鄱阳湖冬季水位变化特征及其淹没影响分析

Analysis of characteristics of water level variation and influence on inundation in Poyang Lake in winter

非汛期洪水对湖泊湿地植被结构、生态系统稳定性、栖息环境质量等具有重要的潜在影响。为探究鄱阳湖非汛期洪水规律,基于星子站1953—2013年冬季(12月至次年2月)水位数据,从涨水幅度、涨水持续天数、日均涨水速率等角度分析了近60 a冬季洪水特征,结合MODIS遥感影像探讨了鄱阳湖冬季典型洪水事件的淹没规律。结果发现:2003年后鄱阳湖冬季水位相对2003年前偏低,呈下降趋势;鄱阳湖共发生冬季洪水事件208次,冬季洪水最大涨水幅度6.69 m,涨水持续天数最长达31 d;大部分冬季洪水事件涨水幅度小于2 m、涨水持续天数小于20 d、日均涨水速率低于20 cm/d;短历时慢速洪水、中速洪水为鄱阳湖冬季洪水事件的主要类型;在冬季涨水时期,与鄱阳湖南部湖区相比,鄱阳湖北部、中部受影响较大,淹没范围明显增加。研究表明:鄱阳湖非汛期洪水主要以短历时、缓慢涨水为主,冬季涨水对湖泊中北部低位滩地淹没影响较明显。鄱阳湖冬季水位下降是多因素结果,其中,在2004—2013年人类采砂活动导致的湖盆变化的影响显著,研究结果可为鄱阳湖湿地保护和水资源管理提供参考。

Floods during dry seasons have important potential impacts on the vegetation structure of lake wetland,ecosystem stability,and habitat quality.In order to explore the flood of Poyang Lake during dry seasons,this paper analyzes the characteristics of winter floods in recent 60 years using the rising amplitudes,durations and average rising rates based on the water level of Xingzi station in winter(from December to February)between 1953 and 2013.Besides,the inundation characteristics of typical winter floods are also discussed by virtue of MODIS remote sensing images.The results shows that the average and minimum water levels of Poyang Lake in winter after 2003 were lower than those before 2003,with a significant drop in the maximum water level and rising amplitude.There were 208 winter flood events with the maximum rising amplitudes of 6.69 m and the maximum flood duration of 31 days in Poyang Lake.For most winter floods of Poyang Lake,the rising amplitudes are below 2 m,and the rise durations are less than 20 d,while the average rising rates are lower than 20 cm/d.Short-duration with slow-speed and medium-speed floods are major types of winter floods in Poyang Lake.Compared with the southern part,the northern and central region of Poyang Lake are sensitive to winter floods with a notable increase of inundated areas.Studies have shown that winter floods in Poyang Lake are featured with short duration and slow water rise.Winter floods have a significant impact on the inundation of lowland in the north-central part of the lake.The water level decline of Poyang Lake in winter is a multi-factor result,and the impact of human sand mining activities on lake basin changes is remarkable in 2004-2013.The research results are expected to provide reference for wetland protection and water resource management in Poyang Lake.