Optimization Cropping Patterns in Agriculture Wells with Monthly and yearly Water Volume restrictions (case study: Qazvin plain)

Volumetric water delivery is one of the main components of the groundwater balancing plan. In the volumetric water delivery condition, the increase in farmers' income and the optimum use of water should be considered at the same time. The aim of this study was to determine optimum cropping patterns in agriculture wells under volumetric water allocation constraints in the Qazvin plain. In this research, 9 agriculture farms were studied and linear programming was used in the optimization process. The average water productivity in the formal cropping pattern (FCP), optimum cropping pattern with monthly water allocation (OCPM), and optimum cropping pattern with yearly water allocation (OCPY) was estimated at 5283, 9080, and 10570 Rials per cubic meter, respectively. The average productivity in the OCPM and OCPY has increased by 72% and 100%, respectively, compared to the FCP. Also, the average net benefits in the FCP, OCPM, and OCPY were estimated at 52978, 48275, and 88844 thousand Rials per hectare, respectively. The average net benefit in the OCPM has declined by 8.9%, and the average net benefit in the OCPY has increased by 67.7% compared to the FCP that mentioned in water licenses. The average water use in the FCP, OCPM, and OCPY was estimated at 10287, 5150, and 8501 cubic meters in ha, respectively. The average of water use in OCPM and OCPY has declined by 49.9% and 17.4% respectively. The results showed that the formal crop pattern that is mentioned in water licenses of agricultural wells requires a considerable revision and does not conform to volumetric water delivery (allocation) conditions.