Dry years in south-east England since 1698

Abstract

THE recent drought and water shortage in England has re-emphasized the need for a more detailed knowledge and better understanding of the climate of the past. Without such information it is impossible to make meaningful statistical statements about the future occurrence of such extreme events. Many meteorological statements have been made about the severity and causes of the 1976 drought, mainly in the popular press, but also in the scientific literature¹. These statements have generally concerned precipitation; but data on precipitation alone are not necessarily good indicators of drought. In this paper we distinguish between three different kinds of drought—meteorological, hydrological and agricultural drought—noting that agricultural and hydrological drought conditions are determined, not only by rainfall, but also by evaporation and by the timing of rainfall events. Using both precipitation and evaporation data for Kew we derive a time series of soil moisture deficits which we believe gives a more rational measure of agricultural drought severity than can be obtained from precipitation data alone.