Irrigation and Drainage Engineering

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HYDRAULIC MODELING AND FLOOD MAPPING OF HAROSHA RIVER WITH HEC-RAS AND HEC-GeoRAS MODELS IN TIGRAY, ETHIOPIA
(Hawassa University, 2017-03-10) MULUGETA TAREKE ABEBE
The Harosha river catchment is found in Tigray region in Raya Valley. This study area is surrounded by Waja and Tumuga catchment in the south and Harosha, Limeat and Harle catchment in the North and also it is the upper south part of the Raya valley catchment. The area is also dominated by undulating terrain with relatively steep to moderately steep and flatter slopes in the downstream of the catchment. Harosha flood plain has been vulnerable to high flooding from rainfall during rainy season. Also the main causes of these damages are land use changes from years to years and the main objective of this study is to estimate peak flood for various return period and prepare flood inundation mapping that can be used as decision support system for future intervention. The data used for this study was annual daily maximum rainfall, DEM, land use land cover map, and soil map and the flood frequency analysis of annual maximum daily rainfall was analyzed. The SCS rain fall-runoff method, HEC-RAS, HEC-GeoRAS and ArcGIS environment are used to determine the peak flood for different return periods. The simulation result for return period of 5, 10, 25, 50 and 100 year floods magnitude are 347.4, 383.7, 420.8, 443.6 and 463.1m 3 /s respectively. The maximum flood hazard and flow depth maps for a return periods of 5, 10, 25, 50 and 100 year are 84.6 and 3.36; 86.1 and 3.84; 86.9 and 4.35; 87.1 and 4.91; and 87.7 hectare and 5.89 m respectively with a maximum velocity of 4.6 m/s.
PERFORMANCE EVALUATION OF FURROW IRRIGATION IN BELLES SUGAR DEVELOPMENT PROJECT SUGARCANE FARM LEVEL, ETHIOPIA
(Hawassa University, 2017-04-29) ADUGNAW ASEFAW NIGATU
Evaluation of farm irrigation system plays a fundamental role in improving surface irrigation and in providing information used to advice irrigators how to improve their system operation. Furrow irrigation is one of the common methods of applying water to sugarcane at Belles sugar development project Sugarcane Plantation. The plantation is facing problems with respect to irrigation water management. This study was initiated with the objectives of evaluating the performance of furrow irrigation system at a farm level. To evaluate the performance of furrow irrigation system, a soil laboratory and field measurements (field layout, furrow geometry, time of cutoff, discharge) are made. The soil infiltration parameters „a‟, „k‟ and „fo‟ for each irrigation event are determined based on a two point approximation to volume balance method that incorporated modified Kostiakove Lewis infiltration function. Statically comparison of models outcome found the Win SRFR simulated model values provides good fitter than the SIRMOD simulation values to the estimated values. The analyses of the performance of the furrow irrigation in terms of application efficiency (Ea), distribution efficiency (Du), storage efficiency tail water Ratio (TWR), and Deep Percolation (DP) were done and found to be, the average application efficiency 62.1%, 65.3% and 68.5% for SIRMOD, estimated and WinSRFR simulated values; distribution efficiency 90.4%, 92.4% and 95.5% for estimated, SIRMOD and WinSRFR simulated value; storage efficiency 24.1%, 26.4% and 32.8% for SIRMOD, WinSRFR simulated and estimated values; TWR 31.2%, 34.2% and 37.9% for WinSRFR, estimated and SIRMOD simulated values, respectively and deep percolation ratio for all estimation is null. From the sensitivity analysis furrow slopes are higher sensitive than other parameters on influencing the application efficiency. The effects of furrow lengths are highly influencing on TWR. The effect of discharge influence on the storage efficiency also high with compared to others whereas the time of cutoff found affect the distribution efficiency
W YTIVITCUDORP DNA DLEIY ER S NOP SE FO NOINO DNU RE LLUF DNA ICIFED T NOITAGIRRI NI W RETA S ECRAC AERA , M OKERA ,ADEROW ET IPOIH A
(Hawassa University, 2017-07-06) KE ARD LA AW BELA UH SSEN
hserF retaw si acs r ec in ynam strap fo ht e dlrow dna nimoceb g a labolg a .adneg erutlucirgA si eht tsegral gnoma s tce o sr hcihw era snoc u gnim eguh hserf retaw . ehT sevitcejbo fo siht duts y erew ot evorpmi larutlucirga retaw ytivitcudorp a dn etagitsevni eht dleiy esnopser fo noino porc ot retaw .ticifed ehT dohtem deyolpme pmocne a sess dleif tnemirepxe ni dezimodnar telpmoc e kcolb ngised ( BCR D) htiw nevele stnemtaert na d eerht .snoitacilper ehT stnemtaert :erew lluf noitagirri ( %0 ticifed sa lortnoc ), %52 fo CWR ticifed tuohguorht org wing %05,nosaes fo CW R ticifed tuohguorht worg i gn ,nosaes dna eno p doire ticifed stnemtaert (25% dna %05 fo CW R ticifed ta in laiti , ,tnempoleved dim dna etal s egat s). ehT xe p tnemire saw deirrac tuo ta okeram aderow nrehtuos .aipoihtE stluseR dewohs taht secnereffid ni rri i tag noi retaw tnuoma yltnacifingis tceffa yponac ,revoc blub dleiy dna a evob dnuorg ssamoib fo .noino ehT umixam m elbatekram dleiy saw ac deriuq morf ylluf detagirri tnemtaert (T1) w cih h si 39.91 ah/t dna ht e muminim elbatekram yi dle saw deniatbo morf 3T ( %05 of CWR cifed it guorht tuoh org w ni g osaes n) hcihw si 01 13. t/ .ah 01T ( %05 fo C WR de ticif ta im d egats ) wohs ed eht muminim sevrah t xedni ( 6.0 8) na d 4T dna 7T ( %52 fo CWR ticifed ta ni laiti dna etal segats itcepser ev yl ) ewohs d eht mumixam .xedni hT e tsewol IH i detacidn taht retaw ticifed ta dim ts ega sesuac hgih leiy d .noitcuder ehT ma umix m porc retaw dorp u ytivitc ( 9.4 8 m/gk 3 ) saw bo s vre ed ta 3T ( 05 % fo CW R ticifed tuohguorht worg i gn osaes n) dna eht muminim ( 22.3 m/gk 3 ) saw o devresb ta 01T (50% o f CWR ticifed ta dim ts age). ehT tsegral retaw gnivas htiw s tnacifingi dleiy noitcuder aw s deniatbo ta 3T .Y dlei esnopser rotcaf ( yk ) acidni t de taht noino saw evitisnes dleiy( uder ced) rof retaw sserts ta tnempoleved dna dim htworg st .sega %05 fo CWR d ticife ta eno doirep serts s stnemtaert dewohs k 1>y , hcihw setacidni eht s ne s ytiviti fo eht o noin porc f ro hgih retaw sserts . ehT cimonoce sisylana i detacidn taht eht ixam m mu lanigram etar fo nruter saw deniatbo ta T 11 (50% fo CWR d ticife ta eht etal gats e) htiw a ten emocni fo 077,801 ah/rrib dna a lanigram tar e fo nruter 9.2765 .