Synchronized biophysical measurements of an accretional-erosional transitional tidal marsh wetland in the central Jiangsu Coast, China

Tidal marsh wetlands provide essential and valuable services to human society and the wider interconnected marine and coastal environment. Understanding their intertwined biophysical processes and morphological evolution is crucial for developing effective management strategies to conserve and protect wetlands in the face of global change. The study area is an accretional-erosional transitional wetland on an open tidal coast, which is located in Doulong, Jiangsu Province, China. This study presents a dataset of seasonal synchronized biophysical measurements from September 2020 to July 2021, including morphological patterns, bed elevation, hydrodynamics, vegetation, and sediment characteristics. Observations show that synchronous physical and biological data can result in a more comprehensive and accurate understanding of the evolution of geomorphological units, reflecting the multi-factor interactions in tidal salt marsh systems. Two specific morphological patterns were observed: the alongshore expansion of saltmarsh patches, and the evolution of debris bands and unvegetated zones within saltmarshes. In the northern part of the study area, the seaward expansion of saltmarshes was characterized by rapid alongshore expansion (180 m in one year), followed by the connection of patches and merging with the marshland. In the context of this protruded-shoreline marsh, the strong alongshore currents were the essential conditions for the alongshore expansion. Moreover, results showed that debris bands and unvegetated zones have a significant impact on the evolution of salt marshes. Debris bands could result in a reduction of approximately 52% in vegetation biomass during summer and approximately 30% during other seasons. They were classified into three main categories according to their movement and composition: stable, movable and organic type. Unvegetated zones were classified into two categories based on their duration: persistent and transient type.