sth WSEASlnt. Conf. on ENVTRONMENT,ECOSYSTEMS and DEVELOPMENT,Tenerife, Spain, December 14-16,2007

The efficiency of water reservoirs at the region of the former Lake Karla in Thessalyto meet irrigation requirements

P. LOKKASI, s. KorsoPoulos2, J. ALEXIOU', G. GRAVANISI, v' VASSILOGLOU"S. MAGALIOS,, V. KASSOS- 1: Departmentof Civil EngineeringInfrastructure Works, TechnologicalEducational Institute(TEI) of Larissa, 2: National Agricultural ResearchFoundation, Institute of Soil Classificationand Mappingof Larissa,GREECE 3: MScE SurveyorEng, Larissa, GREECE 4: Electro-MechanicalEng, Larissa, GREECE -p. p.lokkas @tei lar. gr http://users lellat -gt I lokkas

Abstract:-In theregion of ,atthe areawherethe former lake Karla extended, before it wasdrained' a numberof surfacereservoirs operate and supplythe sufficientwater quantitiesfor inigation of nearby cultivatedareas mainly during the period between June and August, when the inigationwater requirements are high,while the availatlewater from otherresources is negligible.In the presentstudy, monthly climatic data takenfrom the meteorologicalstation of theNational Meteorological Service (N.M.S.) in Larissa,Greece are utilisedfor the estimationof both the reservoir'sevaporation and the crop waterrequirements in orderto evaluatethe efficiency of reservoirsin meetingthese crop water requirements, with referenceto theirtechnical characteristicsand the size ofthe irrigatedareas'

Key-Words:- Irrigation,evaporation, reservoir, cultivation, evapotranspiration.

(11) 1 Introduction In the study regionthere are totally eleven reservoirs 2l that supply specific areas(totally Thessaly,from agricultural point of view, is the |, eight sub-regions)with irrigation water, as shown in most important part of central Greece, not only Fig. L because it is a non mountainous area, but also Thesereservoirs are filled up with water,through becausethe Pinios River, which crossesthe region, pumping, early in the springtimefrom Pinios River. makesthe plain highly fruitful. This water is then used to irrigate the local Since the ancienttimes (period of Herodotus),at cultivations during the water shorlage period the foothills of , there existed a lake named (mainly Juneand July). Viviis, which was consideredto be the place where ln the study area the cultivations irrigated by part of the surface waters of Thessaly plain were '70%o sprinkler and trickle consist of the total area, concentrated.This lake, today known as Karla, has leaving the rest 30o/oto non-irrigated, which are beendrained, since the last five decades. mainly serials. From the inigated areas cotton The cultivations at the region where the former covers about 85%, while the rest is cultivated by lake of Karla existed are irrigated mainly by water maize,alfalfa and processedtomato. that is stored into nearby reservoirs, which have Given the size of reseryoirs along with the beenconstructed for this purpose. inigated atea and the distribution of In the frame of the research programme corresponding it is considered more than necessary to "Archimedes - EPEAEK II", co-funded by the crops, the reliability of eachreservoir in covering European Social Fund & National Resourcesand evaluate the inigation water needs, taking always into realisedby the Dept. of Civil Engineeringof TEI of account the variability of climatic conditions from Larissa,Greece, under the title "spatial mappingand year to year. estimation of hydrological risk, emphasising the Methodologiesfor validating irrigation networks floods and draughtsin urban and non urban areasof have been proposed in the past for specific crop Thessaly and their environmental impacts", the 4].This work necessitatesmainly the aboveregion hasbeen selected as a study area. species[3, of both the evaporationof reservoirsand The researchaims at estimatingthe reliability of estimation evapotranspirationof crops on a monthly basis. the above structures,i.e. water reservoirs,covering the These estimationsare then utilised to calculatethe the essentialwater quantitiesfor irrigation. SthWSEAS lnt. Conf. on ENVIRONMENT,ECOSYSTEMS and DEVELOPMENT,Tenerife, Spain, December 14-16,2007