% ehT r ,erofe 11T ( %05 fo CWR ticifed ta etal s egat ) is yllacimonoce lbaiv e metsys fo noino noitcudorp htiw ingis f tnaci etaw r gnivas dna fi sremraf ta siht latnemirepxe etis pa e
PERFORMANCE EVALUATION OF TSILWE SMALL SCALE IRRIGATION SCHEME IN GABA CATCHMENT ENDERTA DISTRICT, TIGRAY REGION
(Hawassa University, 2017-07-12) MAMUYE ADISU YIHDEGO
This research (study) was conducted to evaluate the performance of Tsilwe SSIS in Enderta district, Tigray Regional State, Ethiopia. The performance of Tsilwe SSIS was not appraised since its operation. Therefore, this study was carried out to evaluate the performance of Tsilwe SSIS using Internal and external performance indicators. This study used primary and secondary data for assessing the irrigation performance. The primary data collected includes field observation, soil samples to characterize the soil in terms of physical characteristics and discharge measurement at main and field canals. Secondary data collected were total yield, area irrigated, crop type, and climate data. CROPWAT 8.0 model was used to calculate ETo and the crop water requirement. The analysis of internal performance indicators showed that the conveyance, application, storage, overall irrigation efficiencies and distribution uniformity were calculated and the results were 93.5%, 71.1 %, 60.2 %, 66.6 % and 87.2 % respectively. The analysis of water related indicators such as RWS and RIS were found to be 0.88 and 0.85 respectively. Since value of RWS and RIS is less than one this indicated that the total water supply is not enough to meet the crop demand and the WDC for Tsilwe irrigation system was calculated as 0.7, since this is less than unit that indicates the canal capacity is insufficient to get the peak consumptive requirement. Agricultural related indicators such as output per unit irrigated area is 153958.6 birr/ha and the output per unit command area is 95860.99 birr/ha. Water productivity indicators such as, Output per unit water consumed and Output per unit irrigation water supplied are 42.2 birr/m3 and 1.83 birr/m3 in TSSI scheme respectively. Based on the results obtained can be concluded that the water related indicators results were below the standard while the agriculture production indicators are found to be reasonable
COMPARATIVE PERFORMANCE ASSESSMENT OF MOJO ASHA AND ADANO SMALL SCALE IRRIGATION SCHEMES IN EAST HARARGHE ZONE, OROMIA REGION
(Hawassa University, 2017-08-06) EBSA MUSTEFA HAKIM
This study attempts to assess and cross-compare the performance of two small-scale irrigation schemes found in Oromia regional state namely, Mojo Asha and Adano irrigation schemes using comparative indicators. After collection of the valuable data from various sources, data analysis techniques were implemented for evaluating their performance using selected performance indicators such as conveyance efficiency, Application efficiency, system efficiency, water productivity and land productivity. The results showed that the average conveyance efficiencies of the two schemes were 83.41 % and 76.78 % at Mojo Asha and Adano respectively. It was lower at Adano than Mojo Asha scheme due to poor water management and irrigation structures’ deterioration. The maximum value of application efficiency found in downstream field of Mojo Asha scheme were 65.43 % and the minimum value was found in the Adano scheme at upstream field 40.45 % due to much amount of water was applied to the field without considering water requirement. The results of water use performance also indicated that the ratio of annual relative water supply were1.09 and 1.19 at Mojo Aasha and Adano schemes respectively, and ratio of annual relative irrigation supply were 1.12 and 1.27 at Mojo Aasha and Adano schemes respectively. The result indicated that water distribution is not tightly related to crop water demand or applying more than the demand. From analysis of agricultural performance the output results showed that the outputs per unit irrigation supply were 8.62 and 7.92 Birr/m3 at Mojo Asha and Adano schemes respectively. Whereas output per unit irrigation delivered were 10.78 and 9.70 Birr/ m3 at Mojo Asha and Adano schemes respectively. Outputs per unit command area in Birr/ha were 82501 and 96750 at Mojo Asha and Adano scheme respectively. Outputs per unit irrigated cropped area in Birr/ha were 55237 and 56437.5 at Mojo Asha and Adano schemes respectively. In case of water productivity Mojo Asha scheme was performing better than Adano scheme due to more productive use of irrigation water while land productivity was performing better at Adano than Mojo Asha scheme due to more intensive irrigation and better investment. Generally evaluation results of different indicators give information of performance level of the schemes that enables to transfer best practice to propose improvement measures.
