Global water scarcity is intensifying, and agriculture remains the main consumer of freshwater. Many studies have assessed agricultural water productivity (WP) in major farming regions. While previous studies have mainly assessed overall efficiency or single crops, crop-specific dynamics within double-cropping systems remain insufficiently understood. This study quantifies the spatial patterns and stage-wise changes in winter wheat and summer maize WP in the North China Plain based on five representative years (2000, 2005, 2010, 2015, and 2019) and examines their climatic and anthropogenic drivers. The Optimal Parameter-Based Geographical Detector (OPGD) model was used to assess the explanatory power of influencing factors, and the Multi-scale Geographically Weighted Regression (MGWR) model was applied to capture spatially heterogeneous relationships. Wheat WP ranged from 0.56 to 1.30 kg m−3 and showed a significant increasing trend, whereas maize WP ranged from 0.89 to 1.72 kg m−3. Both climatic and anthropogenic factors exhibited pronounced spatial heterogeneity. Beijing and Tianjin were classified as anthropogenic-dominated zones, while several cities in Henan displayed crop-specific dominant drivers. Fertilizer application was negatively associated with WP in multiple regions, indicating declining input efficiency under intensive management. These findings support irrigation zoning and differentiated water allocation strategies, contributing to sustainable intensification and progress toward water-related (SDG 6) and food security (SDG 2) goals in intensive double-cropping regions.
Cao et al. (Sat,) studied this question.