Comprehensive Biophysical-Economic Modeling of Climate and Agriculture (Case Study: Roodshour Watershed)

In this study using panel dataset (combining the time series data related to the climatic variables of rainfall during 1986-2016 and the cross sectional data related to the base year 2015-2016) the comprehensive biophysical-economic modeling of climate and agriculture in Roodshour watershed basin was studied. In order to achieve the applied results, modeling is done by combining two parts of the biophysical (the products yield estimation model) and the economic (positive mathematical programming model) under mild, moderate and severe testing scenarios and with advanced programming in the GAMS 24.7 software environment. The results show that after year 2001, behavioral pattern of rainfall climate variable was accompanied with a decreasing trend in the Roodeshoor basin. With occurrence of the climate change resulting from rainfall reduction under mild, medium and intense scenarios, the available water resources decreased 5/75 to 13/8 percent, agricultural products decreased 3/60 to 8/54 percent and farmers' gross profit decreased 2/71 to 8/04 percent. But the economic value of irrigation water increases 5/13 to 12/7 percent ratio to base year. Finally, in order to protection of the water resources in the Roodeshoor basin and coping with the effects of climate change, Redetermination of the rate of water charge to farmers on the basis of equality consideration, fallow-lands and equipping farms to modern irrigation systems were proposed.