University of Khartoum

Impact of Upstream Interventions on Groundwater in the Blue Nile Basin - Sudan

Impact of Upstream Interventions on Groundwater in the Blue Nile Basin - Sudan

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Title: Impact of Upstream Interventions on Groundwater in the Blue Nile Basin - Sudan
Author: Sidahmed, Mohamed Omer Ibrahim
Abstract: Groundwater it is a key element for human settlement and sustained socio-economic development in the Blue Nile Region. There is ample evidence that the Blue Nile is the main source of recharge to the underlying groundwater basin. Recently, there has been a growing concern about the consequences of upstream water development projects in Ethiopia on the Blue Nile flows and their likely impacts on the interaction between surface flow, and groundwater, and the quantities of aquifer recharge. The main objectives of this study are to investigate such impacts on the interaction between the aquifer and the Blue Nile River and to quantify the likely changes in the groundwater recharge. Hence sound groundwater development and management policies are to be recommended to meet current and future water demands. Based on the geologic and hydrologic characteristics of the study region a groundwater flow model has been developed for the area using the well-known software MODFLOW. The model has been calibrated using limited historic groundwater water level data in 25 wells for 2005, as well as river water level data for the same period. The model was used to estimate the groundwater recharge volumes under existing conditions (before construction of the Grand Ethiopian Renaissance Dam GERD) which was found to be about 1.5 BCM per year. The Blue Nile water levels after the construction of GERD were then investigated along the reach between Rosaries and Khartoum. Such levels were introduced into the model and the groundwater recharge was re-estimated. The results obtained show that the proposed upstream intervention in the Blue Nile Basin (GERD) does not have any significant impact on the annual recharge volume to the Blue Nile groundwater Basin and the general groundwater flow regime. However, the distribution of recharge during the year has changed according to the modified Blue Nile water levels. Various groundwater development scenarios have been investigated using the developed model. The results show that groundwater abstraction can be increased by 50% above the current level without serious groundwater level decline. Beyond this limit, however, increase in groundwater abstractions will not be fully balanced by recharge from the river resulting in a reduction of the groundwater storage and decline of the groundwater levels.
Description: 151page
URI: http://khartoumspace.uofk.edu/handle/123456789/17403
Date: 2015-12-02


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