A water supply-based optimization model for water distribution in two-level canal systems

Abstract

【Objective】 Optimizing water distribution in canal-irrigation districts is a prerequisite to improve irrigation water use efficiency. This paper proposes an optimization method to distribute water in two-level canal-irrigation systems. 【Method】 The method was based on water supply to irrigation districts; it optimizes volume of water distribution, water distribution flow rate and time for each water use unit. We considered two scenarios. The first one was insufficient irrigation where water supply cannot meet water demand during the growing season of crops, in which the model calculated the allocated water for each water user first using water resource allocation coefficient, and then determined the water distribution using the optimal distribution model. The second was sufficient irrigation where water supply meets water demand; we first ranked the priority of the water distribution to each user, and then determined the volume of optimal water flow and timing. The objective of the optimization in both scenarios was to maximize water flow rate and expedite water distribution. The model was applied to the Bojili Irrigation District. 【Result】 The model can optimally allocate and distribute water across the canal system. When water supply is ample, the model can optimally determine water distribution sequence based on the allocation coefficient. When water is scarce, the model can optimally allocate water to each user based on the distribution coefficient. In both scenarios, water distribution flow rate in the main and branched canals exceed 80% and 75% of the maximum flow limits in the first and second scenarios, respectively. The water distribution period for the first and second scenarios is 10.90 and 17.84 days, respectively. 【Conclusion】 The model we developed is effective and provides an improved water allocation method for water management in irrigation districts.

Keywords

• canals water distribution
• water resources allocation
• optimal water allocation
• irrigation districts
• water distribution model