Effects of Marine Overwash for Atoll Aquifers: Environmental and Human Factors
Effects of Marine Overwash for Atoll Aquifers: Environmental and Human Factors
复制标题
海洋过度冲刷对环礁含水层的影响：环境和人为因素
作者：
R. Bailey;J. Jenson
环礁岛被海洋过度冲刷淹没，对淡水构成严重威胁，而在人工蓄水或其他水资源基础设施枯竭或遭到破坏后，淡水可成为一种重要的紧急水资源。与干旱不同，干旱会慢慢耗尽水资源，而且往往可以及时预测，而过度冲刷可能会在没有任何警告的情况下发生，并可能破坏雨水集蓄和地下水储备。在这项研究中，一个基于SUTRA的模型被应用于估计地下水污染的过洗和随后恢复的新鲜地下水是如何受到地质因素（含水层水力传导性，分散性，和存在或不存在的珊瑚礁平板），事件的季节性时间（湿与干），并存在手挖威尔斯井穿透珊瑚礁平板的影响。将西太平洋地区的实际潮汐和降雨数据应用于具有西太平洋特性和条件的假设岛屿的模拟30个月恢复期。对于所有情况，结果表明，需要12至16个月才能实现60%的淡水恢复。然而，将有用量的地下水恢复到手挖威尔斯井典型深度的可接受盐浓度所需的时间仅为3至6个月。特别令人感兴趣的是珊瑚礁平板的影响，它作为渗透海水的屏障，从而在过洗事件和恢复过程中保留了一袋封闭的淡水，如果手头有必要的工具和设备，这可能是可以利用的。
Inundation of atoll islands by marine overwash is a serious threat to fresh groundwater, which can be a critical emergency water resource after artificial storage or other water resource infrastructure has been exhausted or destroyed. In contrast to drought, which slowly exhausts water supplies and often can be forecasted in time, overwash can occur with little warning and can ruin both rain catchment storage and groundwater reserves. In this study, a SUTRA‐based model is applied to estimate how groundwater contamination by overwash and subsequent recovery of fresh groundwater are influenced by geologic factors (aquifer hydraulic conductivity, dispersivity, and the presence or absence of a reef flat plate), the seasonal timing of the event (wet vs. dry), and the presence of hand‐dug wells that penetrate the reef flat plate. Actual tidal and rainfall data from regions in the western Pacific are applied to simulated 30‐month recovery periods for hypothetical islands with properties and conditions characteristic of the western Pacific. For all scenarios, results indicate that 12 to 16 months are required to achieve 60% recovery of fresh groundwater. However, the time required to restore useful quantities of groundwater to acceptable salt concentration at depths typical of hand‐dug wells is only 3 to 6 months. Of particular interest is the influence of the reef flat plate, which acts as a barrier to infiltrating seawater, thus preserving a pocket of confined freshwater during an overwash event and the recovery, which could probably be utilized if the necessary tools and equipment are on hand.