No abstract

No abstract

No abstract

Tidal creek is an important natural carrier of hydrological connectivity in coastal wetlands, and an important channel for material exchange between sea and land. Based on the remote sensing image data from 1987 to 2020, the spatio-temporal divergence patterns of tidal creek network and its hydrological connectivity were revealed. The results showed that: (1) The morphology of tidal creeks was similar to the "tree-shaped" development, and the tidal creeks at all grades tended to be "short, fragmented and parallelized" during 1987-2020. and the number, density of the tidal creeks showed an increasing trend year by year. (2) The development degree of tidal creek networks showed a trend of gradually increasing from north to south, with the tidal creek development in areas II and V showing the good network development characteristics. (3) The spatial heterogeneity of hydrological connectivity levels of tidal creeks in the study area was obvious, which gradually increased from the north to south, with the best in the southern Area V and the worst in the northern Area I. The results of this study revealed the development process and evolution mechanism of the tidal creek networks in coastal wetlands.

Ditch networks play crucial roles in regulating water fluxes with their surroundings. The connectivity of ditches can have great impacts on nutrient migration and transformations. However, connectivity patterns related to ditch networks have rarely been studied, especially the relationships with water quality assessed through spatial analysis. This paper considered ditch connectivity and water quality indicators comprehensively, using spatial autocorrelation and geographically weighted regression (GWR) models, to analyze the impact of ditch connectivity on water quality from urban to rural gradients. The results suggested that water quality in rural areas and towns was better than in suburbs and transition zones, and the different areas exhibited variable spatial ditch connectivity. The Moran’s I index of the connectivity indicators showed the clustering state of spatial distribution, with ditch connectivity explaining 61.06% of changes in water quality. The circularity and network connectivity of the ditches had the most influence on water quality. However, the degree of influence varied with region. Circularity had the greatest impact on water quality in urban areas, and network connectivity had the greatest impact on water quality in township areas. Therefore, future water improvement projects, based on ditch optimization and management, need to consider the more related influencing factors and their spatial differences.