Collaborative Research: Exploring the linkages between Sea-Level Change, Sediment Transport and Geomorphology on Coastal Freshwater Water Sequestration

随着传统水源的枯竭，沿海大城市的发展对饮用水的需求日益增加。当地地下水开采的增加导致了更广泛的盐水入侵事件，新的地表水供应在政治上和经济上都变得难以获得。在过去的百万年里，随着海平面的上升和下降，海岸线向陆地和海洋方向移动，改变了淡水和咸水之间的界限，结果经常可以在近海找到淡水水库。如果没有其他水源，这些水可以为沿海地区提供重要的储备。该项目将查明新泽西州大陆架和孟加拉国近海三角洲地区海洋沉积物中埋藏的淡水的程度。这项研究将使用来自地球物理调查、沉积物沉积、地下水流动和溶质运输的数据，建立数学模型，模拟海平面上升时这些海底沉积物中淡水的积累。该项目还将对这些地区的地下水生产进行模拟，以评估在未来几十年内进入近海水库的可行性。该项目将评估在100万年或更长时间的地质时间尺度上，地貌学、沉积学、地球动力学和水文过程之间的相互作用如何影响沿海环境中陆地咸水和近海淡水的封存。这项研究将使用地球科学社区代码Landlab开发一个新模型，并将代码应用于两个具有不同当地海平面、气候、构造和沉积物运输机制的野外地点：新泽西州和孟加拉国。这些模型计算出的沉积物类型和盐度模式将与地震和电磁（EM）数据的新图像和现有图像进行比较，并与测量水的盐度和年龄的现有井样进行比较。将在孟加拉国进行电磁调查，以确定在这一活跃的三角洲环境中深水陆上盐水和淡水的分布。与最近从新泽西州近海收集的EM图像一起，这些数据将用于测试Landlab模型，以阐明控制沿海地区淡水和咸水就位的因素。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The growth of large coastal cities is putting increasing demand on supplies of potable water as traditional sources are depleted. Increased withdrawal of local groundwater has led to more widespread occurrences of salt-water intrusion and new surface-water supplies are becoming politically and economically difficult to access. As sea level rose and fell over the past million years, the shoreline moved landward and seaward, shifting the boundary between fresh water and salt water with the result that reservoirs of freshwater can often be found offshore. This water could provide a significant reserve for coastal areas if other sources are unavailable. This project will identify the extent of freshwater buried in marine sediments in the continental shelf of New Jersey and in the offshore delta region of Bangladesh. The research will use data from geophysical surveys, sediment deposition, groundwater flow, and solute transport, to develop mathematical models that simulate the accumulation of freshwater in these submarine deposits as sea level rose. The project will also construct simulations of groundwater production from these areas to assess the feasibility of accessing the offshore reservoirs within the next few decades.The project will assess how sequestration of onshore saltwater and offshore freshwater in coastal environments is influenced by interactions between geomorphic, sedimentological, geodynamic, and hydrologic processes over geologic time scales of one million years or more. The research will develop a new model using the Earth-science community code, Landlab, and apply the code at two field sites with vastly different local sea-level, climate, tectonic and sediment transport regimes: New Jersey and Bangladesh. Calculated sediment type and salinity patterns from these models will be compared to new and existing images from seismic and electromagnetic (EM) data, as well as to available well samples measuring salinity and age of the water. An EM survey will be carried out in Bangladesh to determine the distribution of deep onshore saltwater and freshwater in this active deltaic environment. Along with recently collected EM images from offshore New Jersey, these data will be used to test the Landlab model to elucidate the factors controlling the emplacement of fresh and saline groundwater in coastal regions.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.