A Simple Method for Estimating Mean Annual Groundwater Recharge for Drift-Free Areas of the Chalk and Permo-Triassic Sandstone Aquifers in the UK

At present, several methods for estimating groundwater recharge are in use in the UK, resulting in a range of estimates of groundwater recharge in any one area. However, there is a need for a robust national methodology with a firm scientific basis. As a first stage, a simple method has been developed to allow the rapid estimation of the mean annual groundwater recharge on drift-free areas of the major aquifers of England and Wales.
A simple soil-moisture model, with inputs of daily rainfall and potential evaporation, has been used to produce a series of nomographs. These can be used to estimate (a) mean annual groundwater recharge from data which are readily available, (b) annual values of rainfall, and (c) MORECS potential evaporation for grass. These estimates are aggregated to give the total for the area by including information on the land cover.