Study on the Morphological Evolution of the Oujiang Estuary, China, in the 21st Century

Based on four years of spatially synchronous topographic data the Oujiang Estuary from 2002 to 2019, variations and physical mechanisms estuarine evolution driven by natural conditions human activities since beginning this century were analyzed. The results show that has changed dramatically in past 20 years. From net sediment erosion estuary was 163.44 million m3, average bed elevation river-dominated section (RDS), transition (TS) tide-dominated (TDS) decreased 4.61 m, 1.30 m 2.14 respectively. In addition, pattern shoal channel had changed, river facies coefficient (width–depth ratio) 16–64%. is mainly caused (such as sand mining, reclamation). Sand mining direct cause riverbed undercutting, large undercutting terrain causes increase tidal power further scouring. last years, annual range increased 0.19–1.14 flood discharge about 17–80%, with an value 58%. impact development significantly. Apart reclamation projects such Wenzhou outside mouth also local velocity current increase, which aggravates scouring trend sections downstream. silting changes are result adjustment system response strong intervention activities.