GroMoPo Metadata for Mekong Delta SEAWAT model

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.

地下水盐碱化是全球沿海含水层面临的最严重环境问题之一，导致众多用途的地下水供水系统盐分超标。地下水中的高盐浓度可检测至内陆数公里处，并可能增加沿海供水系统和人类健康问题的风险。本研究利用SEAWAT模型——一种变密度地下水流动和溶质运移模型，探讨了越南湄公河三角洲沿海含水层中地下水抽取实践和区域地下水流动动力学对地下水流动和盐分侵入的影响。该模型在三维（3D）空间构建，并考虑了多层含水层、相邻区域地下水位的变动、抽取和古盐度。模型校准持续了13年（2000年至2012年），验证期为4年（2013年至2016年）。最佳校准模型被用于开发未来14年（2017年至2030年）的预测模型。基于抽取速率和区域地下水位的六种未来情景被引入。建模结果表明，地下水抽取活动和区域地下水流动系统的变动强烈影响着地下水位的消耗和盐分从上层向下层迁移。预计在接下来的14年内，随着地下水抽取能力的增加，高盐度（>2.0 g/L）将向下扩展至150米深度，并向周边地区扩展2000米。随着地下水开采量的减少，也观察到水位略有恢复。从本地和区域尺度减少抽取速率将有必要恢复地下水位，并保护淡水含水层免受地下水古盐度扩张的影响。