Identifications of aquifer group classification by using environmental isotope and hydrogeochemistry method: a case study of Huabei plain, China

Aquifer group classification is a prerequisite for groundwater resources evaluation as well as groundwater utilization, which making an important effect on human being living and production activities. So far, lithology is the primary criteria in aquifer group classification, but the available and specific supporting ideas are still insufficient. Supposing that two aquifers separated by clay had hydraulic connection in multilayer aquifer systems, groundwater flow from top to bottom of aquifer would be impacted by the clay in chemistry and isotope characteristic and presents some kind of regulations. According to these regulations, aquifer group classification would be more reasonability, and groundwater resources assessment and pollution management would be more purposeful. This research analyzed the hydraulic connection of groundwater in different aquifer and salt movement in clay soil by using isotopic and chemical data. The results showed that electrical conductivity of groundwater in clay soil is influenced by the source of the groundwater, having a continuous trend with depth, and clay soil in certain depth presented the feature of impeding salt migration. Because of the semipermeable feature of clay soil, stable isotope composition of groundwater in different depth is affected by clay’s distribution. This pattern of isotope and hydrogeochemical composition would be a valuable reference for groundwater evaluation and aquifer group classification.