地表水-地下水溶质运移耦合模拟研究——以某赤泥堆场项目地下水环境影响评价为例

Study of solute transport simulation considering the coupling of groundwater and surface water——A case study of an environmental impact assessment of a red mud disposal site on groundwater

目前的地下水环境影响评价中,地表水体常作为边界条件,不能体现地表水中的溶质运移过程。本文以某一赤泥堆场项目为例,采用GMS软件中的MT3D-USGS模块的SFT程序包建立河流—地下水—溶质耦合模型,预测氟化物在运营期14年运移扩散情况,评价污染物对区域地表水和地下水的影响。结果表明:(1)模拟流场能较真实的反应研究区的地表水和地下水流动特征;(2)在正常工况条件下,氟化物对地表水和地下水的影响较小;(3)在岩溶塌陷的情况下,氟化物仅2d就可运移至季节性河流,在运移2369d后最大超标距离已经达到河流,且氟化物有沿河流向下游运移的趋势,第14年氟化物沿河流运移到下游河流及沿岸地下水含水层,形成一个随河流扩散的污染晕。

In order to evaluate and predict the spatial-temporal variation of water quantity and water quality more accurately,a stream--groundwater-solute coupling model is established to predict the migration and diffusion between surface water and ground water.The Streamflow Transport Package(SFT)of MT3D-USGS is employed to couple with Streamflow Routing 2 Package(SFR2)of MODFLOW.The contaminate(fluoride)transport in groundwater is simulated in a red mud disposal site project as an example.The results show that:the simulated flow field can reflect the surface water and groundwater flow characteristics of the evaluation area more realistically;under normal working condition,the influence of fluoride on surface water and groundwater is less;In the case of abnormal working condition,fluoride can be transported to seasonal streams.After 2369 d,plume of fluoride would reach the stream,and fluoride could migrate downstream along the stream.In 14 years,there would be another plume in the aquifer at the downstream,indicating that the stream can accelerate the transport of contaminate as a preferential channel.