Calculation framework for agricultural irrigation water consumption in multi-source irrigation systems

This study proposed a calculation framework to reasonably and effectively calculate the agricultural irrigation water consumption (AIWC) and reused irrigation return flow (IRFr) in multi-source irrigation systems based on the modified Soil and Water Assessment Tool (SWAT). The calculation framework was applied in the Yangshudang (YSD) watershed in southern China over the years. Results showed that total AIWC and IRFr of the irrigation system increased as the degree of drought increased. The improved total AIWC (AIWCnew,g), which considered the reuse of return flow, is less than the traditional total AIWC (AIWCo,g). In addition to the backbone water source of the Zhanghe Reservoir, 44.54% of the AIWCo,g of the YSD watershed came from ponds inside the YSD watershed under multiyear average conditions. The IRFr accounted for 6.49% of the AIWCo,g, and the AIWCnew,g accounted for 93.51% of the AIWCo,g. For accuracy and management, this calculation framework and improved AIWC are suggested to be used in the multi-source irrigation systems. •Improved agricultural irrigation water consumption considering the reuse of return flow was defined in irrigation systems.•A calculation framework for improved agricultural irrigation water consumption was proposed.•The water supply ratios of different water sources in a multi-source irrigation system were analyzed.•A quantitative relationship between traditional and improved agricultural irrigation water consumption was revealed.