UNBOUND AGGREGATEBASE COURSE CONSTRUCTION PRACTICES IN RELATIONTO PAVEMENTQUALITY IN HAWASSACITY
(Hawassa University, 2017-08-07) YOSEF ARAGAWLIDETE
Sub-standard quality unbound aggregate base course layers are prevalent in Hawassa city with the major cause often placed on inadequate construction practices. In this study, unbound aggregate base course construction practices in Hawassa city were investigated. The objective was to relate the potential effect of the practices on pavement quality. Data and information on unbound aggregate base course construction practices were collected through a questionnaire survey and observation of practices at a number of sites where base course layer construction works were on-going. In addition, laboratory and field tests on base course aggregates and base course layers respectively, were carried out on selected road construction projects. The results indicated that unbound aggregate base course construction practices in City do not exhibit existing advancements within the road paving industry and are partly to blame for the quality deficiencies associated with road pavements. Several benefits of current advances in the unbound aggregate base course construction such as the use of either a batch or a continuous type mixing plant, self-propelled paving machine (Paver), material transfer vehicles, stringent quality control and proper material selection, handling and storage at all stages were not appropriated. More importantly, the absence of strict follow-up and supervision for rejecting segregated and sub-standard pavement sections was the main factor worsening the problem. In principle, absence of strict supervision and adherence to the standards allows poor construction practices to prevail and provide no inspiration for contractors to pursue high construction quality because doing so entails extra cost and contractors do not suffer penalties for substandard works. Therefore, to improve the city’s road pavement construction practices and hence to improve the quality and durability of road pavements in Hawassa, strict follow-up and supervision for road construction, adherence to the standards, improving the capacity of contractors and adoption of innovative performance based contracting arrangements are necessary
PERFORMANCE EVALUATION OF FURROW IRRIGATION IN BELLES SUGAR DEVELOPMENT PROJECT SUGARCANE FARM LEVEL, ETHIOPIA
(Hawassa University, 2017-08-12) ADUGNAW ASEFAW NIGATU
Evaluation of farm irrigation system plays a fundamental role in improving surface irrigation and in providing information used to advice irrigators how to improve their system operation. Furrow irrigation is one of the common methods of applying water to sugarcane at Belles sugar development project Sugarcane Plantation. The plantation is facing problems with respect to irrigation water management. This study was initiated with the objectives of evaluating the performance of furrow irrigation system at a farm level. To evaluate the performance of furrow irrigation system, a soil laboratory and field measurements (field layout, furrow geometry, time of cutoff, discharge) are made. The soil infiltration parameters „a‟, „k‟ and „fo‟ for each irrigation event are determined based on a two point approximation to volume balance method that incorporated modified Kostiakove Lewis infiltration function. Statically comparison of models outcome found the Win SRFR simulated model values provides good fitter than the SIRMOD simulation values to the estimated values. The analyses of the performance of the furrow irrigation in terms of application efficiency (Ea), distribution efficiency (Du), storage efficiency tail water Ratio (TWR), and Deep Percolation (DP) were done and found to be, the average application efficiency 62.1%, 65.3% and 68.5% for SIRMOD, estimated and WinSRFR simulated values; distribution efficiency 90.4%, 92.4% and 95.5% for estimated, SIRMOD and WinSRFR simulated value; storage efficiency 24.1%, 26.4% and 32.8% for SIRMOD, WinSRFR simulated and estimated values; TWR 31.2%, 34.2% and 37.9% for WinSRFR, estimated and SIRMOD simulated values, respectively and deep percolation ratio for all estimation is null. From the sensitivity analysis furrow slopes are higher sensitive than other parameters on influencing the application efficiency. The effects of furrow lengths are highly influencing on TWR. The effect of discharge influence on the storage efficiency also high with compared to others whereas the time of cutoff found affect the distribution efficiency.
COMPARATIVE PERFORMANCE ASSESSMENT OF MOJO ASHA AND ADANO SMALL SCALE IRRIGATION SCHEMES IN EAST HARARGHE ZONE, OROMIA REGION
(Hawassa University, 2017-08-24) EBSA MUSTEFA HAKIM
This study attempts to assess and cross-compare the performance of two small-scale irrigation schemes found in Oromia regional state namely, Mojo Asha and Adano irrigation schemes using comparative indicators. After collection of the valuable data from various sources, data analysis techniques were implemented for evaluating their performance using selected performance indicators such as conveyance efficiency, Application efficiency, system efficiency, water productivity and land productivity. The results showed that the average conveyance efficiencies of the two schemes were 83.41 % and 76.78 % at Mojo Asha and Adano respectively. It was lower at Adano than Mojo Asha scheme due to poor water management and irrigation structures’ deterioration. The maximum value of application efficiency found in downstream field of Mojo Asha scheme were 65.43 % and the minimum value was found in the Adano scheme at upstream field 40.45 % due to much amount of water was applied to the field without considering water requirement. The results of water use performance also indicated that the ratio of annual relative water supply were1.09 and 1.19 at Mojo Aasha and Adano schemes respectively, and ratio of annual relative irrigation supply were 1.12 and 1.27 at Mojo Aasha and Adano schemes respectively. The result indicated that water distribution is not tightly related to crop water demand or applying more than the demand. From analysis of agricultural performance the output results showed that the outputs per unit irrigation supply were 8.62 and 7.92 Birr/m3 at Mojo Asha and Adano schemes respectively. Whereas output per unit irrigation delivered were 10.78 and 9.70 Birr/ m3 at Mojo Asha and Adano schemes respectively. Outputs per unit command area in Birr/ha were 82501 and 96750 at Mojo Asha and Adano scheme respectively. Outputs per unit irrigated cropped area in Birr/ha were 55237 and 56437.5 at Mojo Asha and Adano schemes respectively. In case of water productivity Mojo Asha scheme was performing better than Adano scheme due to more productive use of irrigation water while land productivity was performing better at Adano than Mojo Asha scheme due to more intensive irrigation and better investment. Generally evaluation results of different indicators give information of performance level of the schemes that enables to transfer best practice to propose improvement measures.
