Determination the suitable economical strategy to conservation of groundwater resources of Qazvin plain

Qazvin plain is one of the country's capable plains to product of agricultural products. During two last decades the level of groundwater decreased in the Qazvin plain and water balance has been negative because of inordinate shafts digging and irregular use of groundwater. To conservation of groundwater resources in this plain need to the strategies and appropriate policy that will apply in this context. Its prerequisite is more recognition of farmer's behavior. Therefore, in present study used of positive mathematical programming and production function with constant elasticity of substitution to investigate farmer's behavior in using of groundwater and determination appropriate strategy to conservation of groundwater resources in Qazvin plain. The investigated strategies were including increase of the water price, decrease of the availability water and deficit irrigation strategy that were investigated under the various scenarios. The required data are registry information and related to year 2011-2012 that by referral to the relevant departments in Qazvin province were collected. The model was solved in the GAMS 23/9 software. The results showed that all the investigated strategies in this study leads to water saving but the average of gross profit changes decreases 3/13, 8/61 and 5/54 percent respectively with increase of the water price, decrease of the availability water and deficit irrigation. Finally, the irrigation water pricing policy was proposed to conservation of groundwater resources of Qazvin plain according to the less reduction in the average of gross profit changes and the deficit irrigation strategy put in the premiership after it.