Abstract

Yield decrease caused by crop water deficit, especially in low scale farms and established orchards at semi-arid regions, results in a significant decrease in agricultural productivity. In this study an optimal water release of the reservoir based on prioritization in water allocation to the crop sensitive growth periods was linked to a non-linear optimization model in order to enhance the net income in a given cropping pattern. The proposed model by optimal water allocation for each growth stage of the crop reduced the impact of the imposed water stress in the dry season and increased the net income. The LINGO software has been used to evolve the optimal amounts of both water and land for the existing crops. The proposed model was applied for Razmgan area a semi-arid region which is located 10 km south of the Shirvan city, northern Khorasan province, Iran. Various scenarios of the water release from the existing auxiliary reservoir, to remove/reduce the imposed water-stress during the crop growth stages have been explored. Results show in the optimal case, whole of the existing water deficit is removed in months of July, August, September, October and November, only 13% of the deficit remains in month of May and in month of June the amount of deficit decreases to 42.16%. Also the proposed model is efficient and annual net income will increase to 26.21%, moreover, the total water consumption will decrease to 10.71% than the current status.

Key words: Water deficit, agriculture income, sensitive growth stages, cropping pattern, optimal water release.