A L EGEND

r RESERVOIRS

M IRRIGATEDAREAS

KALAMAKI

Fig. 1: Reservoirsand irrigatedby them areasin the region of former Lake Karla water balance of each sub-region for a certain considered.All thesefeatures have to be taken into numberofyears. account in order to estimate the water shortage This project considers monthly climate data during eachyear and consequentlythe risk of failure taken from the meteorological station of the in water supply for irrigation. NationalMeteorological Service (N.M.S.) of Larissa The study area is close to the city of Larissa, along with soil data [5] and crop speciesdata of the where a meteorological station of the N.M.S. is study area, with the aim at estimating the water already in operation. The greater Larissa area is balanceof eachsub-region which is irrigated from a suffering by warm and dry summers.This period is certain reservoir.These estimations are then utilised crucial for crop gtowth, demanding for inigation to evaluatethe reliability of reservoirs in order to great quantities of water. At the plain part of the cover sufficiently the local irrigation water needs. county and especially at the region of the former Lake Karla, the prevailing temperaturesalong with other climatic parameterswhich determinethe level 2 Procedures- Methodology of evaporation and evapotranspiration of crop relative Each region of cultivation is characterisedby a species(solar radiation, sunshineduration, practically consideredto number of parameters,such as water evaporation humidity, wind speed)are by the N.M.S. of from reservoirs, crop water needs, rainfalls and be the same to those recorded reduction of soil moisture. which have to be Larissa. sth WSEASf nt. Conf.on ENVIRONMENT,ECOSYSTEMS and DEVELOPMENT,Tenerife, Spain, December 14-16,2Q07

3 Calculation of evaporation and calculatedthrough the equation: evapotranspiration 0.408L(Rn-G)+y - e) The most reliable method for the calculation of ETo ,9Yruz@s ,r.r, evaporationand evapotranspirationin our days is the L+y.(l+0.34.u2) modified method of Penman-Monteith,as described following symbolsrepresent: in FAO-56[6,7, 8]. wherethe The methodis applied in two stages.Initially the o ETo evapotranspirationof referencecrop (mm/d), 1), evapotranspirationofthe referencecrop is calculated o Rn net solarradiation (MJm-2d and then crop evapotranspirationis estimatedusing . G soil heat flux density lvJm'd-1) which here the correspondingcrop coefficient as shown in the canbe considerednegligible (G nv0), following relation o T meanair temperatureat2m height ("C), o uz dyaraEewind speedat the sameheight (-r-t), ET,=Kr'57o, (3.1) . essaturation vapour pressure(kPa), . e0actual vapour pressure (kPa), where are: ET6 the daily evapotranspiration(mm/d), o A slope of saturation_vapour curve at a K6 the crop coefficient which is dependanton the temperatureT (kPa"C-')and stage of the crop development [6], and ETo the o y the psychrometricconstant 1kPa"C-'). evapotranspirationof the referencecrop (mm/d). For the evaluationof \, the estimationof extra Evaporation can be calculatedin a similar way terrestrial radiation (R.) is essentialalong with the throughthe equation maximum sunshine duration (N) which can be realisedthrough periodic functions [10]. E = Kc 'ETo, (3.2) Throughequations (3.1) and (3.3) alongwith the monthly rates of climatic parameters(temperature, where are: E the daily evaporation(mm/d) and K6 sunshineduration, relative humidity and wind speed) the surface coefficient, which, for shallow water for the years 1955-1997taken from the N.M.S. of surfacestakes the valueof 1.05[6]. Larissa,the monthly rates of evapotranspirationfor The evapotranspiration of reference crop is the above period of 43 is calculated.These results determinedthrough the modified Penman-Monteith are presentedin Fig. 2 for the period 1990-94. method as describedin FAO-56 [6, 8] and is

