基于哨兵1号的洪水淹没面积监测

准确及时得到洪水淹没区域及淹没面积,对于抗洪救灾有着重要意义。洪涝灾害时基本为阴雨天,光学遥感无法监测到洪水淹没有效区域,使时效性和准确性下降,利用星载合成孔径雷达(SAR)则不受云雨影响、可全天候观测,及时获得下垫面洪水淹没区域及面积,可为洪水监测提供有力保障。本文以2016年7月长江流域洪水为例,应用哨兵1号(Sentinel-1)星载合成孔径雷达结合阈值法和伪彩色合成等方法,在GIS工具下对长江流域部分湖泊和长江干流等提取水体区域,得到淹没范围和分县淹没面积,进行洪水淹没区变化分析,并与同期MODIS影像监测结果进行对比验证。结果表明基于哨兵1号的水体提取方法和淹没面积的计算可行。

Survey Study of Flood Inundation Areas Based on Sentinel 1

It is significant to obtain the flood inundation area accurately in time in terms of fighting against flood disasters. But it is often rainy and cloudy when flood disaster happens, so the optical remote sensing is not able to survey the flood inundation area, which will decrease the timeliness and accuracy. The Synthetic Aperture Radar (SAR) can be applied to determine the flood inundation area and flood regions of the underlying surface in time, for it is not influenced by clouds and rains and can offer all weather observation. Therefore, SAR can provide a strong guarantee for flood survey. In this article, the flood disaster in the Yangtze River region occurred in July 2016 is used as an example, in which the Sentinel 1 SAR data, along with threshold and RGB band methods, are used, by means of GIS tools, to successfully extract the water areas from some lakes of the Yangtze River as well as the main stream of the Yangtze River. As a result, the submerged range and the flood area of each county are obtained. The flood area is analyzed and compared with the results of the MODIS monitoring in the same period. The results show that the method of water extraction and flood area calculation based on Sentinel 1 is effective, which can be the basis of researches on the application of Sentinel 1 data in flood disaster evaluation.