基于遥感影像的鄱阳湖2020年汛期灾情分析

Analysis on inundation condition in Poyang Lake during flood season of 2020 based on satellite image

2020年汛期鄱阳湖遭遇了超历史大洪水,湖区多站出现超历史洪水位,湖口站最高水位达22.49 m,昌江中洲圩、问桂道圩及修河三角联圩等多个圩堤出现决口险情,鄱阳湖运用185座单退圩堤分蓄洪水。选取1998~2020年汛期7~9月湖口站的日均水位序列进行水位特性分析,结果表明湖口站2020年汛期7~9月平均水位为20 a来最高。对收集到的2020年6月20日至8月31日Sentinel-1遥感影像进行预处理后,采用改进的SDWI水体指数法提取研究区水体面积,研究分析了水体面积与湖口站日均水位之间的相关关系及水体面积时空变化情况,并重点分析了圩堤决口后、单退圩堤分蓄洪运用后的水体淹没情况。最后初步分析了鄱阳湖2020年汛期湖口站未超保证水位、避免湖口附近蓄滞洪区运用的原因。研究成果可为未来鄱阳湖防洪提供借鉴。

In the flood season of 2020,Poyang Lake suffered from a super-historical flood,and several hydrological stations in the lake area showed super-historical flood level,the maximum water level of Hukou station reached 22.49 m.The Zhongzhou polder,Wenguidao polder in Changjiang River and Sanjiaolian polder in Xiuhe River all breached.185 semi-restoration polders were used to store flood water,and Jiangxi Province suffered serious flood disasters.In this paper,the daily average water level series of Hukou station in the flood season(from July to September)from 1998 to 2020 were selected for analysis.It was found that the average water level of Hukou station from July to September in the flood season of 2020 was the highest in the past 20 years.After preprocessing the collected Sentinel-1 remote sensing image from June 20 to August 31,2020,the improved SDWI water index method was used to extract the water body area in the study area.The correlation between water area and the daily average water level of Hukou station and the temporal and spatial variation of water area were analyzed,and the inundation condition after the polder dike breach and use of semi-restoration polder was analyzed.Then,the reasons why the water level of Hukou Station did not exceed the guaranteed water level and avoidance of use of flood storage and detention areas near the Hukou Station were preliminarily analyzed.The research results can provide reference for future Yangtze River flood control.