ABSTRACT
ABSTRACT: This paper reviews the data available on the range, distribution and variation in bulk hydraulic conductivity (k) of the Carnmenellis granite outcrop in SW England based on information drawn from a number of studies and sources. It is suggested that the granite aquifer can be characterised by four vertically distributed zones: an uppermost extremely weathered intergranular flow zone of very high k, up to 2 to 3 m thick; a high permeability upper zone, 30 to 100 m deep with k of around 105m/s and 106m/s; a moderately permeable middle zone extending to a few hundred metres in depth and exhibiting k in the region of 107 to 109m/s; beneath this the granite may be considered effectively impermeable, with k of around 109 and 101 0m/s, though water flow at depth can still be considerable within major discontinuities, providing local zones with k of 105m/s or more.
