Institute of Technology
Permanent URI for this communityhttps://etd.hu.edu.et/handle/123456789/66
The Institute of Technology focuses on education, research, and innovation
in engineering, technology, and applied sciences to support sustainable development.
Browse
9 results
Search Results
Item IMPACT OF CLIMATE CHANGE ON AGRICULTURAL WATER DEMAND: THE CASE OF BILATE RIVER CATCHMENT(Hawassa University, 2019-10-27) ZEKIWOS KEBEDE KARISAClimate change has impact on agricultural water demand by affecting the different climate variables such as temperature and rainfall. This study was carried out to detect the impact of the climate change on agricultural water demand under different time horizon to prevent vulnerability to climate change at Lower Bilate River sub-basin. The data used in this study were collected from National Meteorology Agency of Ethiopia, Ministry of Water, Irrigation and Electricity. Simulated climate data were obtained with using single climate model ICHEC-EC EARTH, Precipitation and temperature time series of historical and projected time period. The scenarios used were from the Eth_CORDEX_Grids archive based on RCP4.5 and RCP8.5 Scenarios. The trend analysis for the last 32 years, indicated that the impact of the climate change to changes in long-term maximum and minimum temperature is increased by 0.0395o c and 0.1380 c respectively and changes in precipitation is by the factor of the -0.83, the prediction analysis indicates that precipitation at the study area will be -35.71% and -40.18% for the year 2048 and 2080 respectively from RCP4.5 Scenarios. Whereas, based on RCP8.5 Scenarios the change in the same order will be -48.90% and -60.11%. As a result the change is expected in agricultural water demand for the selected crops at specific study area. The average irrigated agriculture water demand of selected crops Tobacco and cotton are found to be 19.01Mm3. However, this value is not kept constant as a result of the change in climate that for future time period (2017-2048) and (2049-2080) found to be 24.01Mm3 and 25.01Mm3 respectively for RCP4.5, and in case of RCP8.5 is found to be 25.33Mm3 and 28.36Mm3 respectively. Whereas, the Rain fed agriculture water demand for the crops maize and haricot bean are estimated 87.98Mm3 at the study area. As a result, the change in climate computed as 86.65Mm3 and 104.28Mm3 for the period of 2048 and 2080 respectively for RCP4.5 Scenarios, whereas based on RCP8.5 Scenarios the change will be 100.39Mm3 and 125.42Mm3 respectivelyItem EVALUATING SEPARATE IMPACTS OF LAND USE, LAND COVER AND CLIMATE CHANGE ON STREAMFLOW IN UPPER GIDABO WATERSHED, SOUTHERN ETHIOPIA(Hawassa University, 2019-12-22) DEGEFU DOGISO BUKURELULC and climate change are two factors that produce major impacts on stream flow and separation of these impacts is important for water resources management as well as policy adaptation and planning for sustainable watershed development. This study was mainly focused on separating the combined and isolated impacts of LULC and climate change on stream flow reduction in upper Gidabo watershed, Southern Ethiopia. The hydrological modeling with the one factor at a time (OFAT) analysis was employed to separate hydrological impacts of LULCC from those of climate change. The SWAT model and MK statistics test were used for the study. SWAT was calibrated and validated in the watershed. The results confirmed that SWAT was a powerful and accurate model for the watershed. The model assessment metrics: NSE, R2 and PBIAS in the data were 0.90, 0.91 and 5% respectively for the calibration period and 0.73, 0.75 and 12.4% respectively for the validation period. After the calibration and validation of the SWAT model, four different scenarios were developed based on one factor at a time (OFAT) experiment. By comparing, the simulated mean annual stream flow components (Qsurf, Qlat and Qbase) results of S1 vs. S2, S3 and S4 for evaluating the effect of LULC and climate change and both on stream flow. The assessment of MK statistics result of climate change showed that precipitation and stream flow exhibited a downward trend and air temperature exhibited upward trends significantly from 1985 to 