Hydrologic impacts of climate change on the Nile River Basin: implications of the 2007 IPCC scenarios

Abstract. Understanding responses by changes in land use and land cover (LULC) and climate over the past decades on streamflow in the upper Blue Nile River basin is important for water management and water resource planning in the Nile basin at large. This study assesses the long-term trends of rainfall and streamflow and analyses the responses of steamflow to changes in LULC and climate in the upper Blue Nile River basin. Findings of the Mann–Kendall (MK) test indicate statistically insignificant increasing trends for basin-wide annual, monthly, and long rainy-season rainfall but no trend for the daily, short rainy-season, and dry season rainfall. The Pettitt test did not detect any jump point in basin-wide rainfall series, except for daily time series rainfall. The findings of the MK test for daily, monthly, annual, and seasonal streamflow showed a statistically significant increasing trend. Landsat satellite images for 1973, 1985, 1995, and 2010 were used for LULC change-detection analysis. The LULC change-detection findings indicate increases in cultivated land and decreases in forest coverage prior to 1995, but forest area increases after 1995 with the area of cultivated land that decreased. Statistically, forest coverage changed from 17.4 % to 14.4%, by 12.2 %, and by 15.6 %, while cultivated land changed from 62.9 % to 65.6 %, by 67.5 %, and by 63.9 % from 1973 to 1985, in 1995, and in 2010, respectively. Results of hydrological modelling indicate that mean annual streamflow increased by 16.9 % between the 1970s and 2000s due to the combined effects of LULC and climate change. Findings on the effects of LULC change on only streamflow indicate that surface runoff and base flow are affected and are attributed to the 5.1 % reduction in forest coverage and a 4.6 % increase in cultivated land areas. The effects of climate change only revealed that the increased rainfall intensity and number of extreme rainfall events from 1971 to 2010 significantly affected the surface runoff and base flow. Hydrological impacts by climate change are more significant as compared to the impacts of LULC change for streamflow of the upper Blue Nile River basin.

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On Foes and Flows : Vulnerabilities, Adaptive Capacities and Transboundary Relations in the Nile River Basin in Times of Climate Change

L'Europe en Formation ◽

10.3917/eufor.365.0099 ◽

2012 ◽

Vol 365 (3) ◽

pp. 99 ◽

Cited By ~ 5

Author(s):

P. Michael Link ◽

Franziska Piontek ◽

Jürgen Scheffran ◽

Janpeter Schilling

Keyword(s):

Climate Change ◽

River Basin ◽

Nile River ◽

Nile River Basin

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Analysis of the combined and single effects of LULC and climate change on the streamflow of the Upper Blue Nile River Basin (UBNRB): Using statistical trend tests, remote sensing landcover maps and the SWAT model

10.5194/hess-2017-685-rc2 ◽

2018 ◽

Author(s):

Anonymous

Keyword(s):

Climate Change ◽

Remote Sensing ◽

River Basin ◽

Swat Model ◽

Nile River ◽

Blue Nile ◽

Nile River Basin ◽

Blue Nile River Basin

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

Hydrology and Earth System Sciences ◽

10.5194/hess-15-209-2011 ◽

2011 ◽

Vol 15 (1) ◽

pp. 209-222 ◽

Cited By ~ 121

Author(s):

M. T. Taye ◽

V. Ntegeka ◽

N. P. Ogiramoi ◽

P. Willems

Keyword(s):

Climate Change ◽

River Basin ◽

Nile River ◽

Climate Change Scenarios ◽

Hydrological Models ◽

Lake Tana ◽

Source Regions ◽

Hydrological Extremes ◽

Nile River Basin ◽

The Impact

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.

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