The increase in groundwater extractions combined with prolonged dry periods has been accompanied by decline in water table in the western part of Iran. These have lead to negative ground water balance. Preliminary unit hydrograph studies of many basins shows severe depletion of groundwater table occurred in recent years. Some available groundwater models were evaluated and among them, the mathematical model (Modflow), were used to develop a management tool to support water planning and evaluate groundwater artificial recharge . The modifying model domain, the initial basic structure for the model was made, by using necessary data such as number of different type of layers, depth to top and bottom layers and water table elevation in observation wells. Calibration of model was attempted considering the groundwater table elevation of selected years, as a initial hydraulic head and pizometeric data in that year with optimization of some parameters such as horizontal hydraulic conductivity, specific yield and hydraulic conductance of riverbed and etc. Accordingly, suitable site to implement artificial recharge were selected to be simulated. Artificial recharge effects assessed in modeled area. The selected areas in this program are namely as Mahidasht and Bahar plains which are located in the western part of Iran and are considered to be Semi-Arid Areas. In Mahidasht plain, it was found that if flow of 0.3 m3/s is introduced to an area of 10.5 hectare, with considering infiltration rate at acceptable rate, the volume equivalent to 25000 m3 can be estimated to be recharged in to subsurface layers. The result shows that, the volume of recharged water in to subsurface layers by artificial recharging structure in the five months of wet period will be equivalent to 3750000 m3. With implication of the recharge, the water table in the model domain area has been increased to about 6m for a year, and the effect of radial flow was found to be four kilometers
