1993年太湖流域的洪涝灾害及水利工程的作用

THE 1993 FLOOD DISASTER AND THE FLOOD CONTROL BENEFIT OF WATER CONSERVANCY PROJECTS IN TAIHU LAKE BASIN

1993年汛期太湖最高水位高居建国以来的第3位,仅次于1991年和1954年,达到4.51m(平均水位,下同),局部地区发生了洪涝灾害。本文对1993年太湖流域汛期的雨情和水情做了论述,并对1993、1991、1954年三个典型大水年的降雨和洪水特征作了比较。同时,还对洪涝灾害和水利工程的作用进行分析。太湖流域的雨季一般为5—7月,但是1993年汛期的降雨在时间上的分布有些异常。降雨集中在8月,而河道最高水位则出现在8月下旬。降雨的空间分布有以下3个特征:(1)上游地区的降雨集中在浙西山区;(2)太湖湖区的降雨量很大;(3)下游地区的降雨集中在淀泖和杭嘉湖地区。淀泖和杭嘉湖地区一些水位站的实测河道水位,比发生大洪水的1991年还要高。发生洪涝灾害的原因可归纳为,上游地区洪水来量大,当地的降雨强度高,以及下游河道排水不畅通。为了改进防汛调度和完善治理规划,需要对不同典型洪水年份的降雨和洪水模式做进一步研究。

In the flood season of 1993, Taihu Lake reached its high water level of 4. 51m, or the third highest one after 1949. Some areas of the basin were suffered from flood and waterlogging disaster. In this paper, the rainfall and flood regime, the comparison of rainfall and flood characteristics for typical flood years of 1993, 1991 and 1954 are illustrated. The flood and waterlogging disaster and the benefit of water conservancy projects are also analyzed. Rain season in the basin is from May to July. But in 1993, the temporal distribution of rainfall was unusual. The rainfall was concentrated in August and high water levels in rivers also appeared late in August. The spatial distribution of the rainfall was characterized by the follows: (1) The rainfall in the upper reaches was concentrated in the West Zhejiang mountain area; (2) The rainfall in Taihu Lake region was heavy; (3) The rainfall in the lower reaches was concentrated in Dianmao and HangJiahu regions. Water levels in the rivers of some hydrographic stations in Dianmao and Kangjiahu regions were higher than those in the heavy flood year 1991. Strong flood flow from the upper reaches, high rainfall intensity in the local area, low discharge capacity of the rivers in the lower reaches are the main causes of flood disaster. In order to improve flood control operation and harnessing plan, more researches should be done for some rainfall patterns and flood patterns of different typical flood years.