The 4th Estuary Day Workshop was held from October 13-15 by Hohai University, Jiangsu Society for Oceanology and Limnology, and Jiangsu Key Laboratory of Coast Ocean Resources Development and Environment Security, More than 30 experts from Delft University of Technology, Deltares, UNESCO-IHE, University of Florida, USGS, HR Wallingford, University of Southampton, University of Auckland, University of Padova, National University of Singapore, State Key Laboratory of Estuarine and Coastal Research, Nanjing University, Nanjing Hydraulic Research Institute participated. Frontier research on morphodynamic equilibrium in tidal environment and expected research achievement were warmly discussed.