Land-use/-cover change spatial patterns and their impacts on sediment charge in the Longchuan River catchment, south-western China

Abstract

Many previous studies indicate that land-use/-cover change (LUCC) has effects on hydrological processes at the catchment level. The spatial pattern of LUCC (LUSP) may have different influences on hydrological processes. In this article, a mountainous catchment with different micro-topographic and micro-climatic types in the south-west of China was selected to study the LUSP and its impacts on annual sediment charge (ASC). Remotely sensed images from the Landsat Multi-Spectral Scanner (MSS), the Thematic Mapper (TM), the Enhanced Thematic Mapper Plus (ETM+) and the China–Brazil Earth Resource Satellite (CBERS) were used to retrieve land-use/-cover conditions for the past three decades. The multispectral operational method for TM/ETM+ and spectral threshold methods for MSS and CBERS were employed to retrieve the topographic shadows. LUCC was analysed in different topographic areas, proximities to streams and micro-climate areas. The impacts of LUCC on ASC were then calculated and analysed by the weights of different land-use/-cover types in different spatial zones. The results showed that LUCC makes significant contributions to changes in ASC, especially in areas with a slope of 6°–35°, higher elevation areas (>1650 m ASL) and areas close to rivers (buffering distance less than 3000 m). In these areas, forest and grassland experienced greater changes than other areas, which indicate that the changes in ASC may be associated with the reforestation efforts since 1989.