Investigating the Impact of Seawater Intrusion on the Operation Cost of Groundwater Supply in Island Aquifers
Investigating the Impact of Seawater Intrusion on the Operation Cost of Groundwater Supply in Island Aquifers
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DOI：
10.1029/2023wr034798
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发表时间：
2023-09
影响因子：
5.4
通讯作者：
Weijiang Yu;Domenico Baù;Alex S. Mayer;L. Mancewicz;Mohammadali Geranmehr
中科院分区：
文献类型：
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作者：
Weijiang Yu;Domenico Baù;Alex S. Mayer;L. Mancewicz;Mohammadali Geranmehr
管理脆弱的岛屿淡水资源需要确定在地下水供应的财务成本与控制与含水层抽水相关的海水入侵(SWI)之间权衡的抽水战略。在这项工作中，通过在地下水管理问题的优化公式的背景下进行的敏感性分析来研究这些权衡，该问题旨在最小化与地下水开采和海水淡化处理相关的地下水供应运行成本，受水资源指数控制的约束，如井上的地下水位下降(∆S)、含水层中淡水体积的减少(∆FV)或含水层中的盐分质量增加(∆SM)。本研究的重点是圣萨尔瓦多岛(巴哈马)含水层的简化二维模型。抽水策略的特征是抽水系统到岸线的距离(WL)、抽提筛深(D)和总抽水速度(Q)，它们构成了优化问题的决策变量。我们考察了抽水策略对运行成本、∆S、∆FV和∆SM的影响。结果表明，增加D或减少WL会降低∆S、∆FV和∆SM，从而保持含水层的水文地质稳定性，但也会导致开采较咸的地下水，从而增加水处理需求，这对地下水总体供应成本有很大影响。从财务角度来看，在岛屿中心附近和浅层抽取地下水似乎是最方便的策略。然而，对优化约束的分析表明，抽水系统接近岛屿中心的策略往往会导致更严重的SWI，这突显了在地下水供应成本与SWI控制之间权衡的必要性。
Managing fragile island freshwater resources requires identifying pumping strategies that trade off the financial cost of groundwater supply against controlling the seawater intrusion (SWI) associated with aquifer pumping. In this work, these tradeoffs are investigated through a sensitivity analysis conducted in the context of an optimization formulation of the groundwater management problem, which aims at minimizing the groundwater supply operation cost associated with groundwater pumping and desalination treatment, subject to constraints on SWI control, as quantified by the water table drawdown over the well (∆s), the reduction in freshwater volume (∆FV) in the aquifer, or the salt mass increase (∆SM) in the aquifer. This study focuses on a simplified two‐dimensional model of the San Salvador Island aquifer (Bahamas). Pumping strategies are characterized by the distance of the pumping system from the shoreline (WL), the abstraction screen depth (D) and overall pumping rate (Q), constituting the decision variables of the optimization problem. We investigate the impacts of pumping strategies on the operation cost, ∆s, ∆FV and ∆SM. Findings indicate increasing D or decreasing WL reduces ∆s, ∆FV and ∆SM, thus preserving the aquifer hydrogeologic stability, but also leads to extracting saltier groundwater, thus increasing the water treatment requirements, which have a strong impact on the overall groundwater supply cost. From a financial perspective, groundwater abstraction near the island center and at shallow depths seems the most convenient strategy. However, the analysis of the optimization constraints reveals that strategies where the pumping system approaches the island center tend to cause more severe SWI, highlighting the need to trade off groundwater supply cost against SWI control.