Integrating agricultural land, water yield and soil conservation trade-offs into spatial land use planning

Since the implementation of the Grain for Green (GfG) project in 1999, the environment of China's Loess Plateau has been largely restored, and soil erosion has been controlled in places. However, new problems associated with food and river water resource security have arisen. Thus, to achieve sustainable development, it is critical to integrate agriculture and resource conservation with soil conservation. In this study, the Soil and Water Assessment Tool (SWAT) model was used to investigate the relationship between sediment load and water yield in the Yanhe watershed in the Loess Plateau. The results were as follows: (1) Sharp declines in agricultural land area (43.78%), water yield (38.48%) and sediment load (38.71%) have occurred since the implementation of the GfG project. (2) Based on the spatial heterogeneity of hydrological response units (HRUs), we proposed a simple method for land use planning that considers river water resources, agriculture and sediment loading and then established a balanced conservation scenario. Compared with the scenario in 2030 (planning scenario), the conservation scenario reduced the sediment yield by 6.4%, increased the water yield by 4.5%, and increased agricultural land by 80.1%. Our results can be used to support spatially targeted land use planning, which is beneficial for the sustainable development of the GfG project.