The Impact of Non-point Pollutant Load of Land-use Changes in Taihu Basin

Abstract

This paper selects Taihu basin as a study area, with serious water pollution. Historical land-use scenarios for 1985, 2000 are analyzed to track the changes of land-use by interpreting TM/ETM image. The changes of runoff volume and non-point nutrient load are simulated due to land use change by using L-THIA (Long-Term Hydrologic Impact Assessment) model. The results express that there is a significant increase in urban and residential area by occupying farm land between 1985 and 2000, which leads to about 2.79% increase of the surface runoff volume in the whole watershed. The loads of total N and total P increase 467.952 t and 30.587 t respectively under urban and residential land use, decrease 384.885 t, 30.112 t for farm land, and increase 3.437 t, 0.093 t for forest land. For the whole study area, the loads of total N and total P increase 86.503 t, 0.568 t respectively. Non-point pollutant load response varies with the extent of land use changes in different parts of the basin, and in Suxichang, Huxi and PudongPuxi sub-regions, where the urban area increases more largely, the loads of total N and total P of urban and residential land use increase about 37.10%, 34.81% and 24.34% respectively.