Impact assessment of land use and land cover change on soil erosion at Laonung watershed in Taiwan

Soil erosion poses an environmental threat to the ecosystem functions. Land use and land cover (LULC) changes are largely responsible for soil erosion severity. This study aimed to evaluate the impacts of LULC on soil erosion and erosion distribution in the Laonung watershed over the study period (1995-2016). To model the response of soil erosion to LULC changes, a physiographic soil erosion-deposition (PSED) model is employed, which incorporates Geographic Information Systems (GIS) with rain-runoff models and erosion-deposition models. The results revealed that over a three period (1995, 2008 and 2011), agricultural land, grassland, bare land, water bodies, and other land uses increased, whereas forest land declined by 11,424 x 104 m2 (2008 relative to 1995) and 16,159 x 104 m2 (2011 relative to 1995). In addition to the land use, landslide was considered as a land cover in this study. As landslides dramatically alter the land cover dynamics of mountainous regions in Taiwan. The landslide areas substantial changed over the period 2003 to 2016 (847 x 104 m2-9474 x 104 m2). The significant increase in landslide area together with the abrupt dynamics in LU severely aggravated soil erosion. Compared with the period of primeval forest, total soil erosion increased from 29,295 x 104 m3 to 102,597 x 104 m3 (1995-2011 LU) and 205,833 x 104 m3 (LULC). The study has illustrated how LULC changes strongly affects soil erosion.