Intensified salinity intrusion in coastal aquifers due to groundwater overextraction: a case study in the Mekong Delta, Vietnam
Intensified salinity intrusion in coastal aquifers due to groundwater overextraction: a case study in the Mekong Delta, Vietnam
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DOI：
10.1007/s11356-021-16282-3
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发表时间：
2021-09
影响因子：
5.8
通讯作者：
D. Tran;M. Tsujimura;H. Pham;Tam V. Nguyen;L. Ho;Phu Le Vo;Khai Quang Ha;Thanh Duc Dang;Doan Van Binh;Quang‐Van Doan
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作者：
D. Tran;M. Tsujimura;H. Pham;Tam V. Nguyen;L. Ho;Phu Le Vo;Khai Quang Ha;Thanh Duc Dang;Doan Van Binh;Quang‐Van Doan
地下水盐碱化是世界范围内沿海含水层最严重的环境问题之一，导致地下水供应系统中的盐分超标。在内陆几公里处可以检测到地下水中的高盐度，这可能会增加沿海供水系统和人类健康问题的风险。本研究探讨地下水抽水的做法和区域地下水流动力学的影响，地下水流和盐度入侵在越南湄公河三角洲沿海含水层使用SEAWAT模型-变密度地下水流和溶质运移模型。该模型构建在三维（3D）和占多含水层，在邻近地区，抽水，和古盐度的地下水位的变化。模型校准进行了13年（2000年至2012年），验证进行了4年（2013年至2016年）。最佳校准模型用于开发未来14年（2017年至2030年）的预测模型。根据抽水率和区域地下水位，提出了六种未来情景。模拟结果表明，地下水开采活动和区域地下水流系统的变化强烈影响地下水位的下降和盐从上层到下层的运动。在今后14年中，随着地下水抽水能力的增加，预计高盐度（>2.0克/升）将向下扩展到150米深，并向周围地区扩展到2000米。随着地下水开采量的减少，水位也略有恢复。为了恢复地下水水位和保护淡水蓄水层不受地下水中古盐份扩大的影响，有必要在地方和区域范围内降低抽水率。
Groundwater salinization is one of the most severe environmental problems in coastal aquifers worldwide, causing exceeding salinity in groundwater supply systems for many purposes. High salinity concentration in groundwater can be detected several kilometers inland and may result in an increased risk for coastal water supply systems and human health problems. This study investigates the impacts of groundwater pumping practices and regional groundwater flow dynamics on groundwater flow and salinity intrusion in the coastal aquifers of the Vietnamese Mekong Delta using the SEAWAT model—a variable-density groundwater flow and solute transport model. The model was constructed in three dimensions (3D) and accounted for multi-aquifers, variation of groundwater levels in neighboring areas, pumping, and paleo-salinity. Model calibration was carried for 13 years (2000 to 2012), and validation was conducted for 4 years (2013 to 2016). The best-calibrated model was used to develop prediction models for the next 14 years (2017 to 2030). Six future scenarios were introduced based on pumping rates and regional groundwater levels. Modeling results revealed that groundwater pumping activities and variation of regional groundwater flow systems strongly influence groundwater level depletion and saline movement from upper layers to lower layers. High salinity (>2.0 g/L) was expected to expand downward up to 150 m in depth and 2000 m toward surrounding areas in the next 14 years under increasing groundwater pumping capacity. A slight recovery in water level was also observed with decreasing groundwater exploitation. The reduction in the pumping rate from both local and regional scales will be necessary to recover groundwater levels and protect fresh aquifers from expanding paleo-saline in groundwater.