A study on the green utilization model of port shorelines in silty-muddy coastal tidal flats

The sandy silt coast constitutes 54.1% of China's coastline, and as a significant type of sandy silt coastline and a pivotal area connecting land and sea, it is an essential carrier of the concept of a “vibrant coast”. The objective of this study is to address the long-term challenges posed by the relatively fragile ecology and inadequate green utilisation of port shorelines on sandy and silty coastal tidal flats. To this end, a green utilisation model has been developed to enhance “disaster mitigation and protection capacity, ecosystem vitality, and economic development vitality” through a synergistic approach. The study proposes a framework for evaluating the current situation, analysing problems, designing pathways, and establishing the model, and constructs a comprehensive evaluation index system comprising three levels of indicators. A comprehensive evaluation index system for the green use of the shoreline of beaches and harbours has been established, which comprises three levels of indicators. Indicator weights were determined using the entropy weight method, and coastal vitality levels were classified based on standardized criteria. This study focuses on a typical tidal-flat port shoreline in Dongying City, a representative area of silty coasts. As a core city of the Yellow River Delta Efficient Eco-economic Zone, Dongying provides reference value for similar regions. The level of green utilisation of tidal-flat port shorelines and the implementation effects of corresponding measures were systematically assessed. The results indicate that the low level of shoreline intensification and the degradation of ecosystem functions resulted in a relatively low coastal vitality index (0.541). The implementation of shoreline measures—including ecological shore protection, salt marsh restoration, oyster reef construction, and port-adjacent economic development—significantly improved disaster mitigation and protection capacity, ecosystem vitality, and economic development vitality, with index values increasing from 0.491, 0.614, and 0.496 to 0.572, 0.796, and 0.628, respectively. Consequently, the coastal vitality index increased to 0.672. Among the indicators, wave height attenuation rate, vegetation coverage rate, and demand for port-adjacent industries exhibited more significant impacts on coastal vitality. The establishment of the green utilisation model for tidal-flat port shorelines is conducive to efficient shoreline resource utilisation, environmental protection, and the coordinated development of disaster mitigation, ecology, and regional economy. The construction and application of the model have been demonstrated to enhance the level of green utilisation of the shoreline of the beaches and harbours in Dongying, and to enhance the vitality and high-quality development of the chalky-silt coast. The implementation of the green utilisation model of beach port shoreline demonstrates that the enhancement of coastal vitality constitutes a comprehensive, long-term governance project. In the utilisation of the beach port shoreline in Dongying, it is recommended that the construction standard of seawalls be improved, that the scale of ecological restoration of the coastal zone be expanded, that the structural transformation of the port industry be promoted and that the shoreline be utilised more intensively. These measures will enhance the safety of the shoreline flood prevention (tidal wave) embankment, the function of ecological services and the benefits of port utilisation. Furthermore, the level of green utilisation of the shoreline and the high-quality development of the economy and society will be promoted. The utilisation of green energy is of paramount importance in achieving high-quality socio-economic development.