Abstract: Landuse change, dominated by an increase in urban and residential area, has lots of impacts on water environment, such as increasing downstream flooding, decreasing groundwater supply and drying wetlands and so on. So it's very important to analyse hydrologic impacts of land use change for watershed sustainable development. The longterm hydrologic impacts analysis is focused on the average impact, rather than an extreme year or so, and is thus very useful in a decisionmaking in landuse plan and watershed management. By selecting Lihe watershed in Taihu Basin as a study area, this paper analyzed the landuse changes and its longterm hydrologic impacts based on TM/ETM explanation and L-THIA model . The result shows that there is a significant increase in urban and residential land uses between 1984 and 2000, accounting for about 4.199 4% of the whole watershed area. The urban and residential landuse increased mainly by expanding to farm land. Due to the land use change, surface runoff volume increased about 6.170% of that of whole watershed. Different land use types have different sensitivities to hydrologic impacts from land use change. The forest and wetland are more sensitive than paddy field and dry farm land. Based on these analysis results, some watershed landuse strategies are suggested. For decreasing the impacts of landuse change, future development should be encouraged on areas with low hydrologic sensitive landuse type and the high hydrologic sensitive landuse patch should be protected. The impervious area of urban and residential districts should be minimized in details. In addition, landuse planning at a watershed level should be concerned.

Key words: landuse, Lihe River, Taihu Lake Basin, hydrologic impact, watershed management