Irrigation water use and efficiency assessment coupling crop cultivation, commutation and consumption processes

Water use and efficiency assessment from crop production-consumption process provided a new perspective for regional agricultural water management. An evaluation framework of water use efficiency (WUE) coupling crop cultivation, commutation and consumption processes was established in this paper. The impact of virtual water flow on provincial irrigation water use efficiency, and its implications for irrigation management were assessed based on the inter-provincial virtual irrigation water flow (VIWF) estimation for cereals of China The results showed that national IWU, IWP and IE for cereal production in 2018 were 268.89 Gm(3) , 1.815 m(3)/kg and 0.494 respectively. Total VIWF among 31 provinces was calculated to be 85.25 Gm(3) , with the contributions of 43.8% rice, 40.0% wheat, and 16.2% maize. IWP and IE from the crop consumption perspective in all provinces were different from that observed from production perspective, and the effect of crop supply-demand mismatch on irrigation WUE was comprehensive. Virtual water flow was conducive to water resource conservation and irrigation WUE improvement when judged by IWP. However, the result was just the opposite when IE was used as the evaluation. Improving IWP in the North China Plain and Southeast and optimizing trade structure in Northeast and Southwest contribute to national irrigation water conservation from both of the production and consumption perspectives. The evaluation framework proposed in current paper can inspire the research on agricultural water assessment, management and regulation combining the physical and virtual water.

Automated summary

This study establishes an evaluation framework of water use efficiency (WUE) coupling crop cultivation, commutation and consumption processes, and assesses the impact of virtual water flow on provincial irrigation water use efficiency in China. The results show that virtual water flow is conducive to water resource conservation and irrigation WUE improvement when judged by the indicator of water productivity per unit of output (IWP), but the result is just the opposite when judged by another indicator of irrigation efficiency (IE). The evaluation framework proposed in this study can inspire research on agricultural water assessment, management, and regulation combining the physical and virtual water.