Study of the Influence of the Deep-Water Channel Project in the Yangtze River Estuary on Ecological Landscape and Fractal Dimensions of Jiuduan Shoal Tidal Channels

The Jiuduan Shoal has the most extensive tidal channel system in the Yangtze River estuary diara, and the construction of the Deep-Water Channel Project in the Yangtze River estuary has had a significant effect on the distribution and morphology of tidal channels. Taking tidal channels in the Jiuduan Shoal in Yangtze River estuary as a research object, using remote sensing data which was extracted from 1997 to 2013, we analyzed the influence of the Deep-Water Channel Project in the Yangtze River estuary on the ecological landscape of Jiuduan Shoal tidal channels by using landscape indexes such as Total Class Area (CA), Number of Patches (NP), Patch Density (PD), Percentage of Landscape (PLAND), Landscape Shape Index (LSI), Fractal Dimension Index (FRAC), and Largest Patch Index (LPI). Graded tidal channels by using the principle of Horton - Strahler of image of 2013. We found that, in the 1st and the 2nd phase of the project, the proportion of the tidal channel area increased compared to the previous period, but by the end of the 2nd phase project in 2013, the proportion of the total landscape area made up of tidal channels accounted for less in successive years; NP, PD, LSI, and LPI fluctuated in the first phase of Deep-Water Channel Project, after this tidal channels of Jiuduan Shoal maintained the same trend, namely, the tidal channels aggregation degree decreased year by year. The distribution of tidal channels tended toward separation which shows that the tidal channels fragmentation is increasing year by year. By the end of the third phase of construction, the shape of the tidal channels became gradually different and tended to be more discrete. The shape complexity increased and the tidal channels became more and more mature and complicated and can be seen in the same grade of Jiuduan Shoal tidal channels, which on the left side of the dimensions change range are greater than the right, namely, the tidal channels on the left side are more complex than the right. In different grades of of tidal channels, the change range of the minimum width is little, but the maximum is quite large. There is little relevance between the changes in the width of the different grades of tidal channels and its fractal dimension difference values between the left and right sides. In different grades of tidal channels, whether left or right, the fractal dimension values increase with the average width and grade number of tidal channels.