Soil Erosion Modeling of Kinmen (Quemoy) Island, Taiwan: Toward Land Conservation in a Strategic Location

Kinmen Island, historically known as Quemoy, holds significant historical and geopolitical importance due to its strategic location in the Taiwan Strait, just a few kilometers from the Chinese mainland. This study presents the first comprehensive assessment of soil erosion and deposition on Kinmen, providing a scientific foundation for future land conservation and sustainable development initiatives. It also addresses the underrepresentation of small-island environments in soil erosion modeling by adapting the Revised Universal Soil Loss Equation (RUSLE) and Unit-Stream-Power-based Erosion Deposition (USPED) models for coarse-textured soils under limited rainfall conditions, offering insights into the reliability and limitations of these models in such contexts. The rainfall–runoff erosivity factor ( R m ) was derived from precipitation data at four stations, while soil samples from ten locations were analyzed for the Soil Erodibility Factor ( K m ). Topographic factors, including the Slope Length and Steepness ( LS ) and the Topographic Sediment Transport ( LS T ) factors, were computed from a 20 m DEM (Digital Elevation Model), and the Cover-Management Factor ( C ) was obtained from land use classification. The RUSLE estimated a mean soil erosion rate of 2.17 Mg ha −1 year −1 , while the USPED results varied with parameterization, ranging from 0.87 to 3.79 Mg ha −1 year −1 for erosion and 1.39 to 6.51 Mg ha −1 year −1 for deposition. The results were compared with studies from the neighboring Fujian Province and contextualized through two field expeditions. This pioneering research advances the understanding of erosion and deposition processes in a strategically located island environment and supports evidence-based policies for land conservation, contributing to SDG 15 (Life on Land) and SDG 13 (Climate Action).