Revealing the complex relationship between urbanization and soil erosion by water in China

Urbanization alters land use patterns, reducing soil erosion through surface hardening, while simultaneously increasing erosion due to enhanced agricultural activities and surface disturbance. However, the complex relationship between urbanization and soil erosion remains insufficiently studied. This study uses a system dynamics (SD) model and a future land use simulation (FLUS) model to simulate the land use pattern in China and quantifies the effects of urbanization on soil erosion by integrating the Revised Universal Soil Loss Equation (RUSLE) with a counterfactual non-urbanization scenario analysis. Further, a multiregional input-output analysis (MRIO) is used to investigate the cross-regional effects of urbanization. The findings suggest that urbanization generally reduces soil erosion in most provinces, especially in key agricultural regions and areas highly vulnerable to erosion, such as Liaoning, Jilin, and Sichuan. The reduction is primarily attributed to changes in steep-slope cropland, highlighting the need for targeted management strategies in these areas. Moreover, our study also indicates that provinces with higher economic development indirectly contribute to soil erosion in other provinces due to consumption patterns under the actual and non-urbanization scenarios. Although urbanization mitigated the overall cross-regional impact on erosion in terms of absolute quantity (decreased 14.54 million tonnes), it intensified the erosion inflow of Hunan (1.94 %), Guangdong (3.53 %), and Fujian (2.63 %) from Guangxi and Sichuan. Our research highlights the comprehensive impacts of urbanization on soil erosion, providing new insights on soil erosion prevention from a complex social-ecological system perspective and policy making at national and provincial scales.