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Impacts of Climate and Land Use Change on Hydrological Response in Gumara Watershed, Ethiopia
  • +2
  • Achenafi Gebresilassie,
  • Yihun Dile Taddele,
  • Dereje Hailu,
  • Haimanote Bayabil,
  • Kibruyesfa Sisay
Achenafi Gebresilassie
Addis Ababa University
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Yihun Dile Taddele
Texas A&M University System
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Dereje Hailu
Addis Ababa University
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Haimanote Bayabil
University of Florida
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Kibruyesfa Sisay
United Nations Development Programme Ethiopia
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Abstract

Climate and land-use change affect the hydrologic cycle by altering streamflow (SF), surface runoff (SR), base-flow (BF), and evapotranspiration (ET). The Lake Tana basin has experienced both land-use and climate change over the past 40 years, and this change can continue in the future. Several studies have addressed the separate impacts of either land-use or climate change on the watershed’s hydrology, but few have explored the combined impacts. In this study, the SWAT model was applied to evaluate the combined impacts of land-use and climate change on hydrological responses in Gumara watershed. This study examined four land-use scenarios that include the present (2015) and projected (2050) land-use based on the business-as-usual trend (BAU), expansion of irrigation crop (EIC), and expansion of forestland (EFL). The climate variables were simulated using Weather Research and Forecasting (WRF) model for the baseline (2005-2015) and projected period (2045-2055) under RCP4.5 and RCP8.5 scenarios. The result showed that SR increase by 5.1% under BAU scenario while BF decrease by 6.5% without altering SF and ET noticeably. On the contrary, SF decrease by 12.5% and 5.2% respectively under EIC and EFL scenarios, while ET increase by 4.8% and 8.9% respectively under EIC and EFL scenarios. The simulated SF, SR, and ET under RCP8.5 may increase significantly by 34.3%, 51.8%, and 12.2%, respectively. Similarly, the simulated SF, SR and ET may increase significantly under the combination of all three land-use and RCP8.5 scenarios. The findings suggested that climate change will have a greater effect on hydrologic responses than land-use change. The expansion of agriculture and the wetter climate would exacerbate flooding, while the expansion of irrigation and forest offset SF increases. The results of this study can be useful to decision-makers and planners in the design of adaptive measures to climate and land-use change.