Collaborative Research: Oligohaline dispersion: transport processes at the estuary-tidal river transition

合作研究：寡盐分散：河口-潮汐河过渡过程中的传输过程

• 批准号: 2318998
• 负责人: Robert Chant
• 金额: $ 58.63万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2318998&HistoricalAwards=false
• 关键词: Collaborative; Research; Oligohaline; dispersion; transport

Transport processes controlling the salinity distribution in an estuary vary dynamically with the river discharge, tides, and meteorological events. Most of our understanding of the transport processes is based on studies of the central reach of estuaries. The upper reach near the landward limit of the salt intrusion, has distinct physical characteristics that make transport processes different from the central reach. This project will combine in-situ and shipboard observations, dye release studies, and realistic high-resolution modeling to quantify tidal dispersion in the upper reach of the Delaware River estuary. Analysis of the observations and modeling will be closely linked through direct comparisons, and together they will be used to quantify dispersion rates and identify the mechanisms. Bathymetric features like channel constrictions and bends as well as anthropogenic modifications like piers and dredged channels are expected to be particularly important to creating salinity and velocity anomalies that lead to net landward transport. The Delaware is representative of many estuaries around the world where water supplies drawn from tidal rivers are increasingly threatened by landward shifts in the oligohaline reach with sea level rise, changing precipitation, and dredging. Specifically, drinking water intakes for the Philadelphia Water District (PWD) are located just upstream of the study region, and the Delaware River Basin Commission (DRBC) controls river flow conditions to regulate the salt intrusion and protect the water supply for millions. This project will build on established relationships between the PIs and colleagues at both PWD and DRBC to identify knowledge gaps and link study findings to management decisions. The PIs will also contribute to a series of workshops bringing together scientists and water resources managers to assess threats to water supplies by salt intrusion globally. The project will support a graduate student at Rutgers who will be involved in all aspects of the study, including observations, modeling, and outreach.The oligohaline reach (0.5-5 psu) is an important transition zone for many ecological and biogeochemical processes, and yet few studies have examined the physical mechanisms of transport. Several key characteristics distinguish the oligohaline from the central estuary. In the asymptote to freshwater, the along-estuary salinity gradient decreases and estuarine exchange flow weakens. Stratification also decreases, reducing the steady salt flux and increasing mixing, which reduces oscillatory shear dispersion. Channel narrowing affects lateral exchange and trapping, particularly in urbanized estuaries with shoreline modification. This project uses multiple, complementary approaches to quantify transport processes in this region. Observations during low river discharge will capture the spatial and temporal evolution of salinity with tidal and meteorological forcing, and dye releases will directly quantify dispersion at the scale of topographic features. Modeling will use a nested-grid approach to represent the bathymetric features driving dispersion, along with a novel analysis approach to isolate sources of non-local salt flux, as put forth by Dronkers and van de Kreeke (1986). A process-based understanding of transport in the oligohaline reach is critical to understanding how conditions there will evolve with climate change and continued development.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

控制河口中盐度分布的运输过程随着河流排放，潮汐和气象事件的动态变化。我们对运输过程的大多数理解都是基于对河口中心覆盖的研究。盐分侵入的陆上极限附近的上游具有独特的物理特征，使运输过程与中央覆盖率不同。该项目将结合原位和船上观测，染料释放研究和现实的高分辨率建模，以量化特拉华河河口上游的潮汐分散。对观测值和建模的分析将通过直接比较紧密相关，并将共同用于量化分散率并确定机制。预计，诸如通道收缩和弯曲以及诸如码头和疏and通道之类的人为修改之类的测深特征对于产生盐度和速度异常尤其重要。特拉华州是世界各地许多河口的代表，这些河口从潮汐河中抽出的水供应受到寡素河流的陆地变化的威胁，随着海平面的升高，降水量的变化和挖泥。具体而言，费城水区（PWD）的饮用水摄入量位于研究区的上游，特拉华河流域委员会（DRBC）控制着河流条件，以调节盐分的侵入并保护数百万的水供应。该项目将基于PIS和PWD和DRBC同事之间的既定关系，以确定知识差距并将研究结果与管理决策联系起来。 PI还将为一系列研讨会做出贡献，将科学家和水资源经理聚集在一起，以评估全球盐入侵对水供应的威胁。该项目将支持Rutgers的一名研究生，他们将参与研究的各个方面，包括观察，建模和外展。寡素覆盖范围（0.5-5 PSU）是许多生态和生物地球化学过程的重要过渡区，但很少有研究检查了运输的物理机制。几个关键特征将寡聚盐与中央河口区分开。在渐近到淡水的渐近线中，及格盐度梯度降低，河口交换流量减弱。分层还会减少，减少稳定的盐通量并增加混合，从而减少振荡性剪切分散体。频道狭窄会影响横向交换和捕获，特别是在海岸线修饰的城市化河口中。该项目使用多种补充方法来量化该地区的运输过程。低河流排放期间的观测将捕获盐度和气象强迫的空间和时间演变，而染料释放将直接在地形特征的规模下直接量化分散体。如Dronkers和van de Kreeke（1986）所述，建模将使用嵌套网格方法来表示驱动驱动分散体的测深特征，并采用新颖的分析方法来隔离非本地盐通量的源。基于过程对寡素覆盖的运输的理解对于了解随着气候变化和持续发展的条件将如何发展至关重要。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子和更广泛影响的评估评估来支持的。