IMPACT OF CLIMATE CHANGE ON SURFACE WATER AVAILABILITY IN THE MOJO RIVER CATCHMENT

Abstract

Climate change is likely to have severe effects on water availability in Ethiopia. The aim of the present study was to assess the impact of climate change in the Modjo River, Upper Awash Basin. The Statistical Downscaling Tool (SDSM) was used to downscale the HadCM3 (Hadley centre Climate Model 3) Global Circulation Model (GCM) scenario data into finer scale resolution. The Soil and Water Assessment Tool (SWAT) was set up, calibrated and validated. SDSM downscaled climate outputs were used as an input to the SWAT model. The climate projection analysis was done by dividing the period 2011-2099 into three time windows with each 30 years of data. The period 1980-2010 was taken as the baseline period against which comparison was made. Results showed that flow volume may decrease in the 90-year period (2020, 2050 and 2080) this decrease may. in seasons .Kiremit(2020,2050 and 2080) -94.36%,- 43.38% and -49.31% in A2a respectively and -97.21% (2020) and -97.51% (2080) and negligible in 2050 for B2a scenario and Belg seasons should a decrease and is -92.12% and - 80.035 in 2020 for A2a and B2a scenario respectively. In 2050 it should an increase is+3.87% for A2a and negligible for B2a and for 2080 it is -55.54% and -64.94% for A2a and B2a respectively that expected to show the larger share in decreased flow volume for both scenario and in Bega season may a decrease in 2080 for A2a by -54.46% , in B2a may decrease by - 67.33% in 2020 and negligible for 2080s while for A2a in 2020 and 2050 it may increase by +43.29% and +13.995 respectively when one observe annual flow for both scenarios (2020,2050 2080) it may decrease by-47.73,-8.51% and-53.10 %respectively in A2a scenario and - 81.52%,thechange negligible and -30.33% respectively in B2a scenario. Overall, it appears that climate change will result in an annual decrease in flow volume, ranges for A2a -8.51%-to - 47.73% and from -30.33% to-81.52% for B2a scenarios