Assessment of climate change impact on hydrological extremes in two source regions of the Nile River Basin

Abstract

Abstract. The potential impact of climate change was investigated on the hydrological extremes of Nyando River and Lake Tana catchments, which are located in two source regions of the Nile River basin. Climate change scenarios were developed for rainfall and potential evapotranspiration (ETo), considering 17 General Circulation Model (GCM) simulations to better understand the range of possible future change. They were constructed by transferring the extracted climate change signals to the observed series using a frequency perturbation downscaling approach, which accounts for the changes in rainfall extremes. Projected changes under two future SRES emission scenarios A1B and B1 for the 2050s were considered. Two conceptual hydrological models were calibrated and used for the impact assessment. Their difference in simulating the flows under future climate scenarios was also investigated.The results reveal increasing mean runoff and extreme peak flows for Nyando catchment for the 2050s while unclear trend is observed for Lake Tana catchment for mean volumes and high/low flows. The hydrological models for Lake Tana catchment, however, performed better in simulating the hydrological regimes than for Nyando, which obviously also induces a difference in the reliability of the extreme future projections for both catchments. The unclear impact result for Lake Tana catchment implies that the GCM uncertainty is more important for explaining the unclear trend than the hydrological models uncertainty. Nevertheless, to have a better understanding of future impact, hydrological models need to be verified for their credibility of simulating extreme flows.

Impacts of climate change under CMIP5 RCP scenarios on the streamflow in the Dinder River and ecosystem habitats in Dinder National Park, Sudan

“…The land use map (1 km) in this study was obtained from the Land Cover Institute (LCI) (http://landcover.usgs.gov/). Daily meteorological data such as temperature and precipitation were collected from the Ministry of Water Resources and Electricity and other different sources for the period (Beyene et al, 2010;Taye et al, 2011;Enyew et al, 2014;Gebre et al, 2015). The MIROC-ESM and CCSM4 (Jury, 2015) models similarly have been selected (Elshamy et al, 2009;Beyene et al, 2010;Setegn et al, 2011).…”

“…The climate change in the Upper Blue Nile basin has been addressed by many previous studies using different climate models and techniques (Elshamy et al, 2009;Beyene et al, 2010;Taye et al, 2011;Setegn et al, 2011;Enyew et al, 2014;Gebre et al, 2015). The Dinder River (DR) is one of the largest tributaries of the Blue Nile River and a major water resource in the Dinder National Park (DNP).…”

Analysis of hydrological extremes at different hydro-climatic regimes under present and future conditions

“…However, it is apparent that the changes in hydrological extremes, i.e. floods and droughts, would have more profound and immediate impacts on agriculture, economy, and human health than the seasonal or monthly changes (Arnell 2011;Taye et al 2011). Changes in hydrological extremes are expected to vary between basins.…”

Hydrological Impact Assessment of Climate Change on Lake Tana’s Water Balance, Ethiopia

“…It is described that hydrological impacts of climate change on the Lake Tana water balance are not well explored [2] [3]. Recently, by applying a perturbation downscaling approach of GCM outputs, [4] investigated the impact of climate change on high rainfall and flow extremes for the Nyando River and Lake Tana catchments in the Upper Blue Nile basin, Ethiopia. The result of their study indicated increases in temperature but did not indicate systematic increases or decreases of rainfall besides changes in inter-annual variability.…”