The study looked at how the riverbed and silt build-up in the South Passage of the Yangtze Estuary have changed over time. By analyzing underwater data and project progress, researchers found that the upper part of the passage is eroding while the lower part is filling up. The mouth bar is getting shorter and the riverbed is rising. The volume of Jiangya'nansha Shoal is increasing, and it is extending downstream. The main reason for the silt build-up seems to be the natural deposition of the shoal.