduring nenp lide. (Fig. 8) presents the variations of dissolved silica with Xtewres des saliniles d I'enlbuuchurc en lin de flui par mark de chlorosity. Average contents are about 140 pmol/l for morte rilu. fresh waters to Il pmol/l for sea water (squarcd corre- lation coefficient of 0.97 for the equation of the dilution 01 ..., ...I... . I.. ..- straight line). O 10 20 The evolution of the bathymetry in thc arca is as In fresh and slightly brackish waters, the numerous C1'(%.) follows: low variations in silica concentration (between 120 and 0.4 ni to 3.0 m (profile I) 160 pmol/l) indicate a deficit by precipitation, thus to create densities of 100 to 200 mg/l on the 6.0 m to 4.0 m (profile II) consumption due to phytoplanktonic activity or ex ce^^ bottom. 1.5 to 2.2 (profile 111) m m by action of lateral fluxes. The downstream zone is very turbid and stratified at 0.4 m to 1.9 m (profile IV) the end of ebb (velocities in order of 60 cm/s) ' Dytiatnics u/sus/~et~dt.dinarters ¡ti the Barito esruory Al the surface at the end of flood: throughout the water column. Contents ranged from the upper salinities are located at the east of the inlet Suspended sediments originate for the most part in the 50-100 mg/l at the surface to 300 mg/l on the bottom. weathered basic rocks of the upper basin and consti- (from 7.6 to 34): During the rainy season, when leaching landivard is tuents of the prctertiary formations: schists, grauwackcs the lowest salinities arc located in front of the inlet very intense, ebb current velocities in the estuary are (Oertel, Soil Research Institute, Hehanussa, (from I to 1.8). 1972; 1973; sufficiently important to induce the migration towards 1981). On the bottom and dcspitc the low water depth, there the Barito inlet of a great quantity of sediments carried arc steep salinity grndicnts (Fig. 5). In the figure, the Crystalline, metamorphic and volcanic rock product in suspension. These tend to seal the mouth or the hachured zone shows Barito waters throughout the .:/ clastic materials are transported along the river. estuary. The suspended matter study was carried out during water column and rcvcals the presence of a prefcrential The tidal range becomes small relative to the strength cbh clianiicl running dong the right bank, whereas three tidal cycles at a time of spring tides. of river outflow. as in many tropical estuaries (Wright. flood p?efercntially enters by the left bank. i / A synthesis is provided in Figure 9. Within the estuary. 1977). we notice a flood-ebb dissymctry in duration, rcspccti- Helcrtioti.diips Iii~fivwiipli utid siilitii1.r iti Buritu rirer vcly 1/3-2/3. The dissymctry with curves of current Some authors (Kendrick. Derbyshire. 1983) have writ- In Iktrito rivcr. pl-l riingcs from that of freshwater to vclocitics appears upstrcotn 20 kni from the inlet. ten that from August to November. river flow multi- what is ohviously scawatcr. arc from 5.84 to 8.40. i.e. .. plied by as much as 3.5 the suspension transport. i IO 20 30 Flood wave propagation is powerfully inhibited by pCi 6). niorc than 2.5 units (Fig. SALINITY I%I the sedimentary mouth bar which increases bottom During the dry season. there is il retention or silt within Low pH values are duc: roughness. From the figure wc may see that: the estuary. It is very difficult to estimate the annual - first. to the pollution linked to industrial activities: The turbidity is less than 30 mg/l at 314 of ebb in the total of sediments transportcd in the Barilo estuary. - second. to the nature of the rocks located in the upstream studied zone. Only at the end of ebb are Kendrick and Derbyshire indicate an annual load closc uppcr watcrihctl. bottom velocitics sufficient to drag the sediments and to 2.5 million m'.

222 3 223 'R ' ,. .. ,- ' ... .. , , .. _. 4 ,? Pli 8ASSDULLET er d/ .. HYDROSEOIMENTOLOGY OF.THE ßANT0 ESTUARY r^' . . ... - .. ,' . ., I. .. ' , ~<'V' OII I-igurc Y Figure II ~ .f D' BASlN RIVER LBEVE y I I

29 14 I I Il I 28 17 28 .

