HYDROSTRATIGRAPHY AND HYDROGEOCHEMISTRY OF THE VALE OF EDEN, CUMBRIA,UK

The nature and extent of the hydrostratigraphic units in the Vale of E den, Cumbria, has been established by an appraisal of existing lithost ratigraphical information. The Penrith and St Bees sandstones are the most important aquifiers; drift geology strongly influences recharge p rocesses. Regional recharge and discharge areas are apparent from exis ting piezometric data; the principal drain for groundwater in the Vale is the River Eden and its tributaries. The quality of groundwater in the Vale is generally good, and conforms to Ca-HCO3 facies. Local tren ds towards Ca-SO4 facies are found adjacent to the Eden Shales, but sa linities are not excessive. Nitrates are generally low, but in at leas t one shallow unconfined portion of the Penrith Sandstones, a rising t rend is discernible. The Penrith Sandstone waters are poorly buffered, and in some cases, pH is below 5.5. It is considered that this may lo cally be due to nitrification of ammoniacal fertilizers where the sand stone is unconfined. Groundwaters in the Vale are undersaturated with respect to the major carbonate minerals, but saturated with respect to silica (amorphous or as quartz) and massively super-saturated with re spect to hematite. This suggests that the characteristic cements of th e Penrith Sandstone may still be precipitating today. Priorities for f urther research include delineation of aquifer geometry and intensifie d hydrochemical monitoring.