The Dynamics and Evolution of a Coastal Water-Table Aquifer Under a Regime of Slowly Rising Sea Level

海平面缓慢上升状态下沿海地下水位含水层的动态与演化

• 批准号: 9218972
• 负责人: Leonard Gardner
• 金额: $ 27.47万
• 依托单位: University of South Carolina at Columbia
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-05-01 至 1997-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9218972&HistoricalAwards=false
• 关键词: Dynamics; Evolution; Coastal; Water; Table

This project addresses the problem of the dynamics and evolution of the freshwater - saltwater interface in ground water along the forest - marsh boundary in South Carolina. The position and expression (i.e. clarity versus diffuseness) of this interface is governed by short-term forcings (diurnal tides, daily ET cycles and rain events), episodic storm surges and long-term sea level rise. Prediction of the fate of contaminants released on land and their impact on adjacent marshes depends on a clear and quantitative understanding of the movement of ground water at and near this interface. Because of the complex forcings and boundary conditions, presently available models for coastal aquifers are too simple to adequately simulate such systems. In addition, adequate field measurements of head and salinity are not available to test complex numerical models that might be used. As a remedy to this problem, the objectives of this project are to collect long-term measurements of head and salinity along transects across the forest-marsh boundary and to use the data to develop, calibrate and validate a numerical model of the system. A spatially dense network of piezometer along each transect will be equipped with recording pressure transducers (assembled in house) that will gather data on the effects of short-term forcing. Based on geomorphic and stratigraphic criteria and C-14 dating of tree roots found in high marsh soils, transects will be selected to represent stages in the conversion of a forested, pleistocene beach ridge terrain into a Holocene salt marsh under a regime of rising sea level. This will provide a unique opportunity to test our numerical model against truly long-term data. The results of this project could be used by regulatory agencies for environmental impact assessment and planning and by ecologists interested in interactions between forest and marsh ecosystems.

该项目解决了南卡罗来纳州森林-沼泽边界沿线地下水中淡水-咸水界面的动态和演化问题。 该界面的位置和表达（即清晰度与扩散度）受短期强迫（每日潮汐、每日ET周期和降雨事件）、间歇性风暴潮和长期海平面上升的控制。 对陆地上释放的污染物的命运及其对邻近沼泽的影响的预测取决于对该界面及其附近地下水运动的清晰和定量的了解。 由于复杂的强迫和边界条件，目前可用的沿海含水层模型过于简单，无法充分模拟此类系统。 此外，没有足够的水头和盐度现场测量来测试可能使用的复杂数值模型。 作为解决这一问题的方法，该项目的目标是收集沿森林沼泽边界横断面的水头和盐度的长期测量结果，并使用这些数据来开发、校准和验证系统的数值模型。 沿着每条横断面的空间密集的测压计网络将配备记录压力传感器（内部组装），用于收集有关短期强迫影响的数据。 根据地貌和地层标准以及在高沼泽土壤中发现的树根的 C-14 测年，将选择横断面来代表在海平面上升的情况下森林覆盖的更新世海滩山脊地形转变为全新世盐沼的阶段。 这将为根据真正的长期数据测试我们的数值模型提供一个独特的机会。 该项目的结果可供监管机构用于环境影响评估和规划，也可供对森林和沼泽生态系统之间相互作用感兴趣的生态学家使用。