More research neededDams and groundwater discharge [Archives:2004/709/Local News]

February 5 2004

By Ayoub Ahmad Almhab
For The Yemen Times
[email protected]

Many water basins in Yemen face water shortages due to climatic changes and overuse of groundwater. There is need to develop and properly manage available water resources to assure their sustainability.
At present, considerable investments were allocated for constructing and rehabilitating water storage structures, to enhance ground water discharge, expand irrigated areas, and provide water for other uses.
To understand the effect of dams on water status in given water basin, various investigations are required for determining surface water and groundwater hydrology, and subsequently advising proper water resource management strategies, such as dam construction and water conservation techniques.
In this study Sawan watershed, which is located in Sana'a basin, was selected to study the effect of three small dams on shallow groundwater discharge.
To study the effect of dams on groundwater discharge, static water levels in a number of open wells was observed in 2000 and 2001.
Static water level (SWL) of wells near Mukhtan, Konazer, Beryan dams were significantly affected by the distance from the dams. The SWL of wells closer to Mukhtan dam was 9 m while SWL of well at distances of about 5.7 Km from the dam was 22.6 m.
In the case of Beryan dam, SWL were 7.9 m and 11.7m for wells at distances 0.3 km and 6.1 km from the dam, respectively, while SWL was found at 9 m in wells near Konazer dam and 22.3m in wells at 4.5 Km from the dam. This indicates the presence of groundwater discharge, especially in the areas near the dams.
This study recommends documenting hydroclimatic data in order to establish an information database for major watersheds, and to carry out comprehensive studies and investigations on the effects of dams.
An emphasis is required to utilize mathematical models, GIS and other programs in the Rapid Risk Assessment program of watershed and dams.