关键词: 长江河口, 水位上升, 流场, 盐水入侵, 数值实验

Abstract: A semi-implicit estuarine, coastal, and ocean model (ECOM-si) was used to simulate and analyze the influence of a rise in water level on runoff, tidal and wind-driven currents, and on current and saltwater intrusion under the combined effects of various dynamic factors. In a scenario where the water level rises 30 cm in the Changjiang Estuary, numerical simulation results show that seaward runoff decreases due to augmentation of the river transection area; tidal currents decrease slightly with increases in water depth; the wind-driven current by northerly winds in the dry season is enhanced, which flow landward in the North Channel and seaward in the South Channel forming horizontal circulation; and the wind-driven current in the North Branch is strengthened. After the water level rise, saltwater intrusion in the North Branch is enhanced; salinity changes slightly in the middle reaches of the South Branch; the most distinct areas of saltwater intrusion enhancement are in the North Channel and North Passage, where the salinity rise is greater than 1 in neap tide and is somewhat reduced in spring tide; the salinity rise in the northern outlet of the North Channel reaches the maximum value observed in the entire estuary; and salinity on the shoal at the river mouth of the South Passage reduces because the water level rises and the nonlinear effect weakens. The water level rise, moreover, results in a salinity increase at the water intake of the three reservoirs (Qingcaosha, Chenhang, and Dongfengxisha) in the water source of the South Branch, which reduces water intake time and affects the safety of the water supply.

Key words: Changjiang Estuary, water level rise, current, saltwater intrusion, numerical experiment