太湖流域土地利用变化的营养盐输出响应模拟

通过解译1985年、1995年和2000年3个时段TM／ETM影像，分析太湖流域80年代以来的土地利用变化特征。采用不同土地利用类型产出营养盐实测参数与分布式水文模型相结合的思路，建立基于单元格网的流域营养盐污染估算模型，定量评估太湖流域土地利用变化对氮素输出的影响。研究结果显示，模型模拟径流量及总氮输出量与实测值吻合良好；自1985年到2000年，太湖流域城镇面积扩展了40．38％，增加量占太湖流域总面积的3．88％；在1980～2000年的雨情下，全流域土地利用变化导致产流量平均增加4．11％，TN输出量平均增加5．35％，最高值为21．62％，各年差异与降雨分布和雨情特征有关；受土地利用变化空间差异影响，在城镇快速扩展的苏锡常地区和浦东浦西地区，土地利用变化导致TN输出量平均增加17．11％和10．72％，最高可达60．43％和28．689%。

Simulation of Nutrient Fluxes Response of Land Use Change in Taihu Basin

Historical land use scenarios for 1985, 1995, and 2000 were analyzed to track land use change of Taihu basin by TM/ETM image explanation. A cell-based non-point source pollution model is developed by combining the distributed hydrological model with the runoff concentration parameters of different land use types, and nitrogen utputs response of land use change are estimated by simulating the runoff volume and nitrogen fluxes usinglong-term rain records from 1980 to 2000. The results express that the modeled runoff volume and nitrogen outputs match well with the observed ones. For the entire basin between 1985 and 2000, the urban area increased about 40.38%, about 3.88% of the whole basin area. The land use changes result in runoff volume increase of 4.11% on average. Total nitrogen outputs increase 5.35% on average and 21.26% on maximum respectively. Nutrient output response varies according to the extent of land use changes in different parts of the basin and rain feature. In Suxichang and Pudongpuxi sub-regions, with more extent of land use changes, total nitrogen outputs increase 17. 11% and 10.72% on average respectively, and 60.43% and 28.68% on maximum.