ESTIMATION OF GROUNDWATER RECHARGE IN SAFWAN-ZUBAIR AREA, SOUTH OF IRAQ, USING WATER BALANCE AND INVERSE MODELING METHODS

The main objective of this study is to estimate groundwater recharge in SafwanZubair area with total area nearly (1200 km2). This area considered as one of the important agricultural region in Basrah City, south of Iraq. In the recent years the demand of groundwater increased for irrigation and other purposes. As a result of increasing demand for groundwater there is an urgent need for assessing groundwater recharge in this area especially at this time where the country suffers from scarcity of water. Two methods, water balance (WB) and inverse modeling technique used for estimating groundwater recharge. Water balance technique established on the concept balance between in and out water from the aquifer, climate parameters from Barjesiyah meteorological station for the period (2013-2014) are used to estimate groundwater recharge by this method, so the percentage value of recharge about (20.11%) from yearly rainfall. A two dimensional mathematical model is developed to simulate the flow regime of the upper aquifer of Dibdibba formation. According to the calibration process, the hydraulic characteristics of the upper aquifer have been identified. The percentage groundwater recharge is equaled to (18.17%) of yearly rainfall when using inverse modeling technique