试析淮河洪涝灾害成因

淮河地处我国南北气候、高低纬度和陆海交互作用的3种过渡带的重叠地区,是七大江河中洪涝灾害最频繁、灾情最严重的河流之一。究其原因有3大方面、9点内容。第一,与流域所处的特殊和不利的自然地理条件密切相关。①天气上,致洪暴雨天气系统众多且组合十分复杂;降雨时空分布很不均匀,降水量年际变化剧烈。②地形上,众多支流均在干流中游汇入,平原洼地占流域面积的60%,形成“关门淹”,难以下泄洪水和排除涝水。③土壤上,淮北平原和黄泛平原土壤土质紧密,水分不易下渗,最易发生涝渍。第二,与黄河661年之久的长期夺淮有着直接联系。④淮河不能直接入海,改流入江,下游地区水灾日益加重。⑤水系巨大变迁,原本统一的淮河划分为淮河水系和沂沭泗水系,且河系紊乱、河道淤废、排水不畅。⑥洪泽湖的逐渐淤积抬高和入湖河口段倒比降的形成,使中游河道下泄不畅。⑦淮河干流中下游河床比降小,甚至出现倒比降,洪水过程极其平缓。⑧黄泛区涝灾尤其突出。第三,不合理的人类活动加剧了洪涝灾害。⑨因不合理的人类活动而水土流失淤积河道及人为设障,使得河道的行洪能力下降。

Causes of Flood and Waterlogging Disasters of the Huaihe River

The Huaihe River catchment, located in the east of China, is a overlapped district of three kinds of transition zone, which are south and north climate, high and low latitude, interaction between land and sea. The Huaihe River is one of 7 long rivers of the most frequent and the most serious flood disaster in the whole country. The reasons are as the follows. Firstly, this is closely related with natural geographical disadvantages. The catchment has particular geography and climate conditions. Secondly, this is directly connected with the Yellow River pirating the Huaihe River for 661 years. Lastly, the reasonless human activities enhance the flood and waterlogging disasters. The reasonless human activities make soil and water loss and fill up the riverway. Human beings also set the obstacles in the riverway. All these reduce the riverway's ability to drain the flood.