滨海盆地变密度地下水流与溶质运移三维耦合数值模型研究

Study on three-dimensional numerical model of variable-density groundwater flow and solute transport in the coastal basin

针对滨海含水层的复杂性,以北部湾经济区合浦盆地地下水资源应急潜力评价为例,通过概化出合浦盆地水文地质概念模型的基础上,采用SEAWAT模块建立了合浦盆地变密度地下水流与溶质运移三维耦合数值模型。在对模型进行识别、验证的基础上,假设2025年10月出现极端干旱,在保证不发生海水入侵的条件下,获得了度过整个枯水期各水源地地下水资源应急潜力。结果表明:合浦盆地地下水资源应急潜力为83.13万m 3/d,集中开采区中心地下水水头下降3~8 m,2 a后水位基本恢复;集中开采区降落漏斗远离海岸线,不受到海水入侵的影响。该方法将滨海水源地地下水应急供水预测和盆地的水文地质结构及当地发展规划紧密结合起来,为合浦盆地地下水资源的合理开发利用和应急能力建设提供了可靠依据。

Aiming at the complexity of the coastal aquifer,the three-dimensional coupling numerical model of variable density groundwater flow and solute transport simulation is applied with the SEAWAT module in the potentiality assessment of emergency groundwater resource of Hepu Basin in Beibu Gulf Economic Zone,and then three-dimensional numerical model is set up.After identification and verification,the model is used to predict the water supply capability of coastal aquifer under an extreme drought event in October,2025,assuring that the seawater intrusion will not occur.It is concluded that the maximum water supply can reach 83.13×104 m 3/d,the groundwater head of central groundwater in centralized mining area drops by 3~8 m,and the water level will basically recover after 2 years.Moreover,the cone of depression is far from the coastline and the exploited aquifer will not be affected by the seawater intrusion.The method provides a reliable basis for the rational exploitation and emergency capacity building of groundwater resources in Hepu Basin,which combines the prediction of emergency groundwater supply in coastal waters with the hydrogeological structure of the basin and local development planning.