Groundwater supplies to maritime and coastal defences in southern England: a story of risk and innovation

Abstract

AbstractThe viability of any fort or garrison depends on the availability of a reliable water supply. The source of choice is an underlying aquifer, reached by a secure on-site well or borehole. Unfortunately, at coastal and maritime sites, seawater intrusion can cause problems. In the late eighteenth century a deep well was sunk to supply the garrison at Sheerness, Kent, which successfully exploited sands beneath the London Clay. At Landguard Fort in Suffolk, a shallow gallery was designed to skim freshwater overlying saline water within loose sand and shingle. In the mid-nineteenth century, a network of forts was built to defend the Royal Dockyard at Portsmouth, which included some offshore forts on the Spithead shoals. Boreholes were drilled beneath these forts to abstract water from the Chalk thought to lie beneath. The Chalk proved to be at too great a depth, but the Bracklesham Group yielded a sustainable supply from <200 m. In carrying out these projects, military engineers sank wells and drilled speculative boreholes, taking financial risks, unacceptable in other parts of the public sector. They developed new technologies and their innovative ideas and discoveries led to an increased understanding of the distribution and use of groundwater.