Economic evaluation of optimum cultivating pattern for reducing the use of groundwater in Dehgolan plain

In recent years, the Dehgolan plain has been faced by a sharp drop in groundwater and land subsidence due to the drought and over-harvesting of water resources. Hence, one of the most important water management practices is management of cultivating pattern that has more importance in drought situations in order to reduce water super-crisis. This plain with an area of 62.4 thousand hectares and the coordinates of 10' 470 to 44' 480 eastern longitudes and 00' 350 to 32' 350 northern Latitudes is at the eastern of Kurdistan province. This research was designed to develop an optimal cropping pattern (wheat, barley, alfalfa, onion, potato, clover and sainfoin) for under low water conditions. Moreover, this paper presented an optimal irrigation program for maximizing the gross profit of the farm. For this purpose, data from the crop years of 2016-2017 was used as input of Positive Mathematical Programming Model. The results showed that in the optimum conditions for plant production, the amount of water saving in the first to third scenario was 22.1%, 30.5%, and 35.5%. On the other hand, the gross profit of the farm decreased 4.6%, 9.3% and 14.8% respectively. Consequently, it can be said that applying irrigation policy in stages of growth of products that are less susceptible to dehydration results in farmers to select a cultivation pattern that has high economic benefits compared to cultivating other product.