Land Use Change Alters Hydrological Drivers of Soil Erosion in the Tapesco River Watershed, Zarcero, Costa Rica

Soil erosion is a major environmental concern in tropical mountain ecosystems where steep terrain, intense rainfall and dynamic land use changes contribute to the accelerated degradation of natural resources. This study assesses the spatiotemporal patterns of potential soil erosion in the Tapesco River watershed, a peri-urban territory located in Costa Rica's Central Volcanic Mountain Range, for the years 1986, 1998, 2011 and 2019. The Revised Universal Soil Loss Equation (RUSLE) was implemented within a Geographic Information System (GIS) framework, incorporating five critical factors: rainfall erosivity (R), soil erodibility (K), topographic slope length and steepness (LS), land cover (C) and conservation practices (P). By interpreting these factors as proxies of hydrological processes—such as rainfall energy, runoff generation, infiltration capacity and hillslope hydrological connectivity—the analysis provides insight into how water-driven erosion mechanisms evolve under land use change. The results reveal significant changes in erosion rates strongly associated with land use transitions and climatic variability over the study period. Forested and pasture lands consistently exhibited lower erosion rates, whereas areas under annual crops and steep slopes were subject to markedly greater soil loss. A substantial increase in erosion was observed between 1986 and 1998 followed by a partial recovery by 2019, corresponding with a decline in agricultural land use and the expansion of forest and pasture areas. Furthermore, an erosion risk exposure map identified that 28.9% of the watershed—mainly in the eastern and upper watershed—remains highly vulnerable to erosion. These findings underscore the value of spatially explicit erosion modelling as a critical tool for informing sustainable land management and targeted soil conservation efforts in fragile tropical mountain landscapes. These findings demonstrate how shifts in hydrological processes—particularly runoff concentration, rainfall–runoff response and surface–vegetation interactions—mediate erosion dynamics over time. Overall, the study highlights how soil erosion modelling can improve understanding of hydrological functioning in tropical peri-urban landscapes and provide actionable information for integrated soil–water management.