Analysis of Landscape Ecological Mechanism of Impact of Coastal Geomorphological Structure on the Dissipation of Tidal Energy and the Function of the Disaster Prevention- Illustrated with Hangzhou Bay and Qiantang Estuary

Illustrated with Qiantang estuary , Hangzhou Bay, the relationship between structure of coastal geomorphology and dissipation of tidal energy were analyzed and the landscape ecological mechanism of watershed flood was studied based on the theory of the landscape ecology and quantitative assessment method of landscape characteristic index. By Correlation analysis and multiple linear regression analysis between reduction rate by tidal range and landscape characteristics index, such as fractal dimension and shape index, respectively, the close relation between the reduction rate by tidal range and the fractal dimension, shape index was indicated without considering the trend of changes in cross section and the depth. The results showed the greater fractal dimension and shape index were , the more reduction rate by tidal range and tidal energy loss were, which was extremely beneficial to urban flood prevention on the estuary and its upstream. However,the serious disturbance or destruction of large-scale development and construction on watershed landscape structure and form made river narrower, form singler, resistance tidal current was suffered reduced, tidal energy increased ,resistance flood was suffered from tidal current increased and drainage more difficulty accordingly et, which mainly caused the degradation of functions of watershed ecological disaster prevention and increase of urban flood.Finally, the scientific approaches of ecological reclamation which were beneficial to watershed disaster prevention and water environment were discussed.