Simulation of Soil Erosion Responses to Land-Use Changes at A Catchment Scale

Soil erosion is a major environmental threat to ecosystem functions, especially to the sustainability and productive capacity of land such as agriculture. Land-use change on one hand is among the key influential factors of soil erosion. Therefore, modelling the impact of land-use changes on soil erosion in watersheds is crucial in soil and water resource planning and management. In this study, a physiographic soil erosion-deposition model (PSED), which integrates Geographic Information System (GIS) with rainfall-runoff model and erosion-deposition model is applied to simulate the response of soil erosion to land-use changes. Being paired with GIS, the model can evaluate huge hydrologic and physiographic datasets without the need for simplification. Land-use changes from 1995 to 2011 in Laonung watershed, Southern Taiwan were used for the analysis. It was observed that agricultural land, grassland, bare land, built-up areas, unoccupied land expanded, at the expense of forest land. Consequently, resulting in a substantial amount of soil loss in the study area. Five typhoon events from 2002 to 2019 were used to simulate the effect of land-use changes on soil erosion. The results show that even the slightest changes in land use had a significant impact on the regional soil erosion with increasing rates ranging from 59-555%, 43-546%, 52-608%, 48-609%, 51-601% for 1995 2011 land-use changes during 2002, 2009, 2011, 2017, 2019 typhoon events, respectively. The proposed approach can be applied in similar watersheds as an effective tool to enhance land-use monitoring and management of watersheds.