Study on material transport in Dingzi Bay based on the lagrangian method

Dingzi Bay is located in the eastern part of the Shandong Peninsula and is a typical semi-enclosed narrow bay. Affected by human activities such as land reclamation and pollutant discharge, the ecological environment quality has seriously deteriorated. To reveal the transport of pollutants in Dingzi Bay, this paper utilizes the unstructured Finite Volume Coastal Ocean Model (FVCOM) and a Lagrangian particle tracking model, combined with the Lagrangian Flow Networks (LFN) theory. By employing indicators such as indegree and betweenness from flud networks, the material aggregation areas, and key nodes of the Dingzi Bay were revealed. The results show that the main areas for material accumulation are the bay head, the northerncentral nearshore region, the cap areas, and the deep-water regions. Among these, the material retention rate in the sea area at the head of the bay reaches 95% within 25 hours. The betweenness centrality in the central deep-water area of the bay is relatively high, making it the primary channel for material diffusion.