Agricultural Research Institute, Oromia Regional State, Ethiopia

Transcription

1 Technical Performance Evaluation of Ketar Medium Scale Irrigation Scheme, Southeat of Oromia Regional State, Ethiopia 1 Dinka Fufa (BSc in Agricultural Engineering and Mechanization, MSc in Irrigation Engineering) 1 Soil and Water Engineering Reearch Team, Aella Agricultural Engineering Reearch Center, Oromia Agricultural Reearch Intitute, Oromia Regional State, Ethiopia Abtract Evaluation of performance of irrigation ytem ha been increaingly treed in recent year by many reearcher and manager of irrigation cheme. Thi tudy wa aimed to contribute to the improvement of irrigation efficiency and crop productivity of the farm. It had been conducted on Ketar medium cale irrigation cheme ituated in Ari zone Oromia Regional State of Ethiopia. Performance indicator ued were conveyance, application, torage efficiency, water application uniformity; depletion fraction, runoff ratio, deep percolation, irrigation water ue efficiency and cheme utainability were done. Potato wa the elected crop for the experiment. Soil of the tudy area wa found clay loam, moderate acidic, non-aline oil and ha 3.44 OM in average. Average E c,, E a, E u, E, DF, RR, DPF, IWUE of Ketar cheme wa found a 57.4%, 61.6%, 61.6%, 160%, 70.1%, 27.86%, 10.54% and 2.38kg/m 3, repectively. The tudy wa concluded a upper and middle tream uer were conuming more water than the lower with decreaed productivity of the cheme and technical upport and SWC activitie in thi waterhed and redeign are recommendable for utained deign dicharge. 1. Introduction Low level of performance can be identified at any level and tage of irrigation ytem. At ytem level, the tatu of cropping intenity and yield from many irrigated area are uually unatifactory. Thee low performance occur in irrigation though it i a technological package that feed billion of people. Good performance i not only a matter of high output, but alo one of efficient ue of available reource (Rut and Snellen, 1993). Improper irrigation practice lead to inefficient water ditribution, non uniform crop growth, and exce leaching in ome area and inufficient leaching in other, all of which decreae the yield per unit of land area againt per unit of water applied (Strelkoff et al., 1999). Evaluation of performance of irrigation ytem ha been increaingly treed in recent year by many reearcher and manager of irrigation cheme. In the field of irrigation ytem management, performance evaluation of irrigation ytem i the key iue (Selehi et al., 2010). Hence, thi tudy wa planned to undertake with the general objective of evaluating the performance of Ketar medium cale irrigation cheme that i one of onion and potato producing farm in Ari zone of Oromia Regional State. The pecific objective of the tudy were evaluating urface irrigation efficiency of Ketar medium cale irrigation cheme and determining the level of water productivity of the farm on which performance evaluation would be conducted uing Potato a a repreentative crop. 2. Material and Method 2.1. Decription of Study Area The tudy ha been conducted on Ketar medium cale irrigation cheme ituated in Tiyo woreda of Ari zone Oromia Regional State of Ethiopia. It feed Aboera Alko, Ketar Genet and Hama Gaha kebele. Average annual temperature i 13.8 C. The average annual rainfall of the woreda i 1118 mm. The woreda ha an altitude of 2430m above ea level (al) (Yazachew and Kaahun, 2011). 13

2 Figure 1. Location Map of Study Area 2.2. Field Layout Potato crop wa elected for the experiment for elected plot. Experimental deign wa baed on completely randomized complete block deign (RCBD) type. Figure 2. Experimental Field layout 2.3. Soil Sampling Double ring infiltrometer of diameter 60cm (outer ring) and 30cm (inner one) wa ued to meaure oil infiltration. Hydrometer method wa ued for analyzing particle ize ditribution and USDA textural triangle (USDA, 1972) wa ued to identify the textural cla. Organic matter content of the oil wa determined by titration method. Soil ph wa determined by uing water upenion with oil to water ratio 1:2.5 by ph meter. EC wa determined by method of water upenion with oil to water ratio 1:2.5 by electro conductivity meter. Unditurbed oil ample were collected by core ampler and taken to dry oven at 105 C for 24hr to determine M bulk denity (Hillel, 2004). ρ b = (2.1) t Where: ρb = oil bulk denity (gm/cm 3 ), M =ma of dry oil (gm) and t =total volume of oil in the core ampler (cm 3 ) 2.4. Crop Water Requirement (CWR) and Irrigation Water Requirement (IWR) Neceary climatic data wa proceed to CROPWAT verion-8 to calculate the reference evapotranpiration 14

