Karst aquifers are a vital groundwater resource globally, but features such as rapid recharge and conduit flow make them highly vulnerable to land-surface contamination. We apply environmental age tracers to the south-central Texas Edwards aquifer, a karst resource in a rapidly urbanizing and drought-prone region, to assess vulnerability to land-surface contamination and risks unique to karst aquifers. We show that vulnerability of Edwards aquifer groundwater follows similar spatial and depth patterns common to porous-media type aquifers, despite complicated karst hydrogeologic features. Shallow and unconfined parts are more vulnerable to land-surface contamination than the deeper and confined parts, although even the oldest groundwater is mixed with some recent recharge. When modeled age-tracer results are coupled with other independent geochemical tracers of water-rock interaction specific to karst settings, they can yield insight into residence time and associated vulnerability.
|Title||Karst groundwater vulnerability determined by modeled age and residence time tracers|
|Authors||MaryLynn Musgrove, Bryant Jurgens, Stephen P. Opsahl|
|Publication Subtype||Journal Article|
|Series Title||Geophysical Research Letters|
|Record Source||USGS Publications Warehouse|
|USGS Organization||California Water Science Center; Oklahoma-Texas Water Science Center|