IMPACTS OF CLIMATE CHANGE ON RAINFED MAIZE PRODUCTION IN RIFT VALLEY LAKES BASINS OF ETHIOPIA; HAWASSA AS CASE STUDY
(Hawassa University, 2017-10-07) KINDE NEGESSA DISASA
Agriculture is mainstay of Ethiopian economy. Developing country like Ethiopia suffers from effects of climate change, due to their limited economic capability to build irrigation projects to reduce climate change impact on crop production. This study evaluates climate change impact on rainfed maize production in rift valley lakes basins of Ethiopia. First, outputs of 15 General Circulation Models (GCMs) under two emission scenarios (SRA1B and SRB1) are statistically downscaled by using LARS-WG software. Probability assessment of bounded range with known distributions is used to deal with the uncertainties of GCMs’ outputs. These GCMs outputs are weighted by considering the ability of each model to simulate historical records. The study result indicates that LARS-WG 5.5 model is more uncertain to simulate future mean rainfall than generating maximum and minimum mean temperatures hereby GCMs weight difference for rainfall mean is 0.83 whereas weight difference for minimum and maximum mean temperatures is 0.09. AquaCrop, version 4 developed by FAO that simulates the crop yield response to water deficit conditions, is employed to assess potential rainfed maize production in the study area with and without climate change. The study results indicate minimum and maximum temperatures absolute increase in the range of 0.34 0 C to 0.580 C, 0.940 C to 1.80 C and 1.420 C to 3.20 C and 0.320 C to 0.560 C, 0.910 C to 1.80 C and 1.340 C to 3.0350 C respectively in the near-term (2020s), mid-term (2055s) and long-term (2090s) under both emission scenarios. The expected percentage change of rainfall during these three time periods considering this GCMs weight difference into account ranges from -2.3 to 7%, 0.375 to 15.83% and 2.625 to 31.1%. Maize yields are expected to increase with the range of 3.63% to 7%, 5.39% to 14.08%, and 6.83% to 15.61%, during the same time periods. Unlike many studies in the world this study result show that maize yield increased in coming three time periods under both emission scenarios. Due to rainfall increase with temperature increase maize yield is expected to increase in future for this study area by using only rainfall. In conclusion, the results indicate that climate change will respond positively to climate change impact on maize yield production for this district if all field management, soil fertility and crop variety improved; but since there is rainfall variability among the seasons planting date should be scheduled well to combat water stress on crops
W YTIVITCUDORP DNA DLEIY ER S NOP SE FO NOINO DNU RE LLUF DNA ICIFED T NOITAGIRRI NI W RETA S ECRAC AERA , M OKERA ,ADEROW ET IPOIH A
(Hawassa University, 2017-10-11) KE ARD LA AW BELA UH SSEN
F retaw si acs r ec in ynam strap fo ht e dlrow dna nimoceb g a labolg a .adneg erutlucirgA si eht tsegral gnoma s tce o sr hcihw era snoc u gnim eguh hserf retaw . ehT sevitcejbo fo siht duts y erew ot evorpmi larutlucirga retaw ytivitcudorp a dn etagitsevni eht dleiy esnopser fo noino porc ot retaw .ticifed ehT dohtem deyolpme pmocne a sess dleif tnemirepxe ni dezimodnar telpmoc e kcolb ngised ( BCR D) htiw nevele stnemtaert na d eerht .snoitacilper ehT stnemtaert :erew lluf noitagirri ( %0 ticifed sa lortnoc ), %52 fo CWR ticifed tuohguorht org wing %05,nosaes fo CW R ticifed tuohguorht worg i gn ,nosaes dna eno p doire ticifed stnemtaert (25% dna %05 fo CW R ticifed ta in laiti , ,tnempoleved dim dna etal s egat s). ehT xe p tnemire saw deirrac tuo ta okeram aderow nrehtuos .aipoihtE stluseR dewohs taht secnereffid ni rri i tag noi retaw tnuoma yltnacifingis tceffa yponac ,revoc blub dleiy dna a evob dnuorg ssamoib fo .noino ehT umixam m elbatekram dleiy saw ac deriuq morf ylluf detagirri tnemtaert (T1) w cih h si 39.91 ah/t dna ht e muminim elbatekram yi dle saw deniatbo morf 3T ( %05 of CWR cifed it guorht tuoh org w ni g osaes n) hcihw si 01 13. t/ .ah 01T ( %05 fo C WR de ticif ta im d egats ) wohs ed eht muminim sevrah t xedni ( 6.0 8) na d 4T dna 7T ( %52 fo CWR ticifed ta ni laiti dna etal segats itcepser ev yl ) ewohs d eht mumixam .xedni hT e tsewol IH i detacidn taht retaw ticifed ta dim ts ega sesuac hgih leiy d .noitcuder ehT ma umix m porc retaw dorp u ytivitc ( 9.4 8 m/gk 3 ) saw bo s vre ed ta 3T ( 05 % fo CW R ticifed tuohguorht worg i gn osaes n) dna eht muminim ( 22.3 m/gk 3 ) saw o devresb ta 01T (50% o f CWR ticifed ta dim ts age). ehT tsegral retaw gnivas htiw s tnacifingi dleiy noitcuder aw s deniatbo ta 3T .Y dlei esnopser rotcaf ( yk ) acidni t de taht noino saw evitisnes dleiy( uder ced) rof retaw sserts ta tnempoleved dna dim htworg st .sega %05 fo CWR d ticife ta eno doirep serts s stnemtaert dewohs k 1>y , hcihw setacidni eht s ne s ytiviti fo eht o noin porc f ro hgih retaw sserts . ehT cimonoce sisylana i detacidn taht eht ixam m mu lanigram etar fo nruter saw deniatbo ta T 11 (50% fo CWR d ticife ta eht etal gats e) htiw a ten emocni fo 077,801 ah/rrib dna a lanigram tar e fo nruter 9.2765 .% ehT r ,erofe 11T ( %05 fo CWR ticifed ta etal s egat ) is yllacimonoce lbaiv e metsys fo noino noitcudorp htiw ingis f tnaci etaw r gnivas dna fi sremraf ta siht latnemirepxe etis pa e
A CASE STUDY OF MAI-SHAWSH AND MIDMAR SMALL SCALE IRRIGATION SCHEMES, IN MEREB SUB-BASIN, NORTH ETHIOPIA
(Hawassa University, 2017-10-16) GUESH HAGOS ASRESU