2016. Evaluation of LULCC from 1985 to 2016 showed that the changes in growth of agricultural land and built-up areas have increased by the annual rate of change 1.81% and 2.33% respectively whereas the mixed forest, evergreen forest and grassland has reduced by the rate of change 1.27%,1.84% and 0.30% respectively. The combined effects of LULC and climate change reduced mean annual lateral flow and base flow values by 7.17mm/yr. and 94.74mm/yr. respectively. The LULCC increased surface runoff by 38.29mm/yr. (56.5%) decreased lateral flow and base flow by 6.23mm/yr. (86.89%) and 26.48mm/yr. (27.95%) respectively while climate change decreased surface runoff, lateral flow and base flow by 29.47mm/yr. (43.5%),0.94mm/yr. (13.11%) and 68.26mm/yr. (72.05%) respectively. Generally, the climate change had the higher impact on base flow reduction while LULCC had higher impact on surface runoff increment and lateral flow reduction in the study watershed. Therefore, to mitigate the negative impacts of climate change combined with LULC change, local and national policymakers are encouraged to apply science-based watershed and land use planning and implement appropriate management approaches in the upper Gidabo watershedItem 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 DISASAAgriculture 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 cropsItem IMPACT OF CLIMATE CHANGE ON THE GROUNDWATER HYDROLOGY OF LAKE ZIWAY WATERSHED, ETHIOPIA(Hawassa University, 2022-10-23) MIERAF ABEBE DONKAClimate change poses uncertainties to the supply and management of water resources. The relationship between the changing climate variables and groundwater is more complicated and poorly understood. Groundwater resources are related to climate change through the direct interaction with surface water resources, such as lakes and rivers, and indirectly through the recharge process. The impact may be worse for developing countries like Ethiopia because of their economies are strongly dependent on basic forms of natural resources. This thesis presents the likely impact of climate change on groundwater hydrology of Lake ziway watershed located in the Rift Valley basin of Ethiopia, The RCP scenarios of types 4.5, and 8.5 were used for the climate projection from the CORDEX Africa domain from CMIP5. The RCM of RCA4 was used to generate future possible local meteorological variables in the study area. These data were used as input to the Soil and Water Assessment Tool (SWAT) model to simulate the corresponding future streamflow Variability in the Ziway watershed. SWAT-CUP, a program for calibration and uncertainty was utilized for uncertainty analysis. The two projected time periods for this study were the 2040s, and 2070s. In the Lake Ziway watershed, there exists a climate change in the study period of 1989-2019. Since, there is a significant change from the base period to the projected time periods, therefore there would exist a climate change impact for the projected time periods under both scenarios in the Lake Ziway watershed. Therefore, climate change shows a significant decreasing impact on the groundwater flow of Lake Ziway watershed, which in turn affects the level of Lake Ziway significantlyItem IMPACT OF CLIMATE CHANGE ON SURFACE WATER RESOURCE AVAILABILITY: A CASE STUDY IN WELMEL WATERSHED,GANALE-DAWA BASIN, SOUTH ETHIOPIA(Hawassa University, 2018-10-27) BERECHA DINSA CHAKAClimate change, nowadays, has significant impact on the water resource system of an area. This study was conducted for Welmel watershed, Ganale-Dawa river basin, Ethiopia, using Soil and Water Analysis Tool(SWAT) hydrological model and General Circulation Model (GCM) aiming at estimating the impact of climate change on water availability of the study area. By making proper calibration, precipitation and temperature outputs of HadCM3 coupled atmosphere-ocean GCM model for A2a (medium to high) and B2a (Medium to low) SRES emission scenarios were downscaled using the Statistical Downscaling Model (SDSM). The downscaled minimum temperature shows an increasing trend in all future time horizons for both A2 and B2 scenarios. The average annual minimum temperature will be 0.30 C change from