Recharge processes and groundwater evolution of multiple aquifers, Beijing, China

Abstract

A geological and hydrogeological survey was performed in the upper alluvial and proluvial fan and the northern mountain area of the Chaobai River in Beijing. Samples of local precipitation, surface water and groundwater (including spring discharges, groundwater from the fractured bedrock, and shallow and deep groundwater of the alluvium) were collected and analysed to assemble hydrochemical and isotopic data. Q-mode hierarchical cluster analysis (HCA) was used to classify the groundwater samples from multiple aquifers into objective groups. Two groups and six subgroups with distinct groundwater recharge sources, flowpath histories and geochemical evolution histories were identified. Inverse geochemical modelling was adopted to study the deep groundwater chemical evolution. Hydrochemical data and isotopic data on 2 H, 3 H and 18 O were used to evaluate groundwater recharge, flowpath histories and geochemical evolution, and 87 Sr was used to provide further insight into groundwater recharge sources and flow directions. It was found that particularly in areas of groundwater cones of depression, the deep alluvial groundwater may be partly derived from the groundwater of the underlying fractured bedrock. The phreatic, or unconfined, groundwater within the northern area of the alluvial and proluvial fan is sustained mainly by the lateral flow of groundwater from the piedmont regions and by recharge from surface water bodies such as the Miyun reservoir. The shallow alluvial groundwater within the central and southern areas of the alluvial and proluvial fan is recharged primarily by the local precipitation and agricultural irrigation. The deep alluvial groundwater within the central and southern areas of the fan is sustained chiefly by the flow of groundwater from the northern area of the fan or from the underlying fractured bedrock. Methodologies adopted in this work may be useful to future investigation of groundwater in multiple aquifer systems similar to this area.

Variations of Groundwater Dynamics in Alluvial Aquifers with Reclaimed Water Restoring the Overlying River, Beijing, China

“…The study area belongs to the piedmont alluvial area of the Chaobai River. The elevation of the mountainous area in upstream of the Chaobai River plain is generally from 400 m to 1500 m. Archean metamorphite, the middle-upper Proterozoic dolomite, Cretaceous rhyolite, Cambrian, and Ordovician limestone outcrop in the mountainous area [39]. The thickness of the unconsolidated Quaternary deposits ranges between 300 and 400 m in the study area [39].…”

Evaluating the impact of percolated reclaimed water from river-channel reservoir on groundwater using tracers in Beijing, Northern China

“…GW07 has the same isotopic composition and much lower 'deuterium excess' in both seasons in Group I, indicating steady source of groundwater recharge from highly evaporated water. In addition, GW07, as located up hydraulic gradient of the reclaimed water reservoir, has a similar isotopic composition to Miyun Reservoir (− 7.1‰ of δ 18 O and − 51‰ of δD) (Wu et al 2012) and therefore is recharged mainly by the piedmont surface runoff coming from the occasional discharge of the reservoir. The change of isotopes and TDS are quite limited between the dry and wet seasons for the three deep wells (GW03, GW12 and GW13) as these wells are located in a confined sand and gravel aquifer with a depth greater than 120 m. Little changes are due to the depth of these boreholes which smooth the changes.…”

“…4). The isotopic and hydrochemical constituents of the deep groundwater (GW03, GW12 and GW13) indicate that the groundwater comes from different recharge sources such as the metamorphic bedrock aquifer, the seepage of Minyun reservoir and local precipitation infiltration (Wu et al 2012).…”

Award-winning paper in 2012

“…The Robert Alfred Carr Prize, presented for the best paper published in Water Management, was awarded to Wu et al (2012).…”