Interaction of Groundwater and Surface water in the Gash Delta

Background and requirements

The Gash River is a torrential stream originates from the Eritrea/Ethiopian Plateau and ends up in a flat delta within the eastern part of Sudan. The length of the river is about 110 km from the border to the end of the Delta. The flow is seasonal, and occurs between June to October. It varies significantly between the years, from a minimum of 200 to a maximum of 1200 Mm3/year. The river irrigates the large Gash delta, in which the Gash Irrigation Scheme (120,000 feddans) was constructed at the beginning of the 20th century. The Gash is also the main supply of water for the Kassala Town. The Gash Delta is experiencing serious decline of groundwater table due excessive abstraction both for domestic and irrigation water supplies. It is claimed that the Groundwater table has dropped by 4 to 7 m during the last three decades. This has created serious pressure both on quality and quantity of available water resources in the Gash

Research objectives

The main objective of this research is to conduct ground water resources assessment within the Gash Delta, specifically to quantify the seasonal interaction between surface and groundwater resources within the delta. Secondly, to provide guidelines for safe groundwater abstraction at different spatio-temporal scales.

Method

After collecting tographical and hydrological data from the area, the main task would be to develop a detailed groundwater model to simulate water resources system of the Gash Delta. The model could start from the Eritrean/Sudan border and ends up at the Gash Delta around 110 km downstream.River flow data is available at the border station, while  piezoelectric water level measurements are available at a number of monitoring wells. The study should then provide clear guidelines on safe groundwater abstraction at different spatial and temporal scales within the Gash Delta.