This study tries to evaluate the performance of small scale irrigation schemes using comparative indicators at Maishawsh and Midmar schemes, Mereb Sub basin, North Ethiopia. This study area has poor water management practice and not evaluated before using comparative performance indicators. To address the objectives of irrigation water use efficiency and on-field irrigation management performance of this study was field measurements related to canal discharge, moisture content determination of the soils, measurement of depth of water applied to the fields using two inches parshal flume, group discussion and informant interview to establish the cost of production and the price produced. The result of this study revealed that, the conveyance efficiency for Maishawsh scheme was 98.95%, 91.03%, and 75.21%, respectively for main lined, secondary lined and tertiary unlined canals of the scheme, and for Midmar scheme, it was 76.89% which was an earthen canal. The computed application, storage, distribution and overall scheme efficiency values are 60.8, 64.2, 93.40 and 46.7% for Midmar while they are 56.8, 70, 94.2 and 42.7% for Maishawsh schemes, respectively. The comparative indicators of agricultural outputs such as land productivity measured as outputs per unit command area and outputs per unit irrigated area are 3461.58 and 3512.8 US$/ha for Midmar while 3120.91 and 3032.46 US$/ha for Maishawsh respectively. The water indicators such as output per unit irrigation supply and Output per water consumed are 0.36 and 0.61 for Midmar while they are 0.25 and 0.54 US$/m3 for Maishawsh schemes respectively. The water supply indicators measured by, relative water supply and relative irrigation supply gave 1.8 and 1.85 for Midmar while they are 2.29 and 2.37 for Maishawsh schemes respectively. This implied that the amount of water supplied was sufficient for the water demand of both schemes. The original irrigable and command area was declined by 2% from the actual irrigated area in Midmar scheme. However, the actual irrigated area was expanded by 3% and 6% from original irrigable and command area in Maishawsh scheme respectively. The financial indicators measured by gross return on investment and financial self sufficiency for Midmar are 91.5 and 69% while they are 91 and 77% for Maishawsh respectively. Based on this result, Midmar irrigation scheme was slightly better than Maishawsh, the reason might be good water management at field level and Midmar water users pay for what they have consumed
MPACTS OF CLIMATE CHANGE ON RAINFED MAIZE PRODUCTION IN RIFT VALLEY LAKES BASINS OF ETHIOPIA; HAWASSA AS CASE STUDY
(Hawassa University, 2017-10-18) KINDE NEGESSA DISASA
Agriculture is mainstay of Ethiopian economy. Developing country like Ethiopia suffers from effects of climate change, due to their limited economic capability to build irrigation projects to reduce climate change impact on crop production. This study evaluates climate change impact on rainfed maize production in rift valley lakes basins of Ethiopia. First, outputs of 15 General Circulation Models (GCMs) under two emission scenarios (SRA1B and SRB1) are statistically downscaled by using LARS-WG software. Probability assessment of bounded range with known distributions is used to deal with the uncertainties of GCMs’ outputs. These GCMs outputs are weighted by considering the ability of each model to simulate historical records. The study result indicates that LARS-WG 5.5 model is more uncertain to simulate future mean rainfall than generating maximum and minimum mean temperatures hereby GCMs weight difference for rainfall mean is 0.83 whereas weight difference for minimum and maximum mean temperatures is 0.09. AquaCrop, version 4 developed by FAO that simulates the crop yield response to water deficit conditions, is employed to assess potential rainfed maize production in the study area with and without climate change. The study results indicate minimum and maximum temperatures absolute increase in the range of 0.34 0 C to 0.580 C, 0.940 C to 1.80 C and 1.420 C to 3.20 C and 0.320 C to 0.560 C, 0.910 C to 1.80 C and 1.340 C to 3.0350 C respectively in the near-term (2020s), mid-term (2055s) and long-term (2090s) under both emission scenarios. The expected percentage change of rainfall during these three time periods considering this GCMs weight difference into account ranges from -2.3 to 7%, 0.375 to 15.83% and 2.625 to 31.1%. Maize yields are expected to increase with the range of 3.63% to 7%, 5.39% to 14.08%, and 6.83% to 15.61%, during the same time periods. Unlike many studies in the world this study result show that maize yield increased in coming three time periods under both emission scenarios. Due to rainfall increase with temperature increase maize yield is expected to increase in future for this study area by using only rainfall. In conclusion, the results indicate that climate change will respond positively to climate change impact on maize yield production for this district if all field management, soil fertility and crop variety improved; but since there is rainfall variability among the seasons planting date should be scheduled well to combat water stress on crops
PERFORMANCE EVALUATION OF TSILWE SMALL SCALE IRRIGATION SCHEME IN GABA CATCHMENT ENDERTA DISTRICT, TIGRAY REGION
(Hawassa University, 2017-10-21) MAMUYE ADISU YIHDEGO
This research (study) was conducted to evaluate the performance of Tsilwe SSIS in Enderta district, Tigray Regional State, Ethiopia. The performance of Tsilwe SSIS was not appraised since its operation. Therefore, this study was carried out to evaluate the performance of Tsilwe SSIS using Internal and external performance indicators. This study used primary and secondary data for assessing the irrigation performance. The primary data collected includes field observation, soil samples to characterize the soil in terms of physical characteristics and discharge measurement at main and field canals. Secondary data collected were total yield, area irrigated, crop type, and climate data. CROPWAT 8.0 model was used to calculate ETo and the crop water requirement. The analysis of internal performance indicators showed that the conveyance, application, storage, overall irrigation efficiencies and