Ground Water Availability and Conjunctive Use Assessment

Despite availability of various water resource studies of the Eastern Nile countries, there has not been a compiled regional groundwater report. The current work attempts to contribute in filling the gap by compiling existing groundwater data and information of Ethiopia. Most of previous studies have indicated that in the Eastern Nile basin countries, the use of groundwater is limited to domestic consumption and micro irrigation development. With regard to irrigation, usually the preference has been for development of surface water. However, with increasing pressure from population growth and climate change, conditions have forced to consider conjunctive use of surface and groundwater resources.

South Sudan extends from latitude 3o 30” N to approximately latitude 12o 15” N and from longitude 23o 30” E to longitude 36o E. It has an area of more than 644,330 km² with population of 11.3 million in 2013, which is predominantly rural. Nevertheless, the country is experiencing a high rate of urban growth. The system of government is decentralised, comprising of national and state levels; in addition to county, payam and boma as local levels. It is rich in biodiversity, which includes swamplands; lush savannas; woodlands; rainforests; and special areas of mountainous vegetation that are home to many species of wildlife and that support a large number of livestock. Most of the inhabitants depend on farming, animal husbandry, fishing and the other natural harvests, catches and products for their livelihoods. Most of the government’s revenue is driven from petroleum sector; and very little is raised from nonoil revenues.

Sudan is endowed with considerable groundwater resources with more than 50% of the surface area of the country underlain by groundwater. This estimate also applies to the areas of Sudan within the Eastern Nile Basin which is the study area of this report. The aquifers of Sudan and those within the study area can be classified into four categories according the dominant aquifer formation. These are: X The Nubian Sandstone Aquifers X The Umm Ruwaba Formation Aquifers X The Recent Alluvial Wadi-fill Aquifers X The Basement Complex Aquifers The Nubian Sandstone Aquifers are the most prevalent in the study area as they cover about 33% of its surface area, while the Umm Ruwaba formation cover about 13%. Alluvial aquifers occur within the deposits of the natural drainage systems. They comprise shallow aquifers of good quality water. These aquifers are significant in areas underlain by basement rocks as they provide a reliable source of water for the communities around them. This study focuses on the large sedimentary aquifers in the Eastern Nile basin within Sudan and will not address the numerous alluvial aquifers in the study area.