| A simple, practical model for estimating daily recharge - as
hydrologically effective rainfall (HER) - to the Chalk outcrop of southern
England is presented. Daily meteorological observations are the only data
requirements. The model was calibrated for a Chalk river, the Wey, in south
Dorset. Six different root constant thresholds were used to estimate daily
actual evapotranspiration (AET) rates for the river. The model was then used to
calculate HER using the six estimates of AET. Daily mean flow was simulated
using three different models: CAPTAIN, IHACRES and INCA. The six HER estimates
provided independent model inputs. HER calculated using a root constant of 200mm
proved suitable not only for the Wey, but also (via a validation exercise) for
other rivers on the Chalk of southern England for riverflow simulations as well
as the timing and magnitude of groundwater recharge. The results suggest that a
root constant of 200mm is optimal for the Chalk outcrop of southern England. The
model is particularly useful for studies where the application of more complex
methods of recharge estimation is impractical.
Keywords: Chalk aquifer, root constant, recharge, Hydrologically Effective Rainfall,
model, riverflow, CAPTAIN, IHACRES, INCA, River Wey |