太湖流域土地利用变化的水文效应及其风险评价

Hydrologic Effects of Landuse Change and Its Risk Evaluation in Taihu Basin

以土地利用集约化程度高,城市化进程快的太湖流域为研究区,采用1985,2000年TM/ETM土地利用解译数据分析15 a来土地利用变化特征。运用长周期水文分析模型L-THIA,基于流域各气象站1971—2000年共30 a的日序列降水数据,计算1985,2000年这2个时段土地利用特征对地表径流的影响,评估土地利用变化的水文效应。研究结果表明,太湖流域土地利用变化主要表现为城镇扩展。全流域城镇扩展导致年平均地表径流增加1.14×10~8m^3,约为总径流量的2.9%。土地利用空间差异导致苏锡常区和浦东浦西区,分别增加了6.01%和3.91%。城市化高度发展的沪—苏锡常城市带,1985—2000年间城镇面积增加635.2 km^2,相应径流量增长6.5%。基于单元格网城市化水文效应风险评价结果显示,低、中、高风险区面积分别占评价区面积的37.5%,50%和12.5%。

This paper takes Taihu Basin as a study area since it has highly intensive land use and is subject to rapid urbanization. Historical landuse scenarios in 1985 and 2000 are analyzed to track landuse changes by interpreting TM/ETM images. The L-THIA （Long-Term Hydrologic Impact Assessment） model is applied to estimate hydrological effects of landuse changes from 1985 to 2000, based on daily precipitation records spanning 30 years （1971-2000）. Results show that the main trend of landuse change is the urban expansion in the basin, which results in an increase of runoff volume of 1.14× 10^8 m^3, about 2.9% of the runoff volume from entire basin. Hydrological response varies with the extent of landuse changes in different parts of the basin. In Su-Xi-Chang and Pudong-Puxi sub-regions, with larger extent of landuse changes, the landuse changes result in runoff volume increases of 6.01% and 3.91%, respectively. In Hu-Su-Xi-Chang city zone, with intensive urbanization, the urban area expands as much as about 635.2 km^2 and the runoff volume increases by 6.5 %. Based on runoff simulation and hydrological risk evaluation, the low, middle, and high risk areas are identified, which account for 37.5%, 50.0% and 12.5%, respectively.