5.0

S 4.0

; 3.0 F rr'1 2.0

1990 r991 t992 1993 1994

Fig.2: Calculatedvalues of referencecrop evapotranspiration(mm/d) at Larissafor the years 1990-94 sth WSEASlnt. Conf. on ENVIRONMENT,ECOSYSTEMS and DEVELOPMENT,Tenerife, Spain, December 14-16,2007

Table 1: Technicalcharacteristics of reservoirsalong with the sub-regionsthey serve

Technical characteristics of reservoirs Corresponding servedsub-regions

e* b. I !'i^ ON s s s 9=tr ESE q) Ei Reservoir 'E<=h0 Lo N qE J:6 t-l ? d- i= I U EleftherionI, II t,70 600 4000 85 l5 2 Dimitra r.00 400 2600 85 l5 J PlatikamposI 0.50 250 1500 85 10 5 4 PlatikamposII t.4s 500 4560 85 l0 5 5 Glafki 2.10 550 5415 85 l0 5 6 NamataI. II 2.90 983 10000 80 l0 5 5 Kastri r.l0 350 4900 85 l5 8 Kalamaki I, il 8.00 2750 20000 85 l5

4 Calculationof water balance regions. The validation of reservoirs' reliability of the study area necessitatesthe water balance of each 5 Resultsand discussion sub-regioninigated by a certainreservoir system. The results of calculationsare shown in Table 2. The water balanceis estimatedper year and takes They refer to the averagereliability of reservoirsR-, into account the technical characteristics of its standard deviation, SDn and the variation reservoirs (capacity, water surface) along with the coefftcient,CVp, that comefrom a simulationperiod evaporationrate [9], the size of inigation areasand of43 years. the crop water requirements,the rainfalls and the As reliabilityof a reservoiris definedthe ratio of reductionof soil moisture. its capacity over the total water needs of the sub- The data used for the calculationsare presented region which is served.The value I of reliability - on Table I and refer to the technical characteristics which is its maximum one - meansthat the crop of reservoirs[2] along with the servedby them sub- water requirementsare completely satisfied.

Table 2: Reliability of reservoirsfor the studyregion

Variation Standard Reservoir Average rate, R. Coefficient, CVp, Deviation, ^SDa oA I EleftherionI. II 0.832 0.113 r3.6 2 Dimitra 0.758 0.116 15.3 3 PlatikamposI 0.660 0.109 16.5 4 PlatikamposII 0.667 0.105 15.8 5 Glafki 0.816 0.1l5 t4.l 6 NamataI, II 0.610 0.099 16.3 Kastri 0.483 0.082 t7.0 8 Kalamaki I, II 0.800 0.111 13.9 sth WSEASlnt. Conf. on ENVIRONMENT,ECOSYSTEMS and DEVELOPMENT,Tenerife, Spain, December 14-'16,2007

Taking into account the values of the above to the averagereliability ofreservoirs for a period of parametersthat refer to the reliability of reservoirs 10 yearsand a probability l0%. for the study region and the assumptionsof the It is estimatedthat the most reliable reseryoirsare CentralLimit Theorem[], 12, 13, l4], a general those of EleftherionI & II (78,7%) followed by classification of those reservoirs is feasible Glafki (76,9yo),Kalamaki I & II (75,5oA),Dimitra according to their reliability under specific (7l,lyo), Platikamposll (62,5yo),Platikampos I conditions. (6l,6yo),Namata(57,0%) and Kastri (44,9%). The validation is typically realisedwith respect The aboveresults are depictedin Fig. 3.

f.,l )t A

LEGEND - iddHfiv6id5' f:-f du-/u % E 70-60 % - 60-50 0/6 ] I ffi 50-40 %

" ,Iil.

