Development of an oil spill model adaptable to exposure and submergence conversion of tidal flats: A case study in the Changjiang Estuary

Through the application of the Water Pollution Emergency Response System (WPERS) in the Changjiang Estuary, it was found that tidal flats significantly affect the trajectory of an oil film, and the deposition of the oil film on tidal flats is remarkable. In this study, the Estuarine Oil Spill Model (EOSM) was developed to simulate the process of the oil film landing on tidal flats. The Lagrangian particle algorithm and oil fate experience algorithms were adopted. An algorithm for generating dynamic shorelines was also involved. Compared to the oil spill algorithm without wet-dry functionality, the spatial distribution of the oil film deposition simulated in the EOSM better matched the reanalysis data of the satellite remote sensing image. This indicated that the dynamic wet-dry switch phenomenon of tidal flats could be involved in the simulation of offshore oil spills to improve the accuracy of accident prediction and ecological loss assessment.On December 30th, 2012, a vessel carrying 400 tons of heavy oil sank in the Changjiang Estuary, China. The heavy oil leaked at around 4 am the next day. In this study, a new oil spill model was developed to simulate the process of an oil film landing on land and tidal flats. An algorithm for generating the dynamic shorelines in an oil spill simulation was adapted for the wet-dry switch of tidal flats. The landing distribution of the oil film in this new model was well matched to the satellite image for this accident. This indicated that the dynamic wet-dry switch phenomenon of tidal flats could be involved in the simulation of oil spills offshore, to improve the accuracy of accident prediction and ecological loss assessment. The research results could provide some new ideas for the development of offshore oil spill simulation technology.