The effects of the 1975–76 drought on groundwater and aquifers

Abstract

The drought of 1975–76 that affected not only the British Isles but extended to much of the continent of Europe, became severe only after the exceptionally dry winter of 1975/76 when within most of England and Wales negligible recharge to aquifers occurred. Thus by the spring of 1976 when seasonal underground storage should have been at its peak, aquifer storage was already at a very low level. Since, however, groundwater levels in aquifers are controlled by local and variable base level drainage conditions, the extent to which further falls in level could occur under natural unconfined conditions was limited so that by autumn 1976 in most places levels were lower than those previously recorded by only a few metres. Within confined aquifers having lower storativities, effects were usually more severe and falls in level below those previously recorded of more than 10 m occurred. Had it not been for the exception­ally wet winter of 1974/75 when recharge to aquifers was generally well above average, groundwater levels in the autumn of 1976 might have been considerably lower. The authors have been unable to discern any long-term adverse effects on British aquifers in which by the early spring of 1977 groundwater levels had, in almost every known case, recovered to higher than average levels except in areas with levels lowered previously by over-abstraction. No permanent ill effects on groundwater quality have so far become apparent.