Distribution of Wetlands of Mid-channel Bars and Islands in Yangtze River Mainstream and Its Influencing Factors
Widespread in the Yangtze River mainstream,wetlands of mid-channel bars and islands caused by seasonal inundation have important ecological effects such as protecting biodiversity and purifying the environment.These wetlands are regarded as important material basis for ensuring ecological security in the Yangtze River basin.The distribution and dynamics of wetlands in the Yangtze River basin and their ecological significance have received a lot of attention,while the wetlands of mid-channel bars and islands in the Yangtze River mainstream,an important component of Yangtae River basin wetland,has been less studied and reported.In this study,Google Earth high-resolution remote sensing images were used to visually interpret and extract the wetlands of mid-channel bars and islands,GIS methods were adopted to extract channel morphological parameters and correlation analysis as well as ordered logistic regression analysis were used to reveal the distribution of these wetlands.Also,the influence of channel morphology on the distribution of the wetlands was explored.The results were as follows.The spatial distribution of the wetlands demonstrated four sections,namely,Yibin-Zhongxian section,where only small and medium-sized wetlands were distributed;Zhongxian-Yichang section,where no wetlands were distributed;Yichang-Jiujiang section,where small and medium-sized wetlands dominated;and Jiujiang-Yangtze River Estuary section,where wetlands of all area level were widely developed.In the last section,the small and medium-sized wetlands were denser than in the immediately upstream Yichang-Jiujiang section,while the large-sized wetlands were almost the same as in the Yichang-Jiujiang section.The number of small-sized wetlands in the study area was larger than that of large-sized wetlands.Small-sized wetlands were less sensitive to channel morphology than the large-sized wetlands.The area of the wetlands had a significant positive relationship with channel width and the difference in channel width,while the area had a significant negative relationship with difference in shoreline length.This implied that a wider,straighter,and more symmetrical river channel was conducive to the development of large wetlands of mid-channel bar.
wetlandmid-channel bars and islandsYangtze Riverspatial distributionchannel morphology
NETL
NSTL
万方数据
