Analysis of the Influence of Tidal Creek Dredging on Tidal Flat Hydrodynamics

In order to analyze the influence of tidal creek dredging on tidal flat hydrodynamics, a simulation analysis of hydrodynamics and water quality point transport in tidal flat area is carried out based on unstructured numerical model. The results show that after dredging the flow velocity in the tidal creek increases significantly during the high tide, whereas at the north side of the tidal flat the flow velocity decreases slightly, with a variation range being about 50%. The water level in the tidal creek changes rapidly during the high tide and the flow speed of the rising tide is greater than that of the falling tide. Affected by the water body returning from the tidal flat to the creek, the water returning time becomes longer during the falling tide. As a result, the ebb duration is over two times longer than the high tide duration. During the high tide the flow velocity in the tidal creek shows a unimodal distribution. In the period of falling tide, however, the flow velocity in the tidal creek shows a bimodal distribution, of which the first peak is caused by the dropping of water level in the whole tidal flat and the second one is induced by the water body returning from the tidal flat to the creek. The tidal creek is the main channel of water-body transportation. Tidal creek dredging is beneficial to increasing the tidal-holding capacity, reducing the direct floodplain velocity from the open sea, decreasing the retained water on the surface of the tidal flat and enhancing the flow speed of the water returning from the flat to the creek at the end of the falling tide. After the tidal creek dredging the number of the water quality point entering the tidal flat has increased by one times, of which parts of the water quality points run through the whole tidal flat, thus improving the water exchange process between the tidal flat and the open sea.