Influence of Estuarine Topography on Longitudinal Dispersion

纵向扩散率确定了河口中水性物质的停留时间，控制了盐度入侵向上游推进的距离，并确定了河口对强迫条件变化的响应时间。 在不同的河口，分散率可以变化超过两个数量级，并可以变化超过一个数量级，在一个特定的河口，这取决于强迫条件。 此外，设置分散率的机制可以根据当地的几何形状和接近口的河口内的位置而改变。 尽管它的重要性，物理支配河口扩散仍然知之甚少。 该项目将通过对具有各种强迫条件和几何形状的三个河口的研究来解决扩散的机制。 该研究将包括在两个地点（梅里马克和北河）的新测量，以及对哈德逊河现有数据和模型结果的分析。 实地测量将包括为期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计并记录海流和盐度场的总体空间结构。 类似的数据集从哈德逊河，和一个数值模型将被用来确定的机制，控制分散率在一个广泛的强迫条件下，在不同的部分，不同的河道形态。 这种多系统的方法将允许分析，包括一些河口环境的多样性，使这些结果被推广到世界各地的许多河口。 更广泛的影响：扩散率是影响河口和沿海水质的最重要物理量。 随着对这些水道的社会压力的增加（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，因此，了解扩散过程日益成为一个优先事项。 更好的理解将带来更好的预测和管理。

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.