distribution uniformity were calculated and the results were 93.5%, 71.1 %, 60.2 %, 66.6 % and 87.2 % respectively. The analysis of water related indicators such as RWS and RIS were found to be 0.88 and 0.85 respectively. Since value of RWS and RIS is less than one this indicated that the total water supply is not enough to meet the crop demand and the WDC for Tsilwe irrigation system was calculated as 0.7, since this is less than unit that indicates the canal capacity is insufficient to get the peak consumptive requirement. Agricultural related indicators such as output per unit irrigated area is 153958.6 birr/ha and the output per unit command area is 95860.99 birr/ha. Water productivity indicators such as, Output per unit water consumed and Output per unit irrigation water supplied are 42.2 birr/m3 and 1.83 birr/m3 in TSSI scheme respectively. Based on the results obtained can be concluded that the water related indicators results were below the standard while the agriculture production indicators are found to be reasonable
HYDRAULIC MODELING AND FLOOD MAPPING OF HAROSHA RIVER WITH HEC-RAS AND HEC-GeoRAS MODELS IN TIGRAY, ETHIOPIA
(Hawassa University, 2017-10-27) MULUGETA TAREKE ABEBE
The Harosha river catchment is found in Tigray region in Raya Valley. This study area is surrounded by Waja and Tumuga catchment in the south and Harosha, Limeat and Harle catchment in the North and also it is the upper south part of the Raya valley catchment. The area is also dominated by undulating terrain with relatively steep to moderately steep and flatter slopes in the downstream of the catchment. Harosha flood plain has been vulnerable to high flooding from rainfall during rainy season. Also the main causes of these damages are land use changes from years to years and the main objective of this study is to estimate peak flood for various return period and prepare flood inundation mapping that can be used as decision support system for future intervention. The data used for this study was annual daily maximum rainfall, DEM, land use land cover map, and soil map and the flood frequency analysis of annual maximum daily rainfall was analyzed. The SCS rain fall-runoff method, HEC-RAS, HEC-GeoRAS and ArcGIS environment are used to determine the peak flood for different return periods. The simulation result for return period of 5, 10, 25, 50 and 100 year floods magnitude are 347.4, 383.7, 420.8, 443.6 and 463.1m 3 /s respectively. The maximum flood hazard and flow depth maps for a return periods of 5, 10, 25, 50 and 100 year are 84.6 and 3.36; 86.1 and 3.84; 86.9 and 4.35; 87.1 and 4.91; and 87.7 hectare and 5.89 m respectively with a maximum velocity of 4.6 m/s.
PERFORMANCE EVALUATION OF SANKO SMALL SCALE IRRIGATION SCHEME AT BASKETO SPECIAL WOREDA IN SNNPR, ETHIOPIA
(Hawassa University, 2018-04-06) MARKOS HABTEWOLD ADEBO
This study was conducted to evaluate the performance of Sanko small scale irrigation scheme at Basketo Special Woreda, South Nation Nationalities Peoples Regional states. The irrigation scheme includes command area of 120 ha and 600 beneficiaries. To achieve the objective of the study; primary and secondary data were collected. The irrigation scheme was evaluated using minimum sets of internal and external comparative performance indicators which include agricultural, water use, physical and economic performance indicators. In order to evaluate the irrigation water use efficiency of farmers at field level, nine farmer fields were selected from the irrigation scheme in relation to their location (from the head, middle and tail end water users).The internal performance indicators which include conveyance, application, storage, deep percolation ratio and overall irrigation efficiency were used to check the performance of the irrigation scheme. From the analyses of the internal performance indicators, the conveyance efficiencies was found to be 69.3% and application efficiencies were found to be 61.6%, 63.4% and 46.5% at head, middle and tail end part of the irrigation scheme respectively. Average field application efficiency through out of the Sanko irrigation scheme was 57.2%. A deep percolation ratio in the same order of the scheme was found to be 42.8% and Storage efficiencies of 78.5%. Generally overall scheme efficiency of Sanko irrigation scheme was 39.6%. From the evaluation of external comparative indicators, the outputs per cropped area were found as 84,706 Birr ha-1 , 220,690 Birr ha-1 and 69,686.4 Birr ha-1 at head, middle and tail end part of irrigation scheme respectively and the value of the outputs per command area of scheme was 15,003,276 Birr per command area. The output per unit irrigation supply of irrigation scheme was 13.5 Birr m-3 , 33.95 Birr m-3 and 22.12 Birr m-3 at head, middle and tail end part of the scheme respectively. The water use performance of the scheme, like relative water supply and relative irrigation supply were found as 1.28 which was the same since there was no rainfall during study period. The irrigation ratio of the Sanko irrigation scheme was found to be 1.00 which means 100% of command area was under irrigation and additional 25ha was on the construction during study period. Water delivery performance indicator which includes adequacy, efficiency, dependability, and equity from these measures only adequacy was fair and good at head and middle part of irrigation scheme according to standard values but all of other measures were poor according to standard values. In general, based on the evaluation carried out; Sanko irrigation scheme at middle part was performed better than upper head and lower part of the scheme. But there is still a room for improvement of the performance at all of the system level. Therefore to reduce over and under irrigate farmers should get awareness how to use, when to use and how much water used on their fields.
