Assessment of the Economic and Hydrological Effects of the Climate Change in Kharrood Watershed

In the present study first the behavioral patterns of precipitation climatic variable in period 1985-2014 in Kharrood watershed was investigated. Then, to analysis effects of climate change resulting from reduced rainfall under different scenarios mild, moderate and severe on hydrological (available water resources and economic value of irrigation water) and economic (agricultural products and farmers’ gross profit) variables from a biophysical- economic modeling system was used. Above modeling system includes the products yield function based on rainfall (biophysical part of model) and positive mathematical programming approach (economic part of model) that was solved in consecutive three stages and in the GAMS 24.1 software. The required data by the rain gauge stations and the relevant agencies in Qazvin province were collected. Behavioral pattern of precipitation showed that this climate variable was reduced in Kharrood watershed after year 2001. The results of proposed model showed that climate change resulting from reduced rainfall under mild to severe scenarios decreases the available water resources 11/3 to 23/0 %, increases the economic value of irrigation water 7/08 to 15/22 %, decreases the total acreage of water crops 5/14 to 16/39 % and decreases the farmers’ gross profit 6/58 to 13/41 % compared to the base year. The highest decrease of the available water resources in Kharrod watershed under severe scenarios and at a rate of 15/29 million cubic meters was obtained. Finally, use of deficit irrigation techniques, determination the rate of water charge to farmers on the basis of equality consideration, fallow-lands and providing financing convenience to farmers for farms outfit to new irrigation system to contrast with the effects of climate change and protection of water resources in this watershed were proposed.