-..>f, :l .,;: / ..,.:'t :t .,//\ X../ a:,' .tt::.:', '=',-'. 'i ';l;;;;;;1 './a:t -))^''' 1----*

Fig. 3: Averagereliability of reservoirsin the region of Karla for a decadeand a probabllity l0%

6 Conclusions a) The reliability among the different reservoirs From the calculatedvalues of shortageson the of the study area may not be the same.Reservoirs water balancefor each sub-regionofthe study area usually do not cover the total local crop water (part of the former Karla Lake) - that take into requirements.On averagethey cover only a part of -8304), account the variability of climatic conditions for a them (48 dependingon the conditionsofthe period of 43 years,the size of reservoirsalong with sub-regionwhich is seruedby each reseryoir. The the size ofthe irrigated areasand the distribution of most reliable reservoirs,according to characteristics crop species- the following conclusions can be presentedabove, are those of Eleftherion I & II, drawn: Glafki, and Kalamaki I & II while last comesthe one sth WSEASlnt. Conf.on ENVIRONMENT,ECOSYSTEMS and DEVELOPMENT,Tenerife, Spain, Decemb er l'4-16,2007

of Kastri. on the Water resourcesmanagement for drought b) The inigation needs for the cultivated areas proneregions of Greece. 1999,pp.20-27. that are served by the same reservoir may not be [6] Allen R. G., PereiraL. S., RaesD. and Smith equally satisfied from year to year, due to different M., Crop Evapotranspiration: Guidelines climatic for conditions. This variability, expressed computing crop wqter requirements, FAO through the variation coeffrcient,fluctuates between Irrigation and Drainage Paper No 56, FAO, -13,5- l1yo. Rome,1998. The above reliability analysis for the structures [7] KotsopoulosS., KalfountzosD., Alexiou L, used to store water for irrigation, may be a useful Zerva G., KaramaligasC. and Vyrlas p. Actual tool for a further constructionof new ones, so that, evapotranspirationand soil moisture studies in at last, they fulfil the corresponding local irrigation irrigated cotton fields, European Water (e- waterneeds. bulletinof EWRA), Issue3 I 4,2003, pp. 22-28. [8] Kotsopoulos S. Hydrolog,,, Ion Publications, ,2006. References: [9] KotsopoulosS., Alexiou J., Lokkasp., Gravanis tl] Land Reclamation Dept. of Larissa. Land G. and Magalios S. Estimation of evaporation Reclamation Works - - Actions Aims, Larissa, lossesfrom the reservoirs of Larissa county, 2005. Proceedingsof the l0' National Conferenceof [2] GoumasK. The irrigations on Thessalyplain; EYE,Xanth|2006, pp. 103-l10. consequenceson the ground and surfacewaters, [0] Kotsopoulos S. and Babajimopoulos C. Proceedings of EYE meeting: Water Resources Analytical estimation of modified penman and Agriculture, Thessalonica, 2006,pp. 39-53. equationparameters, J. Irrig. and Drain. Engng., [3] Kotsopoulos S. L On the evaluation of risk of ASCE Vol. 123(4), 1997,pp. 253-256. in ph.D. failure irrigation water delivery, Thesii Il] Haan C. T. Statisticol Methods in Hydrology, Southampton University, UK, 1989. The Iowa State Universiql press, Ames, Iowa, [4] KotsopoulosS. and Svehlik, Z. Riskoffailure in 1971. irrigation systems: proc. Its estimation, of the [2] Kite G. W. Frequency and Risk Analyses in EWRA 95 Symposium on Water Resources Hydrologt, Water Resources publications, under Drought or Water Shortage Conditions, Colorado,1985 Nicosia,Cyprus, 1995,pp. 243-250. [13] Yevjevich V. Probability ond Statistics in [5] KalfountzosD., Alexiou J., MagaliosS., Vyrlas Hydrologt, Water Resources publications, P. and Tsitsipa G. An expert systemfor the Colorado,1982 integrated management of irrigation wqter. l14l Chatfield C. Statistics Technologt, Special .fo, application on ,the region of LOLR Chapmanand Hall, London,1983. Pinios, Proceedingsof 4b National Conference