EFFECTS OF SALINE WATER AND IRRIGATION INTERVAL ON SOYBEAN (GLYCINE MAX) YIELD AND ALTERING SOIL PHYSICO-CHEMICAL PROPERTIES
(Hawassa University, 2018-07-06) ATALEL AWOKE
The declining availability of fresh water has become a worldwide problem, which maintains the development of alternative, secondary quality water resources for agricultural use. Several studies recommend that the need of attention for selected crops that can tolerate water and salinity stresses when saline water is used for irrigation. In this study, the effects of different irrigation intervals and salinity levels of irrigation water on Soybean yield and their impacts on soil physico-chemical properties were investigated using three irrigation intervals (I1 =3days, I2= 4days and I3= 5 days) with four salinity levels (S1= 4dS m-1 , 5dS m-1 and 6 dS m- 1 ) in a factorial combination using CRD with three replications. The result showed that salinity, irrigation interval and their interaction had shown highly significance effects (p<0.001) on number of pod per plant, number of seed per plant and grain yield of Soybean. The highest number of pod number (88.33), grain yield (2.31ton/ha) and number of seed per plant (172.33) was recorded from Soybean which was irrigated with the first salinity level, i.e. fresh water (S1) with irrigation interval of (3 days), S1I1;while the lowest pod number per plant (6.67), number of seed per plant (12.67) and minimum grain yield (0.034 ton/ha) were obtained from Soybean irrigated by salinity level four (S4) with 5 days irrigation interval (S4I3).Statistical analysis showed that salinity ,irrigation interval and their interaction showed highly significance effects (p<0.001)on electrical conductivity of soil. Irrigation with highest salinity level (S4) with five days of irrigation interval resulted in the salt accumulation in the root zone from 0.41 μS m -1 (before sowing) up to 13.73 μS/cm at the end of growing period and exchangeable Sodium of 0.2 cmol/Kg was found before sowing while 0.82cmol/kg was found after harvesting. Therefore, based on soil salinity and crop yield, irrigation interval of 3 days at lower levels of irrigation water salinities (up to 3 dS m-1 ) is suitable for soybean production in the study area. The study also showed that salinity and irrigation interval significantly affected the soil nutrients (p< 0.001) despite their interaction were not significantly affected on soil nutrients. Increasing the concentration of salt in irrigation water reduce availability of nutrients in the soil. Soil which was irrigated by salinity level four (S4=6dS/m) had lowest Organic Matter, Organic Carbon, Nitrogen (N), Phosphorus (P) and Potassium (K) content. Highest Organic Matter, Organic Carbon, N and P content were observed at soils which were irrigated by fresh water. This indicates that there is a need for giving attention for management of soil besides achieving Soybean yield production when saline water is used for irrigation.
PERFORMANCE EVALUATION OF WOSHA AND WERKA IRRIGATION SCHEMES IN WONDO GENET DISTRICT, SNNPRS, ETHIOPIA
(Hawassa University, 2018-10-07) HENOK TESFAYE CHARINET
Expanding efficient irrigation development on various scales is one of the best alternatives to provide reliable and sustainable food security. However, many irrigation schemes in developing countries in general and particularly in Ethiopia are performance below capacity. Performance evaluation of irrigation schemes plays a fundamental role in improving irrigation system of a scheme by identifying where the critical problems occurred. Evaluation of irrigation schemes carried out at Wondo Genet SNNPRS, Ethiopia. The primary objective of evaluating Wosha and Werka irrigation schemes using internal and external indicators were to evaluate their performance and suggest possible interventions to enhance their capacity. Internal indicators including conveyance, application, water storage, water distribution uniformity efficiency, and deep percolation ratio were used at the head, middle and tail reach of each scheme. Moreover, external indicators of agriculture output, water supply, water delivery capacity and physical indicator were used for evaluating the schemes. The results showed that the conveyance, application, storage, distribution efficiency of 55.6, 48.2, 89.8 and 91.7%, respectively were found at Wosha irrigation scheme whereas 43.0, 59.0, 87.2 and 91.4%, respectively at Werka irrigation scheme. The agricultural output performance such as OPUIA, OPUCA, OPUIS, and OPUWC were 4213.97 US$/ha, 8732.29 US$/ha, 1.18 and 0.32, respectively at Wosha irrigation scheme and 5840.34, 8534.19, 1.77 and 0.42 respectively for Werka irrigation scheme. Water supply indicators such as RIS and RWS were 0.64 and 0.71, respectively for Wosha 0.48 and 0.55, respectively for Werka irrigation scheme. The result indicates that water delivery capacity of Wosha and Werka irrigation schemes were 1.56 and 1.32, respectively. Physical indicators revealed that irrigation ratio of 0.89 and 0.78 and sustainability of irrigated area of 2.07, and 1.46 were found at Wosha and Werka irrigation schemes. Among the internal indicators, application efficiency was very low especially at Wosha irrigation scheme due to higher water loss through deep percolation. The overall efficiency was also below the desired level, where 26.8 and 25.4 %, respectively realized at Wosha and Werka irrigation schemes. Based on the above observation, adoption of water saving practices such as deficit irrigation, surge and cutoff application to improving application, conveyance and distribution systems can enhance crop productivity per unit irrigation wate
EVALUATION OF ALTERNATE, FIXED AND CONVENTIONAL FURROW IRRIGATION SYSTEMS WITH DIFFERENT WATER APPLICATION LEVELS ON ONION PRODUCTION IN DUBTI, AFAR
(Hawassa University, 2018-10-07) ZINABU AKELE DERBEW
Water scarcity is a major constraint for the production of food required in arid and semi-arid areas. Therefore, deficit irrigation and application of irrigation systems are important concerns to improve water productivity and sustained production in the areas with water shortage like lower Awash valley. A field experiment was conducted with the objective of evaluating the performance of alternate, fixed and conventional furrow irrigation systems under different water application levels on onion yield in Dubti, lower Awash basin. The treatments were three deficit irrigation levels of 50%, 75% and 100% of crop water requirements with three furrow irrigation systems of conventional, alternate and fixed furrow were laid out a factorial random complete block design (RCBD) with three replications. Data on plant growth and bulb yield were collected and analyzed. The result of the study indicated highly significant (α ≤ 0.0) differences for yield and WUE’s. The highest bulb yield of 25.46 ton/ha was obtained at 100% ETC with conventional furrow irrigation method. AFI 50% ETC water application level gave the highest water use efficiency. In contrast, the minimum water use efficiency was recorded with conventional furrow method with 100% water application level. CFI 100%, CFI 75%, and AFI 50% were not shown significant difference on yield which is 25.46 ton/ha, 24.88 ton/ha, and 24.54 ton/ha respectively, besides better water use efficiency of 8.39 kg/m3 was recorded from AFI 100%. In relative to the control CFI 100%, applying AFI 100% able to increase 0.868 ha net additional irrigable land per each hectare. Therefore, it can be decided that Alternative furrow irrigation with 100% ETC increased water use efficiency and can solve a problem of water shortage by improving WUE without significant reduction of yield.
