Tidal rectification on drying estuarine sandbanks
Tidal rectification on drying estuarine sandbanks
复制标题
河口干沙洲潮汐整治
DOI：
10.2307/1352614
复制
发表时间：
1997
期刊：
影响因子：
--
通讯作者：
A. Al
中科院分区：
文献类型：
--
作者：
D. Bowers;A. Al
干涸的河口沙洲只经历高潮附近的潮汐循环。在部分前进的潮波中，这意味着沙洲上涨潮的持续时间将大于落潮的持续时间：这是一个潮汐矫正的过程。在本文中，我们提出的假设，这将导致洪水定向潮余流在干燥的沙洲。通过康威河口（北威尔士垂直混合良好的大潮河口）的观测和二维水动力模型来检验这一假设。观测数据包括验潮仪数据、潮汐循环船调查和固定流速计数据。数据显示，弱的洪水导向的剩余电流在干燥的沙洲和更强的退潮导向的残留物的渠道沿着两侧的沙洲。该模型再现的观测结果在附近的沙洲，并表明，潮汐整流机制产生的剩余环流在河口的一般模式，与洪水导向的流动在干燥地区和退潮导向的流动在渠道。洪水余差在河口附近最为显著，此处潮波性质最进步。这种机制的主要应用被认为是在推移质泥沙的运输。洪水导向的残留物将倾向于将沙洲的顶部向上游移动。
Drying estuarine sandbanks experience only that part of the tidal cycle around high water. In a partially progressive tidal wave, this means that the duration of the flood over the sandbank will be greater than that of the ebb: a process of tidal rectification. In this paper, we propose the hypothesis that this leads to flood-directed tidal residual currents over drying sandbanks. The hypothesis is tested by observation and a 2-D hydrodynamical model in the Conwy estuary, a vertically well-mixed macrotidal estuary in North Wales. The observations include tide gauge data, tidal cycle boat surveys, and fixed current meter data. The data show weak flood-directed residual currents over a drying sandbank and much stronger ebb-directed residuals in the channels along the sides of the sandbank. The model reproduces the observations in the vicinity of the sandbank and shows that the tidal rectification mechanism produces a general pattern of residual circulation in the estuary, with flood-directed flow in the drying areas and ebb-directed flow in the channels. The flood residuals are most marked near the estuary mouth where the tidal wave is most progressive in nature. The main application of this mechanism is believed to be in the transport of bedload sediment. The flood-directed residuals will tend to move the tops of the sandbanks upstream.