[Sea-land hydrological connectivity of coastal wetlands based on water salinity and hydrological structure.]

In this study, with water salinity as the core index, sea-land hydrological connectivity index was constructed by integrating the hydrological structure connectivity index (water surface ratio, intake and outtake density, sea-land distance, and ditch distance). Based on multi-scale spatial analysis, we carried out the spatial quantitative analysis and classification of sea-land hydrological connectivity in the study area under an evaluation unit of 150 m×150 m grid. The results showed that sea-land hydrological connectivity gradually decreased from sea to land, with different decreasing rates. The spatial differentiation of water salinity in the study area was substantial, with certain impacts on the change rate of hydrological connectivity. The sea-land hydrological connectivity was divided into four grades, which was excellent, good, medium, and poor. The areas under excellent and good grades were mainly distributed in offshore areas, with saltwater aquaculture ponds and farmland as the main land use types. The regions with moderate and poor land use were mainly distributed in inland areas, with freshwater aquaculture ponds and farmland as the land use types. The hydrological process of coastal wetlands was complex. Quantitative coastal wetland hydrological connectivity could provide reference for coastal wetland status assessment and wetland restoration.