The impacts of different land use changes on groundwater level using quantitative model WEAP (Case study: Chaharmahal Bakhtiari province, Iran)

     Reduction of water resources limits the ability of farmers for food production and subsistence. Nowadays the quick growth of population has been the most important factor in the decline of renewable water. In many parts of Iran, including region of interest, the major factor in water resources decline was land use change, that may  cause to ecological destruction and disruption. Sustainable development can be achieved with proper management of watersheds. This study tried to determine the effect of land use type on water resources the ChaharmahalBakhtiari plains. TM images in May of 1982, 2000 and 2012 were used to prepare the land use maps for 8 plains. The resulted maps for 2012 were reviewed using topographical maps (1:25000) and field observations. The water level measurements during 2002 to 2012 in different plains were used for calibration and validation of WEAP model. The quantitative model used to determine the effects of land use changes on groundwater level. The extent of Agricultural land use have increased from 1982 to 2002 and 2012 from 28.8% to 35.6% and 38.7% accordingly. The results revealed that except of Farsan, Shalamzar and Gandoman the other plains have negative groundwater balance. The model simulation showed that continuing the current harvesting cause to critical situation in the near future. To compensate the negative water balance of Shahreh Kord, Borojen, Sefid dasht, Kiyar, Flared and Khan mirza, it would be necessary to reduce the consumption of groundwater resources of these plains up to %48, %32, %66, %30, %13 and %12, respectively. The change of land use from grasslands to agriculture was the main reason of reduced the groundwater reserves.