Influence of Estuarine Topography on Longitudinal Dispersion

河口地形对纵向扩散的影响

• 批准号: 0452054
• 负责人: Wayne Geyer
• 金额: --
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-03-01 至 2009-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0452054&HistoricalAwards=false
• 关键词: Influence; Estuarine; Topography; Longitudinal; Dispersion

ABSTRACTOCE-0452054The longitudinal dispersion rate sets the residence time of waterborne material in estuaries, controls how far the salinity intrusion advances up-river and determines the response time of an estuary to changes in forcing conditions. The dispersion rate can vary by more than two orders of magnitude in different estuaries and can vary by more than an order of magnitude in a particular estuary depending on the forcing conditions. Furthermore, the mechanisms that set the dispersion rate can change with location within an estuary depending on the local geometry and the proximity to the mouth. In spite of its importance, the physics which govern estuarine dispersion remain poorly understood. This project will address the mechanisms of dispersion with a study of three estuaries with a wide range of forcing conditions and geometries. The research will include new measurements at two sites (the Merrimack and the North Rivers) and analysis of existing data and model results from the Hudson River. The field measurements will consist of 45 day deployments of cross-channel and longitudinal instrument arrays to quantify the salt flux and longitudinal salinity structure, and detailed shipboard measurements to provide high-resolution flux estimates and document the overall spatial structure of the current and salinity fields. Similar data sets from Hudson River, and a numerical model will be used to determine the mechanisms that control the dispersion rate over a broad range of forcing conditions and at different sections of the river with distinct channel morphology. This multi-system approach will allow the analysis to encompass some of the diversity of estuarine environments, allowing these results to be generalized to many estuaries worldwide. Broader impacts: Dispersion rate is the most important physical quantity affecting estuarine and coastal water quality. With increasing societal pressure on these waterways (e.g., nutrient loading and other non-point-source discharges) and higher expectations for environmental quality, understanding of the dispersion processes is an increasing priority. Better understanding will lead to better prediction and management.

纵向扩散率决定了水体物质在河口的停留时间，控制了盐度入侵向上游推进的程度，并决定了河口对强迫条件变化的响应时间。根据不同的强迫条件，扩散速率在不同的河口可以变化两个数量级以上，在特定的河口可以变化一个数量级以上。此外，设置扩散速率的机制可以随着河口内的位置而变化，这取决于当地的几何形状和与河口的接近程度。尽管它很重要，但控制河口色散的物理学仍然知之甚少。该项目将通过对三个具有广泛强迫条件和几何形状的河口的研究来解决分散机制。这项研究将包括在两个地点（梅里马克河和北河）进行新的测量，并分析来自哈德逊河的现有数据和模型结果。现场测量将包括为期45天的跨通道和纵向仪器阵列部署，以量化盐通量和纵向盐度结构，以及详细的船上测量，以提供高分辨率通量估算并记录当前和盐度场的整体空间结构。将使用来自哈德逊河的类似数据集和一个数值模型来确定在广泛的强迫条件下和在具有不同河道形态的河流不同路段控制扩散率的机制。这种多系统方法将允许分析包括一些河口环境的多样性，允许这些结果推广到世界各地的许多河口。更广泛的影响：扩散速率是影响河口及沿岸水质的最重要物理量。随着社会对这些水道的压力越来越大（例如，营养物负荷和其他非点源排放）以及对环境质量的更高期望，对扩散过程的理解日益成为一个优先事项。更好的理解将导致更好的预测和管理。