Water Resource
Permanent URI for this collectionhttps://etd.hu.edu.et/handle/123456789/71
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Item SOIL LOSS RISK ASSESSMENT UNDER CLIMATE CHANGE AND MANAGEMENT PRACTICES: A CASE OF NERI WATERSHED, OMO-GIBE BASIN, SOUTHWESTERN ETHIOPIA(Hawassa University, 2019-10-22) ABEBE HEGANO HEMACHOSoil erosion is one of the biggest global environmental problems resulting in both on-site and off site effects. Climate change is expected to affect soil erosion based on a variety of factors, including a direct impact on soil loss by increasing precipitation amounts and erosive power. Neri watershed was chosen for this study. The objective of study is to assess soil loss risk under climate change and anticipated management practices. Revised Universal Soil Loss Equation model was applied by integrating bio physical and remote sensing data. Model parameters were computed from available data. Three Representative concentration Pathway scenarios (RCP2.6, RCP4.5 and RCP8.5) and management practices considered for estimation of annual soil loss rates. The resultant annual soil loss map under baseline condition shows the mean and total of 9.955t/ha/yr- 1 and 0.46m t/yr respectively. Estimates suggest that out of the total (46546 ha), about 32.7% % of the total area exceeded the tolerable limit and 67.3%% of the total area were below tolerable rate. The future soil loss rates are higher than the baseline period if no management actions are taken. Under no- management action scenario, the predicted the incremental rate of soil loss from (21.95%) for RCP8.5 (2051-2080) followed by 4.57% RCP4.5 (2021-2050) to insignificant decline (-0.75%) for RCP2.6 (2021-2050) compared to baseline period whereas, the other two predicted reduction. Moreover, inclusion of comprehensive management may result much higher reduction in soil loss over baseline and future condition of no action. The maximum reduction by 41.2% of its soil loss due to climate change is predicted RCP8.5 (2051-2080). The resultant soil loss map of baseline period was used in prioritization of intervention areas based on soil loss tolerance. Among eleven (11) sub-watersheds, eight and ten administrative kebeles out of nineteen are above the tolerable limit. However, watershed as planning unit, taking the proportion of soil loss to area, seven sub watersheds were identified as areas of intervention. To ensure sustainable resource use, management practice like contour cropping system complimented with terraces in agricultural fields and with giving special attention through strong policy measures to climate change, erosion minimization in non-agricultural land use classes were needed. Finaly, the study indicates a need for further study to understand the land suitability that consider the climate changeItem GROUNDWATER FLOW MODELING AND ASSESSING THE IMPACT OF FERTILIZERS ON GROUNDWATER QUALITY: THE CASE OF HORMAT-GOLINA SUB-BASIN, AWASH BASIN, ETHIOPIA(Hawassa University, 2019-10-23) MENGESHA TESFAW ABAYGroundwater is the source of water supply for different purposes including domestic, irrigation and depending on its capacity, it is suitable for industrial activities. Groundwater in many parts of the world is under risk because of increasing demands, mismanagement and contamination. All previous studies had not been explored the predicted groundwater flow dynamics in relation to climate change and anthropogenic stress, but this study has developed on the groundwater fluctuation with respect to human pressure and climate change. Visual mod flow flex 5.1 was used for simulating the groundwater flow in response to different stress periods. Groundwater flow and transport modeling in this Sub-basin have provided information about groundwater quantity as well as the quality aspect for decision makers about the groundwater accessibility. The initial head measured values in before and after irrigation season has varied to a maximum of 0.8 m. The groundwater head level in before and after irrigation season was varied from 9.3 m to 8.26 m in the Southern boundary and from 41.5 m to 38.83 m in Northwestern boundary of the Sub-basin respectively. While the predicted groundwater head and drawdown of increased pumping rate with decreased recharge rate scenario was magnify the bad effects in the Sub basin. The maximum depth of 0.27 m and 2.6 m drawdown was found in before and after irrigated season around the pumped wells respectively. The increased pumping rate with decreased recharge rate was replied to the groundwater head at the end of 2021has decreased by 2.81 min the Northwestern boundary of the Sub-basin as compared as using constant pumping rate with constant recharge rate. While decreased pumping rate with increased recharge rate was replied to the groundwater head at the end of 2021has increased by 2.23 m in the Northwestern boundary of the Sub-basin as compared as using constant pumping rate. The impacts of climate change and human pressure on groundwater have been the greatest threats in those supply wells. Decreased in pumping rate with increased recharge rate has accomplished to restore and protect the groundwater resources which is the best option for groundwater restoration and monitoring. Anthropogenic pressures including the application of fertilizers were a considerable cause of degraded groundwater quality in relation to Nitrate and Phosphate concentration with series of time. The groundwater quality has deteriorating with the applied Urea and DAP fertilizes in the selected wells of Hormat-Golina Sub-basin. Farmers have encouraged using practices that minimize the risk of groundwater pollution by carefully controlling and timing of the use of fertilizers to avoid over application.Item PERFORMANCE EVALUATION OF SMALL SCALE IRRIGATION SCHEME IN ADDIS-ALEM, SEHARTI SAMRE WOREDA, TIGRAY, ETHIOPIA.(Hawassa University, 2017-10-28) ABRHA FENTAW AKALUWater is scarce and expensive resource which needs to be utilized in a highly productive manner for agriculture. The main objective of this study was to evaluate the performance of the small scale irrigation scheme at Addis-Alem, Seharti Samre Woreda, Tigray Regional State. The importance of performance evaluation of small scale irrigation scheme mainly for advising irrigators on how to improve their system and management practice, intervention across different system levels, and to compute irrigation seasons and technologies The scheme has command area of 60 ha during the current study time and serving about 240 beneficiaries. To achieve the aim primary and secondary data were gathered. The internal and external performances using minimum sets of performance which includes agriculture water use economical, and physical performances. In order to compute the irrigation water use efficiency of farmers at field level, nine farmer fields were identified from the irrigation scheme in the relation to their location (head, middle and tail end water users). The internal process which include conveyance, application, storage, runoff, deep percolation ratio, distribution efficiencies, and overall irrigation efficiency were used to check the performance of the irrigation scheme. The results of the analyses indicate that the conveyance and application efficiencies were found to be 51.297 and 68.07% respectively. The runoff ratio of the scheme was nil as the furrows are block end type. Deep percolation ratio in the same order of the scheme was found to 31.93%. Storage efficiency was also estimated 47.69%. Further, irrigation uniformity of98.91% was attended. From the analysis of external indicators, the output per cropped area and output per command area were found as 4545.455 and 1363.636US$ha-1 respectively. The output per irrigation supply of the scheme was 0.663 US$ m-3 . Output per water consumed in the scheme was 0.974 US$ m-3 . The water use performance of the scheme was computed, water supply and relative irrigation supply were found as 7.362.The irrigation ratio of the scheme was found to be 0.30 which means about 70% of the command area is not under irrigation during the study period. In general,, the performance of Addis-Alem irrigation scheme is low . But there is still a room for improving the performance of the scheme by resizing the main canal as well as the secondary and tertiary canals which were not adequately carrying the required irrigation water