太湖平原武澄锡虞区水系结构及水文连通性变化分析

Change of River Structure and Hydrological Connectivity in Wu-Cheng-Xi-Yu Region of the Taihu Lake Plain

河网水系在太湖平原地区水源供给、洪涝排泄、水质净化过程中发挥着重要作用,但近几十年来该地区城镇化迅速,土地利用改变、水资源过度开发等人类活动导致河网水系衰减,水文连通受阻,并引发一系列洪涝与水环境问题。为此,以太湖平原武澄锡虞区为例,构建水系结构与连通性评价指标,分析该地区1960s~2010s水系结构和水文连通性变化特征。研究表明该地区:(1) 1960s~2010s水系不断衰减,武澄锡虞区河网密度、水面率、河网发育系数分别降低了22.94%、25.09%和22.35%,河网复杂度急剧下降,其中武澄锡区河网衰减程度大于澄锡虞区。(2)水文连通性存在先下降后上升发展趋势,1960~1980年,该地区的平均水文连通性为0.89,1980~2000年平均水文连通性降至0.82,2000~2016年平均水文连通性恢复到0.91。(3)城镇化发展导致水系结构大幅度衰减,水系结构主干化以及水利工程建设使得水文连通性下降,而疏浚、拓宽河道在一定程度上可提高区域水文连通性。本研究将为平原区水系利用与保护提供一定的支持与参考。

The river system plays an important role in the water supply,flood discharge and water purification process of the Taihu Lake Plain. Recently,the urbanization of the Taihu Lake Plain had developed rapidly. A series of human activities such as land-use change and over-exploitation of water resources had resulted in changes in rivers and lakes,and hydrological connectivity had been affected. Furthermore,all these lead to a series of flood and water environment problems. Taking Wu-cheng-xi-yu Region of Taihu Lake Plain as an example,this paper discussed the changes of water system structure and hydrological connectivity in the 1960s-2010s by constructing river system structure and connectivity indicators. The results show that: 11960s-2010s,With the continuous attenuation of river system,the development coefficient of the river network density and surface rate in Wu-Cheng-Xi-Yu Region decreased by 22. 94% and 25. 09% and 22. 35% respectively,and the complexity of the river network decreased sharply. Among them,the attenuation degree of the river network in Wu-Cheng-Xi region was greater than that in Cheng-Xi-Yu Region. From 1960 to 1980,average hydrological connectivity of the region was 0. 89. Average hydrological connectivity of 1980-2000 period fell to 0. 82. Average hydrological connectivity returned 0. 91 in 2000-2016,which showed a trend of increasing first and then decreasing.Hydrological connectivity between water stations has increased since the 1990s. 3 The attenuation of the river structure and the artificial hydraulic regulation artificial hydraulic regulation made the hydrological connectivity decline. And this study will provide support and reference for the utilization and protection of river system in the plain area.