长江皖江段近期河道岸线变化的遥感调查

根据1954～2001年的航卫片遥感信息,对长江皖江段的岸线特征及变化进行了调查和分析。航卫片解译,长江皖江段南、北岸线长度分别为405.4km（右岸）和438.8km（左岸）,岸线总长844.2km。根据遥感影像特征和野外调查,将皖江岸带（线）划分为侵蚀岸（冲刷岸）、淤积岸和稳定岸3种类型,其中冲刷岸长426.4km,占岸线总长度的50.5%,左岸大于右岸;淤积岸长198.4km,占岸线总长度的23.5%;稳定岸长219.4km,占岸线总长度的26.0%。根据1954年、1969年、1975年和1986年4个时期的航片资料的对比解译,对1954～1969年、1969～1975年和1975～1986年3个时间段的岸线摆动幅度和速率进行了计算,从中发现,河道岸线的摆动主要是左岸侵蚀后退,段内岸线年平均变形强度在50m以上的有7处,在100m以上有2处。岸带变化的基本特征是:主河道长期右移,近期以左移为主;江心洲的平面变化复杂,汊道河段岸线变化强烈;鹅头形分汊河段演变具周期性特点。

RECENT BANK LINE CHANGE IN ANHUI SECTION OF CHANGJIANG RIVER BASED ON INFORMATION OF REMOTE SENSING IMAGES

The characteristics and dynamics of bank line in Anhui section of the Changjiang River were examined and analyzed based on the interpretation of remote sensed images.Aerial and satellite images acquired from 1954 to 2001 were obtained and the bank line was extracted and investigated.The results show that the total length of bank line in Anhui section of the Changjiang River is 844.2km,and the bank line length on the southern side and northern side are 405.4km and 438.8km,respectively.According to the image characteristics and field observation,the bank line was generally classified into three types.The first is eroding bank or scouring bank with the left side longer than the right.It has a length of 426.4km accounting for 50.5% of the total length.The second is depositing bank with a length of 198.4km accounting for 23.5%.The third is stable bank with a length of 219.4km accounting for 26% of the total length.The oscillating amplitude and rate of the bank line in the periods of 1954～1969,1969～1975,and 1975～1986 were estimated by comparative interpretation of aerial images acquired in the year of 1954,1969,1975,and 1986.The results demonstrated that the oscillation of bank line is mainly the erosion（collapses）and retreat of the northern bank.It was found that there are 7 sites where the annually mean deformation intensity is above 50m and another 2 sites are identified above 100 meters in this section.From the study,the basic dynamics feature of the bank in the Anhui section was understood.It revealed that the main water course was mainly right-shifting for a long time and turned to left-shifting recently,that the shape of the island in the river changed in a complex way,and that the bank line of the braided courses changed intensively and the evolution of goose-head shaped braided course shows a periodic feature.