太湖流域北部潜在洪涝风险区分析及影响评估

Potential flood risk analysis and flood losses assessment in northern Taihu Lake Basin

太湖流域历来遭受严重的洪涝灾害,并且近年来有不断加重的趋势。本文选择太湖流域北部的无锡市作为典型研究地区,研究其洪涝的危险性并进行潜在损失评估。人类活动,包括修筑圩区、森林破坏、人口增长、城市化等,对这个地区的洪涝形势有较大的影响;自然条件的变化使河道水位升高,洪涝历时缩短,洪峰增高。本文选择不同回归年(2,5,10,20,50年),结合地理信息系统分析模型,计算了潜在洪涝危险区域和洪涝损失,主要结论为:(1)人类活动已经改变了自然的洪涝形势,增大了汇流和洪涝;(2)洪涝危险区与降雨中心有关;(3)筑圩成功地保护了圩内的土地,缩短了洪涝历时,增高了圩外河道的洪涝水位;(4)经济发展使洪涝损失增加。

The heavy floods in the Taihu Basin has showed increasing trend in recent years. In this work, a typical area in the northern Taihu Basin is selected for flood risk analysis and potential flood losses assessment. Human activities have strong impact on the studied area′s flood situation (as affected by the polders buildingup, deforestation, population increase, urbanization, etc.),and have made water level higher, flood duration shorter, and flood peaks sharper. Five different flood return periods (2,5,10,20 and 50 years) were used to calculated the potential flood risk area and its losses. The potential flood risk map, economic losses, and floodimpacted population were also calculated with main conclusions that: (1)human activities have strongly changed the natural flood situation in studied area, increasing runoff and flooding;(2)the flood risk area is closely related with the precipitation center;(3)polder construction has successfully protected land from flood, shortened the flood duration, and elevated water level in rivers outside the polders;(4)economic and social development have caused flood losses to increase in recent years.