3 (ET o ) of the tudy area uing data of Chebi meteorological Station and National Meteorological Agency. ET c wa computed a hown in equation 3.2. Then CWR and IWR were computed. ET c = ET o xk c (3.2) where, ET c = crop evapotranpiration (mm/day), ET o = reference crop evapotranpiration (mm/day), K c = crop coefficient, Irrigation interval wa calculated a; 2.5. Inflow and outflow water meaurement at field Dicharge meaurement at elected point were done by current meter, tructure (trapezoidal and rectangular weir) and three inch Parhall flume (at field channel).for 3 inch Parhall flume, (2.3) and Q t a = * (2.4) Q= H where; H=water level height in Parhall flume, Q= dicharge through the flume (l/), a = total volume of water applied (m 3 ), t =flow time to the field (econd) 2.6. Gravimetric ampling Moiture tatu of the oil profile for each field wa meaured before and after each irrigation event. Moiture ha been calculated a a percentage of dry weight of the oil ample ( ϑ m ) uing the following formula, Mt M M w ϑ m = *100= %*100 (2.5) M M where, m ϑ = oil moiture tatu in weight bai (%), M t =weight of freh ample (gm), W =weight of over dried ample (gm) olumetric moiture content ( θ v ) ha been calculated uing a, where, θ v=volumetric moiture content (%), ρ θ ϑ * ρ w = unit weight of water (gm/cm 3 ) b v = m (2.6) ρw 2.7. Total Available Water (TAW) Required amount of water for each irrigation event wa meaured uing the water balance approach. TAW wa ( FC PWP) computed a, TAW = * BD * D (2.7) 100 where: TAW=total available water (mm), FC=field capacity (% by weight bae),pwp=permanent wilting point (% by weight bae), D=depth of root zone (mm), BD=pecific denity of oil (bulk denity of oil) (gm/cm 3 ) 2.8. Determination of Irrigation Sytem Performance Indicator Irrigation efficiencie Conveyance efficiency It i expreed a: E = * 100 c f t where, E c = Water Conveyance Efficiency (%), f = olume of irrigation water that reache the farm or field ( m 3 /), t = olume of irrigation water diverted from water ource (m 3 /) f wa meaured by Parhall flume for the nine plot and t wa obtained by current meter to obtain mean velocity and proceed to tandard formula (Q=Ax) Application efficiency It i expreed a: * 100 f (2.8) E a = (2.9) Where: E a =Water application efficiency (%), =olume of irrigation water tored in the root zone (m 3 / or ham), f = olume of irrigation water delivered to farm or field (m 3 /) wa determined by calculating available water in the root zone in either volume bae or weight bae by determining oil moiture content before and two day after irrigation by gravimetric method for the nine elected plot