PERFORMANCE EVALUATION OF SANKO SMALL SCALE IRRIGATION SCHEME AT BASKETO SPECIAL WOREDA IN SNNPR, ETHIOPIA
(Hawassa University, 2018-10-12) MARKOS HABTEWOLD ADEBO
This study was conducted to evaluate the performance of Sanko small scale irrigation scheme at Basketo Special Woreda, South Nation Nationalities Peoples Regional states. The irrigation scheme includes command area of 120 ha and 600 beneficiaries. To achieve the objective of the study; primary and secondary data were collected. The irrigation scheme was evaluated using minimum sets of internal and external comparative performance indicators which include agricultural, water use, physical and economic performance indicators. In order to evaluate the irrigation water use efficiency of farmers at field level, nine farmer fields were selected from the irrigation scheme in relation to their location (from the head, middle and tail end water users).The internal performance indicators which include conveyance, application, storage, deep percolation ratio and overall irrigation efficiency were used to check the performance of the irrigation scheme. From the analyses of the internal performance indicators, the conveyance efficiencies was found to be 69.3% and application efficiencies were found to be 61.6%, 63.4% and 46.5% at head, middle and tail end part of the irrigation scheme respectively. Average field application efficiency through out of the Sanko irrigation scheme was 57.2%. A deep percolation ratio in the same order of the scheme was found to be 42.8% and Storage efficiencies of 78.5%. Generally overall scheme efficiency of Sanko irrigation scheme was 39.6%. From the evaluation of external comparative indicators, the outputs per cropped area were found as 84,706 Birr ha-1 , 220,690 Birr ha-1 and 69,686.4 Birr ha-1 at head, middle and tail end part of irrigation scheme respectively and the value of the outputs per command area of scheme was 15,003,276 Birr per command area. The output per unit irrigation supply of irrigation scheme was 13.5 Birr m-3 , 33.95 Birr m-3 and 22.12 Birr m-3 at head, middle and tail end part of the scheme respectively. The water use performance of the scheme, like relative water supply and relative irrigation supply were found as 1.28 which was the same since there was no rainfall during study period. The irrigation ratio of the Sanko irrigation scheme was found to be 1.00 which means 100% of command area was under irrigation and additional 25ha was on the construction during study period. Water delivery performance indicator which includes adequacy, efficiency, dependability, and equity from these measures only adequacy was fair and good at head and middle part of irrigation scheme according to standard values but all of other measures were poor according to standard values. In general, based on the evaluation carried out; Sanko irrigation scheme at middle part was performed better than upper head and lower part of the scheme. But there is still a room for improvement of the performance at all of the system level. Therefore to reduce over and under irrigate farmers should get awareness how to use, when to use and how much water used on their fields.
PERFORMANCE EVALUATION OF WOSHA AND WERKA IRRIGATION SCHEMES IN WONDO GENET DISTRICT, SNNPRS, ETHIOPIA
(Hawassa University, 2018-10-21) HENOK TESFAYE CHARINET
Expanding efficient irrigation development on various scales is one of the best alternatives to provide reliable and sustainable food security. However, many irrigation schemes in developing countries in general and particularly in Ethiopia are performance below capacity. Performance evaluation of irrigation schemes plays a fundamental role in improving irrigation system of a scheme by identifying where the critical problems occurred. Evaluation of irrigation schemes carried out at Wondo Genet SNNPRS, Ethiopia. The primary objective of evaluating Wosha and Werka irrigation schemes using internal and external indicators were to evaluate their performance and suggest possible interventions to enhance their capacity. Internal indicators including conveyance, application, water storage, water distribution uniformity efficiency, and deep percolation ratio were used at the head, middle and tail reach of each scheme. Moreover, external indicators of agriculture output, water supply, water delivery capacity and physical indicator were used for evaluating the schemes. The results showed that the conveyance, application, storage, distribution efficiency of 55.6, 48.2, 89.8 and 91.7%, respectively were found at Wosha irrigation scheme whereas 43.0, 59.0, 87.2 and 91.4%, respectively at Werka irrigation scheme. The agricultural output performance such as OPUIA, OPUCA, OPUIS, and OPUWC were 4213.97 US$/ha, 8732.29 US$/ha, 1.18 and 0.32, respectively at Wosha irrigation scheme and 5840.34, 8534.19, 1.77 and 0.42 respectively for Werka irrigation scheme. Water supply indicators such as RIS and RWS were 0.64 and 0.71, respectively for Wosha 0.48 and 0.55, respectively for Werka irrigation scheme. The result indicates that water delivery capacity of Wosha and Werka irrigation schemes were 1.56 and 1.32, respectively. Physical indicators revealed that irrigation ratio of 0.89 and 0.78 and sustainability of irrigated area of 2.07, and 1.46 were found at Wosha and Werka irrigation schemes. Among the internal indicators, application efficiency was very low especially at Wosha irrigation scheme due to higher water loss through deep percolation. The overall efficiency was also below the desired level, where 26.8 and 25.4 %, respectively realized at Wosha and Werka irrigation schemes. Based on the above observation, adoption of water saving practices such as deficit irrigation, surge and cutoff application to improving application, conveyance and distribution systems can enhance crop productivity per unit irrigation water