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

Filters

2017 - 20184

Settings

Subject: search.filters.subject.GCM

Search Results

Now showing 1 - 4 of 4
  • No Thumbnail Available
    Item
    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
  • No Thumbnail Available
    Item
    MODELING THE IMPACT OF LAND USE/LAND COVER AND CLIMATE CHANGE ON THE HYDROLOGICAL BEHAVIOR OF ANDASA RIVER CATCHMENT BY USING SWAT
    (Hawassa University, 2017-12-11) NEGUSU TAREKEGN
    Andasa River Catchment is one of the tributary of Abay River located in Upper Blue Nile Basin. In the catchment climate change and land use impacts were not well studied and quantified yet. Hydrological modeling of catchments is essential for future water resource development programs to provide information for decision makers and planners. For hydrological model Simulation SWAT model was used after calibrating and validating the sensitive parameters of the catchment. The calibration, validation and uncertainty estimation were done by SWAT-CUP in particular by SUFI2 project. The model has very good performances to use for the catchment and further, the model is capable to simulate climate change impacts and land use scenarios. Following SWAT model setup, future climate change scenarios were developed for the catchment and their subsequent impact on the water balance were estimated. This study used HadCM3 GCM model from fourth assessment report of the IPCC under A2 (high) and B2 (low) emission scenarios and CanESM2 model from fifth assessment report of the IPCC under RCP4.5 and 8.5 representing the maximum and minimum condition of CO2 emissions. The coarse GCM resolution was down-scaled by Statistical Downscaling Model (SDSM). The model used to downscale the station level weather variables temperature (minimum and maximum) and rain fall called predictand with the coarse GCM predictors by the principle of multiple regression for the future till 2099 /2100. The future downscaled weather variables were divided into 3 periods; 2013-2042, 2043-2072, and 2073-2099. The change in temperature (˚C) and rain fall (%) is calculated for the three periods in comparison to the base period (1993-2012). The climate projection result indicated increasing monthly temperature and decreasing tendency of rain fall under all scenarios. However, all scenarios agreed in increasing temperature and decreasing rain fall trends in the three periods while averaged. The change in temperature (˚C) and rain fall (%) is introduced to SWAT to simulate the water balances. Based on SWAT model simulation significant reduction of stream flow was observed under almost all scenarios in all future periods. Moreover land use scenarios were developed for the base period (1991-2012) and for future period (2013-2042). Best case scenario (afforestation and conservation) were developed for the two periods. Agricultural land expansions considered as worst case scenario. And their respective hydrological simulation indicated that in best case scenario significant increase in infiltration was observed. Hence, it enhances base flow and maintains stable dry season flow in comparison to worst case scenario
  • No Thumbnail Available
    Item
    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 CHAKA
    Climate 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.
  • No Thumbnail Available
    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 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