Estimating daily recharge to the Chalk aquifer of southern England – a simple methodology

摘要

A simple, practical model for estimating daily recharge - ashydrologically effective rainfall (HER) - to the Chalk outcrop of southernEngland is presented. Daily meteorological observations are the only datarequirements. The model was calibrated for a Chalk river, the Wey, in southDorset. Six different root constant thresholds were used to estimate dailyactual evapotranspiration (AET) rates for the river. The model was then used tocalculate HER using the six estimates of AET. Daily mean flow was simulatedusing three different models: CAPTAIN, IHACRES and INCA. The six HER estimatesprovided independent model inputs. HER calculated using a root constant of 200mmproved suitable not only for the Wey, but also (via a validation exercise) forother rivers on the Chalk of southern England for riverflow simulations as wellas the timing and magnitude of groundwater recharge. The results suggest that aroot constant of 200mm is optimal for the Chalk outcrop of southern England. Themodel is particularly useful for studies where the application of more complexmethods of recharge estimation is impractical. style="line-height: 20px;">Keywords: Chalk aquifer, root constant, recharge, Hydrologically Effective Rainfall, model, riverflow, CAPTAIN, IHACRES, INCA, River Wey