Evidence of layered piezometry system within the chalk aquifer in parts of southeast England

In regional groundwater management studies, the Chalk aquifer is often considered a single, homogeneous, isotropic groundwater system, even though it has been subdivided into several lithostratigraphic units. Low permeability layers, including marl bands and hardgrounds, extend on a regional scale and define different layers within the Chalk. Four case studies in different locations of the Chalk aquifer of southeast England are presented: 1) A multi-level observation borehole in the Upper Colne catchment in Hertfordshire, 2) Different water levels in shallow and deep boreholes in the River Ver catchment, 3) Artesian conditions and rises in groundwater level during drilling in the Chiltern Hills and 4) Groundwater level separation in a public water supply borehole in Kent. The evidence clearly shows a layered system in the Chalk and vertical hydraulic discontinuity within the studied sequences. The current conceptual model of the Chalk aquifer should be enhanced to include the updated understanding and used to update the existing numerical groundwater models. This will in turn increase the confidence in the current decision-support tools for environmental sustainability and water resources management in the Chalk aquifer.