ملخص
Sarir basin was a target for development since the early 1970's. The surface area of the Sarir basin is about 350,000 km2. The aquifer thickness reaches up to 1000 m. Water resources in Sarir Basin were planned for development in three different groundwater projects; Sarir North and South agricultural Projects and Sarir West Wellfield for water transportation scheme to the coastal region. The Sarir groundwater system consists of two main aquifers, shallow and deep aquifer, separated by silty clay, siltstone and thin layers of clay. The thickness of the confining layer is approximately 30 to 100 meters. The deep aquifer is multi-layered and consists of unconsolidated and semi-consolidated sediments. The groundwater drawdown resulted from the wellfields abstraction that was monitored through a network of piezometers from 1975 until the end of 2012 is used in this study. Maximum drawdown of 10 m and 6 m were measured in the deep and the shallow aquifers respectively. Because of intermittent pumping records in the Sarir agricultural projects for the last ten years, crop consumptive use values were applied in order to fill the missing data. A total recorded as well as the estimated extracted water of 6.508 bm3 was determined. Drawdown contour maps for five different periods were utilized to calculate the dewatered parts of the two aquifers using double integration method, and then the extracted volumes of water were calculated (6.509 bm3) by adjusting the field measured aquifers storativities. This study shows that reliable interpolated drawdown contour maps can be used to calculate total extracted groundwater when pumping data are limited.