Source protection zones in the Chalk (open version)

The aim of this report is to provide some general observations on the problem of delineating Source Protection Zones (SPZs) in the Chalk aquifer with particular consideration of the karstic nature of the Chalk. The SPZ delineation methodology for England is outlined in Environment Agency (2019), and the Source Protection Zone definitions are provided in Appendix 1. The high vulnerability of karst aquifers and the challenges of SPZ delineation in karst are highlighted in Environment Agency (2019); which details a bespoke manual approach to SPZ delineation for karst sources. This has been applied to sources where karst is obvious; principally in the Carboniferous Limestone. However, karst has not generally been considered for the majority of Chalk SPZs, which are mostly based on standard porous medium groundwater modelling approaches. Understanding of karst in the Chalk is rapidly evolving and in recent years considerable evidence of karst and rapid groundwater flow has become apparent, and the aim of this report is to consider the implications of this for source protection.