Sediment Budget of the Mouth Bar in the Yangtze Estuary Response to the Change of Marine Input Conditions: A Process-Based Model Approach

The transition of upstream or open sea conditions eventually leads to the change of sediment budget in estuaries and results in its evolution. In this paper, marine facies change for the Yangtze Estuary has been investigated based on statistics and harmonic analysis on the observed water-level time series at stations. The sea-level rise (SLR) rate and the main tidal constituent change were obtained for the estuary. Scenarios were designed to represent change of input conditions for the process-based model of the estuary. The net sediment budget of the mouth bar area in the estuary was calculated according to the cumulative flux through the predefined controlling cross-sections. The results reveal that (1) the SLR in the coming two decades results in sediment demand increase in the mouth bar area and restrains the seaward export sediment; (2) amplitude of the M-2 component increase slightly enhances seaward sediment export; and (3) the combination of SLR and M-2 increase responses for sediment demand increase in the mouth bar area, and 1.5% more sediment export to sea.