Economic Analysis of the Effects of Climate Change on Available Water Resources and Agricultural Products in the Watersheds of Shahrood

In the present study first the behavioral patterns of precipitation climatic variable were investigated during years 1985-2013 in the watersheds of Shahrood. Then, a biophysical- economic modeling system was used to analyse the effects of climate change resulting from reduced rainfall on available water resources, agricultural products and economic indicators of gross profit and water value under different scenarios (mild, medium, and intense climate change). The 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 software. The behavioral pattern of precipitation showed that this climate variable was reduced in the watersheds of Shahrood after year 2006. The results of proposed model also showed that with occurrence the climate change resulting from reduced rainfall the available water resources, total acreage of water crops and farmer's gross profit decrease and economic value of irrigation water increase in watersheds of Shahrood. The highest reduction in available water resources was the amount of 30.03 million cubic meters that was achieved under intense climate change scenario. Finally, utilizing deficit irrigation techniques, determination the rate of water charge to farmers on the basis of equality consideration, providing financing convenience to farmers for farms outfit to new irrigation system and fallow-lands was proposed to contrast with the effects of climate change resulting from reduced rainfall and protection of water resources in the region.