Assessing the Driving Forces of Submarine Groundwater Discharge

海底地下水排放（SGD）是一个重要的，但很大程度上是未量化的营养物质和其他溶解成分从陆地到沿海海洋的途径。沿海海洋学家和水文学家已经表明，只要有正水头的含水层在水力上与地表水体相连，就会发生淡水通过沉积物缓慢而持续的渗漏。现在人们认识到，相当数量的海水还通过沿海含水层系统进行再循环，淡水和盐水的输入为沿海沃茨提供了营养物质和其他溶解固体。然而，驱动过程的相对重要性和咸水流与淡水排放耦合的程度仍然没有得到很好的理解，缺乏预测能力。 出于这个原因，佛罗里达州立大学的研究人员将调查推动新鲜和含盐地下水排放的力量。 由于陆地（水力梯度，季节性补给周期）和海洋（波浪设置，潮汐泵送，水位差）的力量驱动地下流体流过沿海含水层和近岸沉积物，这个科学家团队将通过跨学科的方法来研究这些过程。从两端（陆地和海洋）以及两个学科（水文学和海洋学）解决SGD问题至关重要，因为驱动力在时间和空间上重叠，并且通过沿海沉积物测量的合成流体流动通常是复合强迫的结果。 该项目将通过长期测量（即，同位素示踪剂、渗透仪）、水文/地球物理调查和数值模拟。其目标是开发一个长期的数据集的所有参数是相关的SGD及其驱动力。 由于许多SGD驱动程序已经知道的时间变化，频率的参数和随后的SGD响应将被测量，以deconvolute的影响力。在更广泛的影响，这项研究将显着推进我们的理解的机制控制SGD。 提议在该地点沿海开发之前开展这项工作将提供一个基准，以便今后评估商业/住宅开发对沿海含水层的影响。 为了向沿海地区管理人员传播关于可持续发展及其影响的信息，将在项目的第三年举办一个讲习班。 研究生和本科生将参与该项目的实地和实验室研究。

ABSTRACTOCE-0520723Submarine groundwater discharge (SGD) represents an important, yet largely unquantified pathway for nutrients and other dissolved constituents from land to the coastal ocean. Coastal oceanographers and hydrologists have shown that slow yet persistent seepage of fresh groundwater through sediments occurs wherever an aquifer with a positive head is hydraulically connected to a surface water body. It is now recognized that a considerable amount of seawater is also recirculated through coastal aquifer systems and that both fresh and saline water inputs contribute nutrients and other dissolved solids to coastal waters. However, the relative importance of the driving processes and the extent to which saline water flow is coupled to fresh water discharges is still not well understood and the predictive capabilities are lacking. For this reason, researchers at Florida State University will investigate the forces that drive both fresh and saline groundwater discharges. Since both terrestrial (hydraulic gradient, seasonal recharge cycle) and marine (wave setup, tidal pumping, water level differences) forces drive subsurface fluid flows through coastal aquifers and nearshore sediments, this team of scientists will examine these processes via a cross-disciplinary approach. It is critical to tackle the problem of SGD from both ends (terrestrial and marine), and from both disciplines (hydrology and oceanography) because driving forces overlap in time and space and the resultant fluid flow measured through coastal sediments is often a result of composite forcing. The project will separate and evaluate these forcing functions by a combination of long-term measurements (i.e., isotopic tracers, seepage meters), hydrological/geophysical investigations, and numerical modeling. The goal is to develop a long-term data set on all parameters that are relevant to SGD and its driving forces. Since many SGD drivers have known temporal variations, the frequency of the parameters and the ensuing SGD responses will be measured to deconvolute the influence of the forces.In terms of broader impacts, this study will significantly advance our understanding of the mechanisms controlling SGD. Proposing to carry out the work prior to coastal development at the site will provide a baseline from which to assess the impact of commercial/residential development on coastal aquifers in the future. To disseminate information to coastal zone manager on SGD and its implications, a workshop will be held during the third year of the project. Graduate and undergraduate students will be involved in the field and laboratory studies of the project.