4 Application uniformity It wa expreed a: * 100 Dlq D u = (2.10) D av Where: D u =Ditribution Uniformity (%), D lq =Average depth of water infiltrated in the low one-quarter of the field, D av =Average depth of water infiltrated For computing D av, moiture content of the field wa meaured before and after irrigation. Their difference and mean of their difference were calculated. For computing D lq, moiture content of the field wa meaured before and after irrigation Water torage efficiency (E ) E i defined a the ratio of the volume of water tored in root to volume of water required filling the root zone to ai bi near field capacity and expreed a, E = * 100 (2.11) W W fc W W bi Where: E =Soil water torage efficiency (%), W bi =Weight of oil moiture before irrigation, W ai = Weight of oil moiture after irrigation, W fc =Weight of oil moiture at field capacity W fc in the crop root zone wa determined from oil ample taken from the nine plot by uing preure plate apparatu. W bi and W ai wa meaured by taking irrigated oil ample from nine plot and drying it by oven for 24 hr at 105 c Irrigation water loe i. Runoff ratio (R.R) The amount of runoff from each field wa collected and meaured uing known volume of runoff collector bucket and Parhall flume wa intalled at the lower end of the field and runoff wa calculated uing the Dr equation given by Walker (2003) a; RR= * 100 (2.12) Da Where: RR=runoff ratio (%), D r =volume of runoff in term of depth (mm), D a =total depth of water applied to the field (mm) ii. Deep percolation fraction (DPF) Deep percolation fraction could be calculated indirectly from value of application efficiency (E a ) and runoff ratio (RR) a given by FAO (1989); DPF=100-E a -RR (2.13) Water productivity and relative irrigation upply of the cheme Water productivity of the tudy area wa determined from water applied to the farm throughout the growing eaon of the elected crop (Potato) and yield harveted from each plot. Ya It wa computed uing a, IWUE = IW (2.14) Where: IWUE- irrigation water ue efficiency (kg/m 3 ), Ya - actual yield (kg/m 2 ), IW - irrigation water applied (m 3 /m 2 ) 2.9. Sutainability of Irrigation Sytem The implet meaure of utainability i that quantifie the cumulative effect of negative impact i utainability of irrigated area (SIA) that wa calculated by the expreion given by Nelon (2002) cited by Awel (2009) a, AC SIA= (2.15) AI where: AC= current total irrigated area (ha), AI= total irrigated area when the ytem development way completed (ha), SIA =utainability of irrigated area Data Analyi Collected data during the tet of the ytem by uing performance indicator were fed to Microoft excel and wa analyzed tatitically. ANOA of required comparion parameter were done by uing SAS. Comparion of efficiency indicator of the tation were done by Leat Significance Difference (LSD). 3. Reult and Dicuion 3.1. Scheme Characterization The cheme ha deign dicharge of 0.86m 3 / and oberved dicharge wa 0.80m 3 /. Mot of it ha earthen canal which lead to eepage and deep percolation lo. 16

5 Table 1. Quantity and length of tructure of Ketar cheme No Particular Quantity Length 1 Irrigation pond 3-2 Main canal 1 11,713 3 Secondary canal 9 11,253 4 Tertiary canal 19 5,633 5 Area boundary 29-6 Farm boundary 3-7 Diviion box 16 Table 2. Irrigated area and Uer (H/H) of Ketar Irrigation Scheme rehabilitated by Community and OWRB with JICA cooperation (2000 E.C, 2008) Area (ha) H/H Sub Station Station=> Ketar 1 Keta-2 Ketar 3 Ketar 1 Keta-2 Ketar Total Crop Water Requirement and Irrigation Water Requirement Average ET c value of 19 year ( ) of the tudy area wa 4.43 mm/day for Potato from January-May at Chebi Meterological tation. Net and gro irrigation requirement wa 463.4mm for Potato from for one eaon (January to May). Table 3. ET c computation for Potato uing CROWAT Model-8 Station : Chebi, Altitude: 1544m, Latitude: 7.83, Longitude: Month Decade Growth Stage Kc ET c ET c Eff rain Irr. Req. Coeff mm/day mm/dec mm/dec mm/dec Jan 2 Initial Jan 3 Initial Feb 1 Development Feb 2 Development Feb 3 Development Mar 1 Mid Mar 2 Mid Mar 3 Mid Apr 1 Mid Apr 2 Mid Apr 3 Late May 1 Late May 2 Late May 3 Late Average Total Under field condition, potato water requirement i 350 to 650 mm during growing period, which i dependent on climate and cultivar. Etimated irrigation requirement for Ketar wa 463.4, which wa in the range of the one tudied by Sood and Singh, (2003). 17

