围垦对鄱阳湖洪水位的影响及防治对策

Impacts of Reclamation on the Flood Regime in Poyang Lake and Countermeasures

略述了鄱阳湖围垦的简要历史和现状，分析了近５０年来洪水位的演变趋势，指出围垦使鄱阳湖面积和容积缩小，调蓄功能衰退，以致水情不断恶化，洪峰水位逐渐上升，高水位的出现频率明显加大，致灾洪水越来越频繁．在此基础上，将围垦对洪水位的影响进行了分析计算。

Poyang Lake is the largest freshwater lake in China with a catchment area of 162000km^2. The only outlet to the Changjiang River is at Hukou. The flood regimes in the lake are mainly controlled by the Changjiang River and the 5 tributaries to the lake. The reclamation in the lake area may be traced hack to the Song Dynasty. The benefits of reclamation to mankind were inevitably hampered due to the frequent natural flooding. It was estimated that an area of 15. 8 km^2 had been reclaimed before 1949, among which the standards of many dykes were too low to resist heavy flooding. After 1949, the economic growth as well the urgency for eliminating popular snail fever in the lake beach triggered the large-scale reclamation movement around the lake. Up to 1995, statistics show that a total area of 1466. 9km^2 has been reclaimed, which brought a series of unfavorable influences on the flood regimes of the lake, such as: (1) the shrinkage of lake area and capacities, (2) the deterioration of flood regulating and functioning, and (3) the ascending of peak floods and corresponding frequencies. The impacts of reclamation on the flood regime of Poyang Lake are analyzed. Five represent- ative flood years, i. e., 1954, 1962, 1976, 1983 and 1995 are selected as backgrounds for estimation. Comparisons are made between the calculated and observed flood characters of certain typical flood years under present reclamation conditions. Furthermore, the supposing flood peak changes conditioning future reclamation/de-reclamation based on 1954-type flood processes under present situation are given. The more de-reclamation, the more will flood regime be alleviated.