Evaluation of Groundwater Flow Model for Arsenic Mobilization in the Datong Basin

To advance understanding of hydrological influences on arsenic transportation within groundwater of the Datong Basin, a transient 3D groundwater flow model was implemented based on data monitored at an experimental site (Shanyin experimental plot). The modeling results indicate that irrigation diminishes the groundwater head and accelerates the water exchange among different formations. Vertical water exchange occurs frequently among silt (L1, L2, L3, L4), clay1 (L5), and sand 1 (L6), but does not occur in clay 2 (L7), sand 2 (L8), clay 3 (L9), and sand 3 (L10). It is noted that horizontal groundwater exchange is prevailing and occupies the leading position in the saturated zone. The modeling results also show that the vertical movement of recharge water from the ground surface towards the deep aquifer induces a downward movement of arsenic, and the frequency of groundwater exchange greatly promotes the horizontal migration of arsenic in the aquifer.