baseline in 2020s (2014-2041).In2050s (2042-2069) of minimum temperature will be 0.65o C and also 0.63o C for A2 and B 2 scenario respectively. For the 2080s (2070-2099) periods the average annual minimum temperature will be increased by 1.3o C and 1.03o C for A2 and B2 scenario respectively. The downscaled maximum temperature scenario, on the other hand indicates that for most months there will be an increasing trend for both A2 and B2 scenario. The projected temperature in 2020s indicates that maximum temperature will rise by 0.232o C. In 2050s the increment will be 0.527o C and 0.53o C for A2 and B2 scenario respectively. The future precipitation of the study area is expected to annual average increase by 11.90% for A2a and 11.67% for B2aemission scenarios. The actual evapotranspiration will also increase by 3.64% for A2a and 3.75% for B2a respectively. The results obtained from this investigation indicate that there is significant variation in the seasonal and monthly flow. In the main rainy season (June-September) the runoff will be reduced by 12% in the 2080s. The result from synthetic (incremental) scenario also indicates that the catchment is sensitive to climate change. As much as 23% of the seasonal and annual runoff will be reduced if an increment of 2o C in temperature.Item ASSESSMENT OF CLIMATE CHANGE IMPACT ON THE WATER BALANCE OF LAKE HAWASSA WATERSHED(Hawassa University, 2023-07-25) KIFLE KARITE ONGOCHOAssessing the climatic change impact on the water balance of a watershed is vital to develop sound management plans in current and future periods. The main objective of this study was assessing the climatic change impact on the water balance of Lake Hawassa watershed. The study was focused on the projection of climate variables, assessing the historical and future water balance components, and also evaluating the impacts of climate change on the stream flows of Lake Hawassa watersde. The Soil and water Assessment Tool (SWAT) mode was used for assessing the water balance components and to evaluate the climate change impact on the stream flows of Lake Hawassa catchment. SDSM (statistical downscaling model) was used under General circulation model set up for climate modeling. The water balance components of the watershed were computed in gauged and unguaged catchments. According to the SWAT model result in the gauged catchment, the historical average annual precipitation, surface runoff and the evapotranspiration (ET) were 1068.3mm, 155.11mm and 688.3mm respectively. In 2080 for RCP 8.5 the average annual precipitation, Surface runoff and ET will be 972.15mm, 143.17mm, and 812.19mm respectively. The climate change impact on the water balance components of Lake Hawassa watershed was evaluated for RCPs 2.6, 4.5 & 8.5 emission scenarios in the three time periods (i.e. 2020 (2022- 2040), 2050(2041-2070) and 2080(2071-2099). The result from climate model showed a general increasing trend for maximum and minimum temperatures and decreasing trend for precipitation in all the three time periods for all the three emission scenarios. The impact of climate change on the seasonal stream flows of the watershed will generally increases in the Kiremt season in 2020 and 2050 for all scenarios but decreases in Bega and Belg seasons for all time period in all RCPs. The future annual precipitation, Surface runoff, lateral flow, shallow groundwater recharge and water yield will be decreased up to 9 % and 9.9 % respectively and the increase in ET may reach up to 22% at the end of 2099 for RCP_8.5. Due to climate change the future water availability will be reduced in Lake Hawassa watershed. Therefore, the design and implementation of appropriate adaptation and mitigation strategies to the watershed by the decision makers may reduce the adverse effect of climate change.Item IMPACT OF CLIMATE CHANGE ON WATER AVAILABILITY IN GIDABO WATERSHED, SOUTHERN ETHIOPIA(Hawassa University, 2020-04-24) ADANE MEZEMIR MENIGISTUClimate change significantly affects many hydrological systems, which in turn affects the water resource and the flow of rivers. The aim of this research was to investigate the impacts of future climate change on the water availability of