Regional blue and green water-saving potential and regulation paths for crop production: A case study in the Yellow River Basin

A comprehensive assessment of the regional water-saving potential (WSP) for crop production is the foundation for setting targets, formulating strategies, and implementing management measures for agriculture. Water footprint (WF) for crop production is a well-known indicator of blue and green water consumption and an effective tool for evaluating blue and green WSP in crop production. The WSP evaluations based on crop WF primarily rely on crop redistribution (CR) and the crop WF benchmark (WFB). The CR can be completed relatively quickly, but the WSP is limited. In contrast, reaching an area’s maximum WSP is possible with WFB, but it requires long-term and multi-aspect inputs. However, existing evaluations of regional crop WSP are often based on a single methodology, and the results are various, which confuse the policymakers at times. This study estimated both blue and green WSP of wheat and maize based on two approaches—crop redistribution (CR) and crop water footprint benchmark (WFB)—at the county level in the Yellow River basin (YRB) in different hydrological years. The WSP was 7–11% based on CR, whereas 17–24% based on the crop WFB. The green WSPs were larger than blue WSPs. Over half of counties had larger WSP based on the WFB. These values vary with the crop, region, and hydrological year. The analysis emphasises the importance of considering both blue and green water, and quantitatively comparing different water-saving methods when evaluating regional crop WSP.