Climate Change Impact on Statistical Downscaling of Daily Rainfall Data from Global Circulation Models in Chiro and Hurso Stations of Eastern Ethiopia

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Climate Change, Climate Change Prediction, GCMs, Statistical Downscaling
At this time generation of global and regional climate models are restricted in their usefulness for many sub-grid scale applications, including hydrology and water resources, due to their coarse spatial resolution. Downscaling attempts to resolve the scale discrepancy between climate change scenarios and the resolution required for hydrological and other impact assessment. General Circulation Models (GCMs) which are considered as the most advance tools for estimating future climate change scenarios operate on coarse resolutions. Downscaling of GCM output is used to assess the impact of climate change on local water management activities. The Objectives of the study was: To develop climate change scenarios for (rainfall). The study was carried out in eastern Ethiopia specifically at Chiro and Hurso meteorological stations. Chiro is Located in West Hararghe Zone in eastern Ethiopia. It has 9 Â °07N latitude, 40 Â °86E longitude and an altitude of 1815 meters above sea level and Hurso is Located in the Shinile Zone of the Somali Region, in eastern Ethiopia, it has 9 Â °96N latitude, 41 Â °67E longitude and an altitude of 1110 meters above sea level. The study area situated for three future climate periods of 30 years from 2011 until 2099. The outputs of HadCM3 coupled atmosphere-ocean GCM model for the A2 and B2 emission scenarios were used to produce the future scenarios. These outputs were downscaled to the study area scale through the application of the SDSM model. The study found that there is an overall trend significant variation of monthly and seasonal precipitation from the base period level. Results of the study include scenario generation for the base periods and for the future times; the generated future values indicate an increasing trend for B2a emission scenario and decreasing trend for A2a emission scenario at Chiro station. At Hurso station the generated future scenarios generally showed an increasing trend with respect to the base period for two emission scenarios (A2a and B2a) for 100 years. The mean annual rainfall indicates an increase by 167.11% and 138.56% in 2050s and 2080s respectively and decreases by 35.43% in 2020s for A2a scenario, similarly for B2a scenario indicates an increasing trend by 90.14%, 31.89% and 78.98% in 2020s, 2050s and 2080s from the baseline period respectively at Chiro station. The mean annual rainfall indicates a decrease by 6.52%, 11.72% and 32.14% in 2020s, in 2050s and 2080s respectively from the base period in A2a scenario and in the B2a scenario the annual rainfall indicates a decrease of rainfall by 10.61%, 13.87% and 14.89% in 2020s, 2050s and 2080s respectively from the base period at Hurso. In general the investigations for both stations tell as how changes in rainfall may affect on different hydrological components by using downscaled out-puts climate models for the future time. Therefore, it is necessary to incorporate climate change scenarios for strategies planning in soil and water conservation techniques, Water harvesting technologies and for any sustainable strategies