the Gidabo watershed, which is one of the Ethiopian rift Valley sub-basins. Dynamic downscaling model was used as a representative concentration pathway (RCP) scenario for the daily precipitation, maximum and minimum temperature in the watershed. The large-scale climate variables for the RCP4.5 and RCP8.5 scenarios obtained from the Hadley Global environment model through CORDEX-Africa data outputs of HadGEM2-ES were selected under representative concentration pathway. The analysis was performed in two future projection of 2018- 2047’s and 2048-2077’s with baseline period of 1988-2017. Results showed that the average annual max/min temperature will increase by 1.23oC/1.26oC and 2.64oC/3.27oC (for 2018-2047) and by 2.57oC/0.23oC and 3.542oC/2.3oC (2048-2077) for RCP 4.5 and RCP 8.5 respectively. Average annual rainfall decreased 69.19mm and 72.3mm at RCP4.5 and RCP8.5 for (2018-2047) respectively and decreased 79.02mm and 85.12mm at RCP4.5 and RCP8.5 for (2048-2077) respectively. The SWAT hydrological model was used to simulate streamflow together with other water balance components after sensitivity analysis, calibration and validation of the model. The results indicated that water yield decrease by 21.8% and 23.9% of the rainfall in the case of RCP 4.5 and RCP 8.5 respectively. On the other hand, the trend test result on gaged data showed the presence of a no statistically significant trend in the precipitation and significant trend in the minimum temperature at most of the stations.Item 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 DISASAAgriculture 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 cropsItem IMPACT OF CLIMATE CHANGE ON THE HYDROLOGY OF UPPER BLUE NILE RIVER BASIN: A CASE STUDY IN TANA SUB-BASIN, ETHIOPIA(Hawassa University, 2020-11-06) SURAFEL ARAGAW LAMESGINClimate change is one of the serious issues in the word including developed and developing countries like Ethiopia. Tana Sub-Basin is located in the upper Blue Nile River basin . The aims of this study was to evaluate the impact of climate change on the hydrology of Upper Blue Nile River basin of Tana sub-basin in the northwest of Ethiopia. Dynamically downscaled climate model precipitation and temperature outputs were obtained from CORDEX-Africa program RCP4.5 and RCP8.5 by Regional Climate Model. The climate data has significant bias and bias correction was done by using CMhyd tool before used as input to the impact analysis. The analysis was performed in two future projection, 2020-2049 and 2050-2079 considering the reference baseline period 1988-2017 with both RCPs. Minimum temperature changes for RCP 4.5 raised by 0.26°C to 1.10°C and 0.45°C to 2.77°C, and for RCP8.5 0.15°C to 1.58°C and 1.02°C to 2.68°C Mean monthly minimum temperature change for 2020 – 2049 and 2050 – 2079. and Maximum temperature changes for RCP 4.5 and increase by 0.25°C to 1.6°C and 0.1°C to 1.91°C and for RCP 8.5 0.11°C to 1.92°C and 0.19°C to 2.17°C for 2020 – 2049 and 2050 – 2079 time periods with reference to the baseline periods respectively. And also, the mean monthly precipitation change will be increased and decreased by 2.09% to 23.95 % and 30.73% to 47.46% for both RCP4.5 and RCP8.5 scenarios respectively. The SWAT models were used to assess the streamflow response to climate change. Calibration and validation of the model output were performed by comparing simulated streamflow with observed flows from Tana Sub Basin (Blue Nile River outlet at Bahirdar gauging station) for the periods 1988-2001 for calibration and 2002-2008 for validation using SWAT-CUP(SUFI-2). The model calibration and validation result shows R2 and NSE of 0.87 and 0.84 and 0.61 and 0.6 during calibration and validation respectively. Finally, climate change impact on monthly streamflow was evaluated by relating base period stream flow with the future flows for the 2020-2049 and 2050- 2079 for both RCP4.5 and RCP8.5 scenarios. The future streamflow result shown increasing and decreasing change for both RCP4.5 and RCP8.5 scenarios. Hence, the increased and decreased stream flow in the basin may have a significant contribution for the sustainability of existed and undergoing water development projects