International Symposium on
Drylands Ecology and Human Security
Assessment of Groundwater Resources in Taiz Area, Yemen
Ahmed A. Abdulqader
Geology Department, Taiz University, Yemen
Assessment of ground water resources is particularly important in the regions with large demands for ground water supplies, which also play a key to economic development. In Taiz area, the average urban domestic water consumption is about 30 litters per day per person and people are facing serious water shortage and environment deterioration. The surface and ground water have become undrinkable and is no longer fit for use in agriculture.
The objective of this study is quantitative and qualitative assessment of groundwater resources based on Hydrogeological and hydrochemical investigations. Analysis of pumping test data indicate that the transmissivity of the alluvial aquifer varies from 88 to 1489 m2/day as compared to that of fracture volcanic varying from 4 to 105 m2/day, while the transmissivity of the sandstone aquifer varied from 4 to 247 m2/day. The well yields varied widely in aquifer depending on the grain size, fracture intensity and volcanic intrusions.
Water balance estimations have revealed that the total storage of exploitable groundwater within the study area is about 1029 Mm3. The total annual recharge is estimated at about 41.8 Mm3 while the total annual discharge is estimated at about 58.3 Mm3 which leads to a deficit or an imbalance between the recharge and discharge of about 16.5 Mm3/year.
Field measurements and laboratory analysis of about 50 water samples from the study area indicated that the ion concentrations are high and tend to increase with increasing distance from the recharging areas. The spatial variations in the contaminant concentrations reflected variations due to natural causes and human activities. In general, groundwater in recharging areas is of good quality and suitable for drinking and irrigation. However, high salinity or contaminated water (unsuitable for drinking or irrigation) is found in the shallow aquifers in Taiz plain below the depositional sites and along the main water stream of W. Rasyan.