A coupled water allocation simulation–optimization model to advance agricultural water management

Proper water allocation plays a key role in sustainable water resources management due to limited water resources and increasing demand for agricultural water consumption. Although the soil water balance approach is widely used to determine agricultural water allocation, simultaneous application of this approach and optimization of agricultural water allocation has received little attention. To bridge this knowledge gap, a coupled irrigation simulation model (ISM) with genetic algorithm (GA) optimization model is developed not only to obtain optimal agricultural water allocation, but also to determine a practically optimal irrigation scheduling (i.e., irrigation duration and irrigation interval). First, an irrigation simulation model (ISM) is developed based on soil water balance approach. Then, GA optimization model is employed to couple with the ISM for optimization of the irrigation scheduling. The coupled ISM-GA optimization model strives to decrease both water shortage and surplus water through the optimization of the water allocation to irrigation demand. The developed framework is applied to optimize agricultural water allocation and irrigation scheduling of three different agricultural zones supplied by Al-Aswad falaj, a traditional water supply system located at the capital of Oman, Muscat. The results disclose that the proposed ISM-GA optimization model decreases the amount of water shortage of the current irrigation water allocation by 32, 20, and 10% for the three agricultural zones, respectively. These results indicate that the developed framework is efficient to determine a practically optimal irrigation scheduling for several agricultural zones under multicrop and intercropped systems.