By way of conclusion. a synthetic map (Fig. IO) of the THE SOILS ßarito cstuciry gives the perccnthges of distribution of the fraction less than 63 pm. blorphology Four catcgorics arc defined with fine elements percen- Most of the soil profiles are characterized by the pre- tage in the total sediment. Erosive trend zones are sence of a generally fibrous peat, sometimes compound- marked with a white arrow; zones characterized by ed with wood or leaf residues (Weiss, Da'i, 1974). The accretion phenomena are indicated by a black arrow. peat layer is more or less thick and generally located ..C. . . on the top horizon. rarely at the bottom and sometimes inside the profile (Fig. 1 I). In fact, it is often a peaty clay horizon with 10 YR 3/1-3/2 colour, rich in fibres and root residue, of half-ripe to ripe consistency, sticky Leqend: 101.3 W4 - So11 colour and plastic. Under Rliizopkorn forest, profiles are very 7.0 i :laasUrcd Cleld PH much like those we have observed in Senegal (Marius, 1984). homogeneous, very fibrous, with a strong smell of HIS. At the top horizon. fauna activity is vcry intense, mainly with crab holes. It thus appears that the main morphological characte- to form pyrite. Under reduced conditions, pyrite is The water is for the most part composed of sodium ristic of tlic soils is a half-ripe to ripe consistcncy which maintained in the soil but when aerated pyrite is oxidi- chloride. Chloride and sulphate are the main anions; shows that they are physically developed. sed to form iron sulphate, the soil becomes extremely sodium and magnesium are the main cations. In sea acid with a decline of pH to less than 3.5. Such rapid watcr the CI-/SO; ratio expressed in mmol/l is appro- oxidation will give jarosite KFe, (SO,), (OH),, which ximately 20 and we may note a good correlation Chemi~alpropertics lias a pale yellow colour. bctwcen lhc pH and the CI-jSO; ratio (Fig. 1.2). One of the main characteristics of mangrove soils is a Some 24 water samplcs were analised and the data AI an initial concIusioii, it niiuld appear that most of pl-l which is generally around 6-7 when measured in show that, cxccpt for R/iizop/ior~isamples, most-of the the soils of the surveyed area are potential acid sulphate tlie field on fresh samples and sometimes acid and water samples are not salinc. soils but not salinc soils. lower than 3.5 when measured in dried samples. The difference between the field measured pH and the dry klineralogical properties pH is called "potential acidity". This is typical in the c;w of most of the samples of the soils of the Darito All tlie samples were :in:ilised by X-ray diffraction for estuary. where thc field measured pH is around 6-7 powder fraction and 77 samples werc analysed for the and tlic air-dried pH is below 3.5. p:irticularly for clay fraction. smiplcs under Rlrirophurcr. Most of tlie profiles are - quartz. Laolinitc. smcctitc. pyritc. jarosite. feldspar thus "potcntiiil acid sulphate soils" or "potential cat- are prcscnt in the powdcr fraction: 51 cl;iys". Tlic potcnti;il acidity of these soils is due to . - kaolinitc and smcctitc :ire the two miin clayed mine- ;iccuiiiuliitioii of sulphides inainly in pyritic form. Tlic . riils prescnt in thc cl;iycd fraction associalcd with an :iccuniulation of pyritc looli pl;ice during scdinientn- chy. O IO 20 30 40 50 intcrlnqcrcd tinn. Sca w;iIcr sulphatcs :ire rcduccd into sulphidcs cljso; througli the influencc of sulphate-reducing bacteria I'inurc I2 Clsssificution of tlic soils conteincd within the sediment in a reduced envi- ronment end with a high content of organic matter. According to the soil taxonomy classification, most of Sulphide re:icts with iron from the upper watershed tlie soils may be dcscribcd 21s sulkiquent and sulfihcmist

3 224 225 ..

,. .. nlicit they itrc peaty. Some profiles are sullaquept. be developed in the area, the mangrove swamps being .. 1. Non-xid profiles of the rivcr levees are fluventic tropa- very rich in Jish. prawns and shrimps. qucpt. The Rhizophora forest of Pisali besar should be totally ..

protected as a natural forest rcserve where tourism I. LAND USE AND 1MPROVEMENT . . might be managed. ' .. . Rice. the main crop of the surveyed area, is cultivated in permanent flooded conditions during a period of CONCLUSIONS nine niontlis before harvesting and alter three succcs- From the scdintcntological point of view. during the sive transplantations. Rice is flooded by non-saline tide dry season. the Barito estuary is controlled by tidal

w;iter. This method, which is used by local populations currents. There is retention of silts within the estuary. I. IO prevent oxidation and acidification of the soils, is Rather violent winds during monsoon periods are lhe well adapted to the soil conditions but permits only main cause of a constant redistribution of the fine- i . one crop per year. Other crops include cocOHu1, grained particulate material at the river mouth. It is to banana. citrus. pineapple and cocoa. be regretted that data concerning the rainy season arc Agricultural conditions could bc improved by providing scanty. for a second crop of rice with short-term varieties, and The pedological survey carried out to the west of the , also by using a scparate system for irrigation and estuary resulted. irifer diu. in the discovery of a beauti- drainage. ful mangrove forest. Most of the soils of the surveyed ... . r\stociatctl with agrictilturc. aquaculture could easily area are potential acid sulphate, rather than saline soils.

RCt'ERliNCliS ,

I(:i~*nullctPh.. 19X.l. Siudy or the hydrordimentological processes Marius C., 1984. Conlribulion 5 I'iludc damangroves du SCnCgal williiri Darito estuary. Delta plilau Pctak. Kalimantan. Indonesia. et de la Gambie. 71Gsc Docl. Érot. Uniu. Louis Pasteur, Srrasbourg, IFREMER. Centre de Uresl. 8.2 p. 1984.309 p. Oertel C.E. 1972. Sediment lransport of estuary entrance shoats l:umvanrl J.. Chnntcíort A., 1978. Bioclimale of the Indonesian Archi- and lhe lormalion of swash platíorm$ J. Sediment. Petrol.. 42, 4. pclap. Instilul l:r:inqais de IhndichSry, Travaux de la Section Scien- 857463. . tifique el Technique. XVI. 104 p. Soil Raenrrh Imtitulq Bogor. 1973. Report on soil invaligation oí the Delti Pulau Pchk (South and Central KalimanInn). Ministry 11~1~1nus~nIL E.. 1981. I3iisic dmfrom Uarito detta. Soulh Kaliman- of Agriculture. Soit Research Inslilule, Uogor n' 5-1973. 146 p. inn. Indonesia. L.G.P.N.. L.I.P.I.. 21 p. (unpublished). Weirs hl., Da7 Y.. 1974. Ideas on lhe genesis and the íertilily of rcgioml peal in Indonesia. Congr. I.A.G.I.. Bandung Indonesia. Kcwlrick \l. IL. t)crb>\hire II. V.. 1983. Factors :~ífcciingthe supply \Vright L.D., 1977. Sediment transport and deposition at river :ml distribulion of sutinicnib in some tropical ports. Can. J. Fish. mouths: a synlhcsis. Doc. n" 70614. Grol. Soc. Am. Bull.. 88,857468. ,4,p1. Sri.. Jll. SuppI. I. 3.5-43.

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