Application of GIS to estimate ground water budget in Talesh plain

To optimize the use of water resources, the amount of available surface and underground water must be known. The optimization process affects the environment and may damage water stores, if it was not done with due consideration. Currently, many of Iranian plains are prohibited from ground water use, and some of the lands have already been damaged.To determine water resources scientifically, current water budget must be known. Statistical, hydrological, and hydro geological information must be gathered, and analyzed to determine the water budget. Underground water budget is used more frequently in Iran, as such, in this paper, hydrological budget has been computed, and then, underground water budget has been calculated and delivered in Geographic Information System (GIS) environment. The results have then been presented in a hard copy map. Using water budget information, critical points have been estimated, such that the damage to the underground aquifer is minimized. Permissible water extraction area, and the suitable well distances are also depicted. According to the results of this research, most of Talesh plain can be used for water revenue.