investigation of groundwater balance in tuserkan plain of hmaedan using modflow

recent droughts and indiscriminate use of ground water for agriculture, is the main problems of the especially desert country.water crisis has gripped all of country plains, and due tothe reduction of surface water resources and successive droughts, illegal exploitation of ground water resources is increasing.the knowledge of the water balance plains can be helped in the water resources management.tuyserkan plains is one of the most lowland in the hamedan province with widly agricuctural land that is increasing every year, consequently, the pressure on groundwater resources is creased. the aim of this study is invstigation of water balance in tuyserkan plain in water year 88-87 for optimal management of water resources especially for agricultural uses. for this purpose, iso potential of plains is maping next attempted to identify the input and output in plain and ground water balance was calculated manually. the next step using of determining changes volume in plain, accuracy of water balance caculated was determined. finally, there quiring of inputmap andbasic information is providing on modflow numerical model and gms software was runs.result show that plain ground water balances was negetive and shortage of storage was -12.2 mm3 in 1387-88. manually water balance and water table changes supported reult of model ground water balance.