Optimizing land-use structure in the Jinghe River Basin under the goal of efficient water resource utilization postprint

Abstract: The efficient use of limited water resources remains a critical challenge in arid and semi-arid areas, where land-use structure exerts strong control over eco-hydrological processes. The Jinghe River Basin, located in the central Loess Plateau of China, is a typical semi-arid watershed that has undergone pronounced land-use transitions under the Grain-for-Green Program. This study developed a sub-basin-scale analytical framework to optimize the land-use structure in the Jinghe River Basin to improve water-use efficiency. Multi-source remote sensing data (2002–2022) were used to classify the dominant land-use structures based on K-means clustering, and to quantify the key hydrological indicators, including the runoff coefficient, evapotranspiration ratio, and water yield. The eco-hydrological thresholds and trade-off–synergy relationships were identified through boundary-line and correlation analyses, and were then incorporated into the land-use optimization model that was solved using LINGO and spatially simulated in R v.4.2.2 software. The results showed that the basin can be classified into grassland-dominated, cropland-dominated, and mixed cropland–forestland–grassland sub-basins with distinct hydrological responses. Moreover, the optimization results based on these boundary-line thresholds indicated structure-specific optimal land-use proportions for water-use efficiency: the grassland proportion was approximately 0.85 in grassland-dominated sub-basins, and the cropland proportion was approximately 0.63 in cropland-dominated sub-basins. In mixed cropland–forestland–grassland sub-basins, the optimal cropland and grassland proportions were approximately 0.33 and 0.41, respectively, with a composite utilization index of 0.35. These thresholds represented the balance points among the runoff regulation, evapotranspiration control, and water-yielding capacity under limited water resources in the region. By explicitly linking the land-use configuration with the hydrological efficiency through threshold-based constraints, this study provides a data-efficient operational framework for coordinated land–water management in the Loess Plateau, as well as other semi-arid river basins.