Evaluation of Impact of Climate Change on Water Resource Availability in the Catchments of Blue Nile Basin

Abstract

The purpose of this study was to understand the spatial variability of climate change impact in Blue Nile Basin based on hypothetical climate change scenario and using HBV hydrological model. The assessment was done on selected 10 catchments of the basin. A hypothetical scenario within the range of (-30 to +30) for both precipitation arid PET have been investigated . In terms of hydrological modeling performance, ENs criteria, the 10 catchments gave generally in the range between 0 . 59 and 0.83 and in the validation between 0. 56 and 0. 79, which is fair representation of the catchments. Where as interms of evaluation of water resource change, most of the stations exhibit more than 18% increase in runoff for PET decrease of 30% but Chacha catchment has shown extreme increase of runoff above 48.32 %. On contrary, 30% increase in PET showed slightly reduced percentage of reduction in runoff than the Decreased in PET produced. Meanwhile most of the stations exhibit more than 50% increase in runoff for rainfall increase of 30% but Chacha catchment has shown extreme increase of runoff above 100% . On contrary, 30% reduction in rainfall showed slightly reduced percentage reduction in runoff than the increased rainfall produced. Therefore for both scenarios impact assessment has shown that Chacha is the most sensitive catchment followed by catchments Sechi, Birr, Guder, G/Belese,Teme, Muger;Koga, Neshi, and Little Anger. And from the sensitivity map developed for the whole Basin Jemma, Dabus, Part of Belese, Woleka, Wonbera and Beshilo are a Special and overstress sensitive Sub basins, however; Fincha, Anger and Tana Sub Basins have relaxed water resource change sensitivity. These sensitivity analyses conducted on watersheds and river basins under a variety of scenarios may help policy makers to prioritize measures and /or VI understanding the effects of climate change for planning and, management water resources with in the Blue Nile Basin.