SEDIMENT TRANSPORT IN A MOUNTAINOUS RIVER SUBAQUESOUS DELTA AND ITS RESPONSE TO MARINE SAND EXTRACTION: A CAST STUDY OF MINJIANG RIVER ESTUARY, SOUTHEAST CHINA COAST

When the terrestrial sediment enters the estuary through the river, it is affected by the topography, tide, wave and saltwater intrusion of the estuary and adjacent areas, and coarse sediments are enriched in this area, which makes it as an important area for marine sand extraction. Minjiang River, as a medium-sized mountainous river, has a large flux of water and sediment into the sea. Coarse sediments delivered by the Minjiang River are affected by tidal currents and topography after entering the estuary area, and converged mainly in the area east of Chuanshi Island, which makes this area as an important sea for marine sand resource enrichment. In recent years, the intensity of marine sand extraction activities is increasing. Marine sand extraction results in alterations of local topography and hydrodynamics, and further results in variations of local sediment transport process, resulting and then ultimately leads to changes in sediment composition and distribution patterns in marine sand extraction sites and surrounding areas.