6 3.3 Inflow and Outflow Water Meaurement at Field Table 4. Dicharge oberved uing 3 Parhall Flume at field channel of elected farm Station Plot Average Height Average Dicharge (m 3 /) Average Irrigation Period Mean water applied at each Growth Stage Irrigation Frequency (day) Total water delivered to farm (m 3 ) *10-3 (Sec) (m 3 ) Ketar Ketar Ketar Average Phyico-Chemical Propertie of Soil Soil ph value indicated moderate acidic oil ( ). It wa concluded that the cheme oil wa clay loam. According to Clae of alinity and EC (1 ds/m = 1 mmho/cm; a adapted from USDA (1998), oil which ha electrical conductivity 0<2 mmho.cm i non-aline oil Soil Moiture Content and Bulk Denity From oil ample collected at depth of 0-30 and cm, average oil moiture tatue were found a 34.90, and 25.63% repectively for Ketar-1, Ketar-2 and Ketar-3. Bulk denitie were found a 1.17, 1.10 and 1.09 g/m 3 for Ketat-1, Ketar-2 and Ketar-3 tation repectively. Average bulk denity of the cheme wa found a 1.12 g/m Total Available Water (TAW) Average total available water (TAW) for Ketar-1, 2 and 3 tation at 600mm depth were found a 79.25, 75.28mm and 71.05mm repectively. Average TAW of Ketar cheme wa Irrigation Efficiencie Conveyance efficiency (E c ) Conveyance efficiencie were found a 66.86, and 48.90% at Ketar-1, Ketar-2 and Ketar-3 main canal repectively. E c of the cheme wa etimated a 57.40%. A tated by FAO, (1989), for earthen canal length >2000m contructed on clay oil it E c would be 80% where a 95% for lined canal. From that reult it i concluded that E c of Ketar cheme wa poor Application efficiency (E a ) Average application efficiency of the tation indicated that, it wa in range of and 65.51%. Average E a of the cheme wa 61.60%. Irrigation management can improve efficiency by 5-20% by applying the right depth of water in the right place at the right time (Roe, 2006). The reult of plot one at Ketar-1 how that there were runoff loe at the tail of furrow due to much water application which did not match with oil infiltration for clay oil, ince oil of tudy area had lower value of infiltration rate. According to FAO (1989) E a for urface irrigation i 60%. Baed on thi, Ketar-1 and wa not efficient, where a Ketar-2 and 3 were efficient Application uniformity (D u ) Application uniformitie were found in range of and Average application uniformity of the cheme wa From thoe reult, application uniformity among the tation were omewhat the ame but different among plot. Operating the ytem at flow rate below or above the deign flow rate could lead to inefficient and non-uniform application a een among plot Water torage efficiency (E ) From data collected and mean taken at three depth,(0-30, and 45-60cm) average water E were %, % and 136.5% for Ketar-1, Ketar-2, and Ketar-3 repectively. It wa % for the cheme. According to Michael (2008), the importance of determining E i that, when water upplie are limited or when exceive time i required to ecure adequate penetration of water into the oil Depletion fraction (DF) An average depletion fraction of the cheme wa 70.10%. Bo et al., 2005 tudy indicated that decreaing depletion ratio (DR) would lead to riing ground water table, which increaed the rik of oil and ground water alinity. Therefore, deep percolation hould be kept at lower value be on the afe ide particularly for Ketar-1. Plot ize (m 2 ) 18

