Climate Change Impacts on Water Resources in the Upper Blue Nile River Basin, Ethiopia¹

Abstract

Kim, Ungtae and Jagath J. Kaluarachchi, 2009. Climate Change Impacts on Water Resources in the Upper Blue Nile River Basin, Ethiopia. Journal of the American Water Resources Association (JAWRA) 45(6):1361‐1378. Abstract: Climate change affects water resources availability of international river basins that are vulnerable to runoff variability of upstream countries especially with increasing water demands. The upper Blue Nile River Basin is a good example because its downstream countries, Sudan and Egypt, depend solely on Nile waters for their economic development. In this study, the impacts of climate change on both hydrology and water resources operations were analyzed using the outcomes of six different general circulation models (GCMs) for the 2050s. The outcomes of these six GCMs were weighted to provide average future changes. Hydrologic sensitivity, flow statistics, a drought index, and water resources assessment indices (reliability, resiliency, and vulnerability) were used as quantitative indicators. The changes in outflows from the two proposed dams (Karadobi and Border) to downstream countries were also assessed. Given the uncertainty of different GCMs, the simulation results of the weighted scenario suggested mild increases in hydrologic variables (precipitation, temperature, potential evapotranspiration, and runoff) across the study area. The weighted scenario also showed that low‐flow statistics and the reliability of streamflows are increased and severe drought events are decreased mainly due to increased precipitation. Joint dam operation performed better than single dam operation in terms of both hydropower generation and mean annual storage without affecting the runoff volume to downstream countries, but enhancing flow characteristics and the robustness of streamflows. This study provides useful information to decision makers for the planning and management of future water resources of the study area and downstream countries.

Optimal Operation of Hydropower Reservoirs under Climate Change: The Case of Tekeze Reservoir, Eastern Nile

“…Climate change studies showed temperature increased and precipitation pattern changed throughout arid and semi-arid regions of Africa [30][31][32] and affected the hydrological processes that impacts reservoir operation. Most studies showed the impacts of climate change on African hydropower reservoirs [23,[33][34][35][36]. Kim and Kaluarachchi [33] and Beyene et al [34] projected that precipitation and temperature will be increased in the Nile River basin and have positive effect on hydropower production, but Yamba et al [35] and Hamududu and Killingtveit [36] investigated that in the next 60 years hydropower production show a gradual reduction with large variability in the Zambezi River basin.…”

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

“…Further, previous studies show that many parts of the Nile basin are sensitive to climatic variations (Conway and Hulme, 1996;Strzepek 1996, 1998a, b;Conway, 2005;Kim et al, 2008;Beyene et al, 2010) implying that climate change will have a considerable impact on the resource. Therefore, it is necessary to analyse the possible changes in the different water resources aspects under the changing climatic conditions.…”

“…Potential impact of climate change in the Nile basin has been studied using outputs from General Circulation Models (GCMs) by different researchers on different catchments of the basin during the previous years (Conway andHulme, 1993, 1996;Strzepek and Yates, 1996;Conway 2005;Kim et al, 2008;Beyene et al, 2010;Elshamy et al, 2009a, b;Elshamy and Wheater, 2009;Soliman, et al, 2008;Githui et al, 2009). The studies used different methods for translating specified changes in climatic inputs into changes in hydrological regimes.…”

“…Afterwards, hydrological models were used to generate the hydrological regimes. For example, Elshamy et al (2009a) used bias corrected statistical downscaling method to analyze outputs of 17 GCMs and to construct downscaled scenarios while Kim et al (2008) applied the change factor method using monthly totals to construct the future climate variables. Beyene et al (2010), states that most of the previous studies were limited by the coarse spatial resolution of the GCMs used and the small number of GCMs that could be evaluated.…”

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

“…Recently, [2] [3] studied climate change impact in Upper Blue Nile by direct use of GCM outputs ignoring aspects of the course scale resolution. 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.…”