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Investigation of rising nitrate concentrations in groundwater in the Eden Valley, Cumbria. 3, saturated zone studies

Butcher, A.; Lawrence, A.; Gallagher, A.; Burke, S.; Ingram, J.; Merrin, P.. 2008 Investigation of rising nitrate concentrations in groundwater in the Eden Valley, Cumbria. 3, saturated zone studies. Nottingham, UK, British Geological Survey, 72pp. (OR/08/024) (Unpublished)

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Abstract/Summary

This component Work Package of the Eden Valley Project was undertaken with the objective of determining the hydrogeological regime and hydrochemical stratification in selected boreholes. The subsequent aim is to apply this to better understand timescales for water movement through the saturated zone along a transect ending near to the River Eden where the Permo-Triassic sandstone aquifer is exposed or underlies thin superficial deposits. A previous report in this series confirmed rising nitrate trends in groundwater in the study area, and suggested that with continued land use practices and with no evidence of denitrification, that this trend would continue. Another concluded that the average recharge rate is probably in the range 425-470 mm/y and the rate of water movement through the unsaturated zone is c. 3.5-3.85 m/y. Based on this estimate of water movement in the unsaturated zone, the travel time for recharge to migrate from the soil to the water table (or the delay imposed by the unsaturated zone) over most of the area where the sandstone is free of superficial deposits in the Eden Valley is c. 14 years. However if the higher fells are not considered - closer to 10 years. Given the inherent uncertainties and limitations associated with the various methods for determining the hydrogeological regime in a boreholem, methods proposed were: (i) to date the pore water profile within the saturated zone using CFC and SF6 tracers (ii) to determine the variation of aquifer properties with depth, for the matrix (using laboratory techniques) and the aquifer (using field pumping techniques). (iii) To use groundwater models to estimate groundwater travel times in the saturated zones (this part of the project has not yet been funded). A transect approach was adopted using existing boreholes to the east of Penrith to the Eden floodplain and addressing gaps with infill drilling. Despite early promise other boreholes (on a ‘southern’ transect) were discounted due to inaccessibility or unsuitable construction. A c. 4km transect from the east of Penrith in a north-western direction to the floodplain of the River Eden was selected starting at previously drilled project borehole.

Item Type: Publication - Report (UNSPECIFIED)
Programmes: BGS Programmes 2008 > Groundwater resources
Funders/Sponsors: NERC, Environment Agency
Additional Information. Not used in RCUK Gateway to Research.: This item has been internally reviewed but not externally peer-reviewed
Additional Keywords: GroundwaterBGS, Groundwater, Nitrate pollution
Date made live: 07 Feb 2014 15:03 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/504798

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