7 Irrigation water loe The cheme ha 27.86% mean runoff and 10.54% mean deep percolation. Thi indicate ince the oil of the tudy area wa clay and clay loam, it deep percolation wa lower than runoff becaue there wa lateral movement in addition to vertical flow of water in uch type of oil Water productivity and relative irrigation upply of the cheme Average productivity which wa expreed by irrigation water ue efficiency wa 2.38 kg/m 3. According to Sood and Singh (2003), Potato require 0.35 to 0.8 m 3 of water to produce 1 kg of tuber dry matter. Thi implie that water productivity i kg/m 3. A Ketar cheme water productivity wa 2.38 kg/m 3 it wa in the range of tudy done by Sood and Singh (2003). 3.8 Sutainability of Irrigation Sytem From tudy conducted utainability of the cheme wa Current command area i 26% greater than the deigned one. Table 9. Deign and current command area of Ketar cheme Station Deigned Command Area Current command Area Ketar Ketar Ketar Scheme Sutainability of Irrigation Sytem 4. Summary, Concluion and Recommendation 4.1. Summary and Concluion In thi tudy, an attempt wa made to evaluate the performance of Ketar medium cale irrigation cheme uing irrigation performance indicator on the tation and three plot from each tation. From the tudy the cheme ha 57.40, 61.60, 61.60, 160.0, 27.86, conveyance efficiency, application, application uniformity, torage efficiency, runoff ratio were found and deep percolation fraction. Baed on ANOA tet and LSD, there wa ignificant difference among tation in irrigation water ue efficiency at 5% and 10% ignificant level and there wa no ignificance difference for other efficiency indictor at both ignificance level. From tudy conducted farmer in uptream and middle tream were uing exce water and iltation had affected night torage in downtream which caued hortage of water in addition to the influence of up and middle tream water uer. There i alo mi management of water a there are loe at different Recommendation To reduce iltation problem of Ketar-3 night torage oil and to increae dicharge of the cheme it i recommendable to do waterhed management of the cheme by practice like oil and water conervation activitie in the waterhed in addition to newly deigned reervoir. It i alo recommendable to contruct ilt excluder at a point before water enter the reervoir to protect ilt accumulation. 5. Reference 1) Awel Seid Field management of the weha mall cale irrigation cheme, Southern Ethiopia. MSc Thei, School of Water Reource and Environmental Engineering, Department of Irrigation Engineering, Haramaya Univerity, Ethiopia. 2) Bo, MG, Burton, MA, and Molden, DJ Irrigation and Drainage Performance Aement: Practical Guideline. CABI Publihing, Trowbridge, US ) Brown, T Water Efficient Irrigation Study Final Report. Seattle Public Utilitie, Reource Conervation. California. USA. 4) FAO (Food and Agricultural Organization) Irrigation water managent and irrigation cheduling. Natural Reource Management and Environmet. Rome.Italy 5) Hillel, D Introduction to Soil Environmental Phyic. Univerity of Maachuett. Eliivier Acadamy Pre. New York.USA. 6) Michael, A. M Irrigation Theory and Practice. 2 nd Edition, IKA publihing houe pvt.ltd. New Delhi, India. 7) Roe, E Irrigation Efficiency Gap Review and Stock Take Sutainable Farming Fund and Irrigation New Zealand Report No L05264/2. Kinnect Group Publiher. New Zealand. 8) Rut, O.H.M. and Snelley, W.B Irrigation ytem performance aement and diagnoi, IIMI, ILRI, Colombo. Sri Lanka. 9) Schutter, E.E., Kanfman, C. and Peter, J.B The influence of ample ize and heating time on oil wieght lo on ignition. Univerity of Wicunin, USA. 19

8 10) Selehi Bekele, Makonnen Louleged, and Ater Denekew Impact of Irrigation on Poverty and Environment in Ethiopia Draft Proceeding of the Sympoium and Exhibition. International Water Management Intitute. Addi Abbaba. Ethiopia 11) Sood, M.C. and Singh, N Water Management. In: Khurana, S.M.P., Minha, J.S.,Pandey, S.K., (ed.) The potato:production and utilization in Sub-Tropic. Mehta Publiher, pp U.S. Dept. of Agri. (Soil Con. Service).1967b Irrigation water requirement.t.p.21. NewDelhi, India 12) Strelkoff, T.S., Clemmen, A.J., El-Anary, M. and M. Awad Surface-irrigation evaluation model: application to level bain in Egypt. Tranaction of the ASAE, 42(4): ) USDA (United State Department of Agriculture) Soil urvey laboratory method and procedure for collecting oil ample. oil Survey Invetigation Report I. U.S. Departement of Agriculture, Wahingiton D.C, USA. 14) Walker, W.R Surface irrigation imulation, evaluation and deign. Uer guide and technical documentation, Utah tate univerity, Hugan, Utah, USA. 15) Yazachew Etefa and Kaahun Dibaba Phyical and Socio Economic Profile of Ari Zone and Ditrict, Bureau of Finance and Economic Development Regional Data and Information Proce. Addi Ababa, Ethiopia Appedix Table 10. Dimenion of tructure and conveyance efficiency of Ketar cheme Structure Place Canal type Canal hape Top width Bottom width Water level width Water depth at left ide Water depth at center Water depth at right ide Average depth Dicharge (m 3 /) Diverion weir Lined Trapezoidal Ketar-1 main canal Earthen Irregular Ketar-1 econdary canal Earthen Irregular Ketar-1 tertiary canal Pipe 7.62cm) Ketar-2 main canal Lined Rectangular Ketar-2 econdary canal Lined Rectangular Ketar-2 tertiary canal Earthen Irregular Ketar-3 main canal Lined Rectangular Ketar-3 econdary canal Earthen Irregular Ketar-3 tertiary canal Pipe Circular Ø=8cm) Average Scheme E c (%) 57.4 Conveyance Efficiency (E c) (%) 20

9 Figure 3. Layout of Ketar Irrigation Scheme Station 21