In recent years, coastal reclamation has become an important way for coastal areas to ease the contradiction between supply and demand along the land and to develop and utilize marine resources. However, large-scale coastal reclamation will change the original natural properties of the sea area and cause changes in the surrounding hydrodynamic environment. Although coastal geomorphic features have a non-negligible impact on tidal energy loss and disaster prevention, few studies have paid attention to the intrinsic connection between the complexity of coastal morphology and the rate of tidal reduction. In this study, Hangzhou Bay is selected as the research object, and a model based on the correlation between coastal geomorphic complexity and tidal energy reduction rate is constructed by using the fractal geometry theory and the quantitative evaluation method of landscape complexity, and the model is used in the assessment of the impacts of reclaimed land in Zhoushan Islands on the geomorphic complexity and tidal energy dissipation. The results of the study show that the differential tide reduction rate is highly correlated with the complexity of islands, shoreline irregularities, curved boundaries and spatial morphology. In the application of the model, it was found that the traditional planning and design of reclamation led to a dramatic change in shoreline morphology, and with the significant reduction of the number of subdimensions D and the shape index S, the differential tidal reduction rate would be reduced by more than 88%, which also poses a significant threat to coastal and downstream estuarine bay disaster prevention. Finally, based on the above analysis, effective control indexes and scientific reclamation measures are proposed to provide theoretical basis for the efficient utilization and protection of mudflats in China.

Rivers play an important role in human production and life. On the one hand, rivers provide water for human production and life. On the other hand, when the river has too much water, it will bring flood disasters to human beings. Therefore, the prediction of river runoff is particularly important. Accurate runoff prediction can not only provide basic data for the allocation and operation of water resources, but also provide reference for flood control and waterlogging control of the basin. The formation process of runoff is affected by rainfall, underlying surface, human activities and other factors. The improvement of runoff prediction accuracy has always been a difficult problem in the hydrological field. Because the runoff is affected by many factors and contains a lot of noise, the prediction accuracy will be reduced by using the data containing noise. EEMD is a good tool to separate signal and noise. This method is used to preprocess the runoff series, decompose the runoff series into multiple IMF intrinsic modulus, and then use the ANFIS algorithm with strong nonlinear approximation ability to predict each IMF function, and then reconstruct the predicted data to improve the prediction accuracy of runoff. By comparison, the prediction accuracy of EEMD-ANFIS model is about 34% higher than that of ANFIS model.

Coastal reclamation can provide new space for agriculture, industry and urbanization, as well as new investment opportunities in coastal areas. As a result, both the length and proportion of artificial shoreline increased significantly. Meanwhile, the complexity of coastal morphology will be diminished by large-scale land reclamation. Although coastal geomorphic characteristics has a crucial impact on tidal energy loss and disaster prevention, little research has been conducted on the relationship between the tidal range reduction rate and coastal morphological complexity. This relationship is essential for predicting the impact of coastal complexity changes caused by accelerated land reclamation on tidal energy loss. Taking Hangzhou Bay and Zhoushan Islands as the research objects, combined with fractal geometry theory and quantitative assessment method of landscape complexity, the correlation between coastal geomorphological complexity and tidal distance reduction rate is analyzed, and A model based on the correlation of the tidal range reduction rate and geomorphological complexity is established. The model is applied to evaluate the effect of reclamation in Zhoushan Islands on the landscape complexity and dissipation of tidal energy. The results show that the tidal range reduction rate is reduced with the decrease of fractal dimension and shape index, indicating that the coastal geomorphologic complexity has an important effect on tidal energy loss. The efficient control indicators and scientific reclamation measures are discussed in this paper. This study provides new ideas for the analysis of the comprehensive impact of reclamation on coastal geomorphic characteristics and disaster prevention, and can provide guidance for the efficient utilization and protection of tidal flats.