基于RS的辽河下游牛轭湖50年演变研究

辽河下游与入海口处是中国重要的湿地区域之一,该地区河流众多,河曲发育,平原上遗留有很多废河道和牛轭湖。利用50年来6个不同时相的美国锁眼卫星KH-4A和Landsat卫星系列MSS、TM、ETM、OLI-TIRS遥感影像及研究区1:250000地质图,采用目视解译和计算机图像处理相结合的方法,对遥感影像进行几何校正、镶嵌、裁剪以及图像增强等处理后,进行河道专题信息提取,结合相关历史资料,分析了1963—2013年辽河下游50年期间牛轭湖的演变。结果表明:过去50年来,辽河下游在河道形态、河漫滩土地利用等方面都发生了重大变化;人为因素对牛轭湖演变的影响增大,从20世纪80年代开始,区域内水利工程建设和农田改造等人类活动间接影响着牛轭湖的演变;近年来,辽河下游牛轭湖演变速度呈现变缓趋势,1963—1984年期间,河曲快速发育并演变成牛轭湖;1984—2002年期间,河曲变化减缓;2002—2013年期间,牛轭湖的演变基本趋于停滞状态。

EVOLUTION OF OXBOW LAKES OF LIAOHE RIVER OVER LAST 50 YEARS BASED ON REMOTE-SENSING METHOD

The lower reaches and estuaries of Liaohe River is one of the important wetland area of China, there are many meanders as well as abandoned channel and oxbow lakes in the plain. The author analyzed the evolution of oxbow lakes in the lower reaches of Liaohe River from 1963 to 2013 by utilizing the American Keyhole satellite KH-4 and Landsat MSS, TM, ETM, OLI-TIRS remote-sensing images of 7 different periods in the past 50 years and the geological map in scale of1: 250000 for theresearch area. The method combines visual interpretation with computer image processing, by extracting the thematic information of river channel after geometric correction, mosaic, crop and image enhancement to the remote-sensing images, and combining the related historical records. The results show that great changes have taken place along the lower reaches during the past 50 years in river form and floodplain utilization. The human activities affected increasingly the evolution of oxbow lakes directly or indirectly after 1980s, such as construction of regional water conservancy project and farmland improvement. The oxbow lakes evolved slowly in recent years in the areas, while meanders evolved rapidly during 1963 - 1984 and stabilized slowly during 1984 - 2002.