流域土地利用变化的长周期水文效应及管理策略

长周期水文效应作为不同强度暴雨事件的综合反映，对流域规划和管理决策非常重要。以太湖地区蠡河流域为研究区，通过解译1984年、1995年和2000年3个时段TM/ETM获得土地利用分布地图，分析其土地利用变化的模式，并基于研究区30年的降水序列，应用长周期水文分析模型L-THIA（Long-Term Hydrologic Impact Assessment），计算3个时段土地利用特征对暴雨地表径流的影响，分析不同土地利用类型水文效应的敏感性，在此基础上总结了减少流域水文效应的土地利用管理策略。分析结果显示，该区土地利用有明显变化，主要表现为水田、旱田向建筑用地的转化，从1984年到2002年，城镇及居民地扩展占流域总面积的4.199 4 ％，地表径流量增加了6.170 ％，不同土地利用方式的水文效应有较大差别，林地、湖滩湿地的敏感性最大，其次是水田和旱田。

THE LONG-TERM HYDROLOGIC IMPACTS OF LANDUSE CHANGE AND MANAGEMENT STRATEGY FOR LIHE WATERSHED OF TAIHU BASIN

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 water- shed management. By selecting Lihe watershed in Taihu Basin as a study area, this paper analyzed the lan- duse 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 in- creased 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 hydrolog- ic 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 impervi- ous area of urban and residential districts should be minimized in details. In addition, land-use planning at a watershed level should be concerned.