Assessment of Climate Change Impact on Flood Frequency of Bilate River Basin, Ethiopia

Abstract

Climate change have different impacts on many sectors among those impacts of climate change on water resources, especially on flood frequency of Bilate Watershed were discussed. The study was conducted to asses climate change impact on flood frequency of Bilate River basin. The input data such as (DEM-90m), soil, land use, meteorological data (precipitation, maximum and minimum temperature, wind speed, sunshine), Hydrological data (stream flow) were obtained from ministry of Water resource, irrigation and energy and national meteorology agency respectively. The obtained data was analyzed by using data analysis technique and the climate data was bias corrected for both temperature and precipitation using power transformation technique and linear regression method respectively and finally preferred as in put for HEC-HMS model to calibrate the stream flow data from the year 1988 to 2003 and validate from 2004 to 2010. The R² and Nash- Sutcliffe Efficiency (NSE) value for the Watershed were 0.75 and 0.611 for calibration and 0.78 and 0.623 for the validation respectively. Once the calibration was completed HEC-SSP software was used to done flood frequency analysis of the watershed using different type of distributions. The analysis was shows that among different type of distributions log normal and Pearson type (III) distributions are good and that are used to observe the climate change impact on flood frequency of Bilate River basin.

Keywords: Climate Change, HEC-HMS Model, RCP data HEC-SSP Software, Bilate River Basin.