Abstract
The mean transit time (MTT) of a catchment is the average residence time of water from rainfall to river outflow at the foot of the catchment. As such, MTT has important water quality as well as resource implications. Many catchments worldwide have been measured for MTT using environmental isotopes, yet the Chalk, an important aquifer in NW Europe, has received little attention in this regard. The catchment of the River Lambourn in southern England has been intermittently studied since the 1960s using isotopic methods. A tritium peak measured in the river during the 1970s indicates an apparent MTT of {approx}15 years, but the thick unsaturated zone (average {approx}50 m) of the catchment suggests that the MTT should be much greater because of the average downward movement through the Chalk of {approx}1 m/a consistently indicated by tritium and other tracers. Recent work in the catchment using SF{sub 6} as a residence time indicator has given groundwater ages in the narrow range 11-18 yrs, apparently supporting the river tritium data but in conflict with the unsaturated zone data even allowing for a moderate proportion of rapid bypass flow. The MTT of the catchment remains unresolved for the time being. (author)
Darling, W. G.;
Gooddy, D. C.;
[1]
Barker, J. A.;
[2]
Robinson, M.
[3]
- British Geological Survey, Crowmarsh Gifford, Wallingford, Oxfordshire (United Kingdom)
- School of Civil Engineering and the Environment, University of Southampton, Southampton (United Kingdom)
- Centre for Ecology and Hydrology, Crowmarsh Gifford, Wallingford, Oxfordshire (United Kingdom)
Citation Formats
Darling, W. G., Gooddy, D. C., Barker, J. A., and Robinson, M.
Chalk Catchment Transit Time: Unresolved Issues.
IAEA: N. p.,
2013.
Web.
Darling, W. G., Gooddy, D. C., Barker, J. A., & Robinson, M.
Chalk Catchment Transit Time: Unresolved Issues.
IAEA.
Darling, W. G., Gooddy, D. C., Barker, J. A., and Robinson, M.
2013.
"Chalk Catchment Transit Time: Unresolved Issues."
IAEA.
@misc{etde_22123069,
title = {Chalk Catchment Transit Time: Unresolved Issues}
author = {Darling, W. G., Gooddy, D. C., Barker, J. A., and Robinson, M.}
abstractNote = {The mean transit time (MTT) of a catchment is the average residence time of water from rainfall to river outflow at the foot of the catchment. As such, MTT has important water quality as well as resource implications. Many catchments worldwide have been measured for MTT using environmental isotopes, yet the Chalk, an important aquifer in NW Europe, has received little attention in this regard. The catchment of the River Lambourn in southern England has been intermittently studied since the 1960s using isotopic methods. A tritium peak measured in the river during the 1970s indicates an apparent MTT of {approx}15 years, but the thick unsaturated zone (average {approx}50 m) of the catchment suggests that the MTT should be much greater because of the average downward movement through the Chalk of {approx}1 m/a consistently indicated by tritium and other tracers. Recent work in the catchment using SF{sub 6} as a residence time indicator has given groundwater ages in the narrow range 11-18 yrs, apparently supporting the river tritium data but in conflict with the unsaturated zone data even allowing for a moderate proportion of rapid bypass flow. The MTT of the catchment remains unresolved for the time being. (author)}
place = {IAEA}
year = {2013}
month = {Jul}
}
title = {Chalk Catchment Transit Time: Unresolved Issues}
author = {Darling, W. G., Gooddy, D. C., Barker, J. A., and Robinson, M.}
abstractNote = {The mean transit time (MTT) of a catchment is the average residence time of water from rainfall to river outflow at the foot of the catchment. As such, MTT has important water quality as well as resource implications. Many catchments worldwide have been measured for MTT using environmental isotopes, yet the Chalk, an important aquifer in NW Europe, has received little attention in this regard. The catchment of the River Lambourn in southern England has been intermittently studied since the 1960s using isotopic methods. A tritium peak measured in the river during the 1970s indicates an apparent MTT of {approx}15 years, but the thick unsaturated zone (average {approx}50 m) of the catchment suggests that the MTT should be much greater because of the average downward movement through the Chalk of {approx}1 m/a consistently indicated by tritium and other tracers. Recent work in the catchment using SF{sub 6} as a residence time indicator has given groundwater ages in the narrow range 11-18 yrs, apparently supporting the river tritium data but in conflict with the unsaturated zone data even allowing for a moderate proportion of rapid bypass flow. The MTT of the catchment remains unresolved for the time being. (author)}
place = {IAEA}
year = {2013}
month = {Jul}
}