江苏里下河地区洪涝灾害演变趋势与成灾机理分析

Flood Changing Trend and Flooding Mechanism in Lixiahe Region,Jiangsu,China

江苏里下河地区是相对封闭的水网地区,洪涝频繁。研究该地区洪涝演变趋势和成灾机理对区域防洪减灾具有重要意义。里下河地区洪涝演变趋势表现在洪涝类型的多样性,高水位日益频繁、高水位发生机率加大,致灾暴雨频率增大等方面。在自然成因方面,流域暴雨是成灾的主要原因,锅底洼的形态是洪涝发生的地貌大背景,水系的复杂格局也加剧了洪涝的程度和频度。在人类活动方面,不合理的圩垸垦殖导致湖荡萎缩,减弱了水体调蓄能力;闸坝建设引起河道淤积、排涝能力降低致使洪水位趋高;城镇化改变下垫面性质的水文效应也是洪涝频繁的主要因素。

Located in the north Jiangsu, East China, Lixiahe region is a relatively closed region with frequent flood, it is of great importance to discuss flood changing trend and flooding mechanism for the mitigation strategy in Lixiahe region. Results based on the analysis of the historical flood in the region show that flood types are complex, which have a diverse characteristics, high water level occurs frequently, recently, especially with high reoccurrence interval of flood water level, and frequency of the causative storm is increasing significantly. We view the flooding mechanism of the Lixiahe region a coupling effect of the natural factors and human factors. For natural factors, certainly the storm precipitation plays the most basic role in the flooding mechanism, the bowlshaped topography is the main background of flood, and the interlaced complex water system makes flood appear more easily. And more, irrational anthropogenic activity is another part for the flooding mechanism, the building of dyke and embankment greatly decreases the lake area, which evidently weakens the capacity of the lake and water body, accumulation of mud resulting from dam construction and the low standard of drainage system makes the continuance of high flooding water level, and the increase of runoff coefficient caused by hydrological effect of urbanization like the increase of imperviousness with the sprawl of urban also leads to great flood in Lixiahe region. Therefore, to ensure the sustainable development for this region, both natural and social factors for flood mitigation should be considered scientifically.