长江口—杭州湾悬沙浓度的空间分布特征研究

Study of the spatial pattern of suspended sediment concentration in the Yangtze Estuary and Hangzhou Bay

本文通过搜集长江口—杭州湾水域23个测点,2011年洪、枯季大潮悬沙浓度数据,研究了该区域的悬沙浓度空间分布特征。结果表明:长江口—杭州湾的悬沙浓度存在明显的空间分布差异,北支大于南支,南支拦门沙区域大于南支上段,杭州湾区域则整体上大于长江口区域;长江口-杭州湾区域悬沙浓度自内向外整体呈先增大后减小的趋势。长江口—杭州湾泥沙虽基本来自长江径流输沙,但水体的悬沙浓度更多地受海洋动力作用控制,泥沙的再悬浮作用对水体含沙量的补充决定了该区域悬沙浓度的空间分布,故该区域的悬沙浓度主要表现为海洋性。

This study used suspended sediment concentration (SSC) data of a total of 23 stations to examine the spatial pattern of SSC in the Yangtze Estuary and Hangzhou Bay. These hourly data were collected during spring tides in both flood and dry seasons. Our results showed that there were significant spatial differences in this region. For example, the SSCs in the North Branch were much larger than that in the South Branch;the SSCs in the mouth bar area of the South Branch were larger than that in the upper reach;and the SSCs in Hangzhou Bay were larger than that in the Yangtze Estuary. It was also found that the SSCs increased first and then decreased longitudinally from the inner estuary to the open waters. Although these sediments mainly come from the Yangtze River, the SSCs in the Yangtze Estuary and Hangzhou Bay region are controlled by oceanic activity. The supplements from local bed sediments by re-suspension determine the spatial pattern of SSC in this region. Thus, the SSC levels in the Yangtze Estuary and Hangzhou Bay are primarily attributed to oceanic activity.