TY - JOUR
T1 - Identifying the contribution of regional groundwater to the baseflow of a tropical river (Daly River, Australia)
AU - Smerdon, Brian
AU - Gardner, W. Payton
AU - Harrington, Glenn
AU - Tickell, Steven
PY - 2012/9/25
Y1 - 2012/9/25
N2 - A mixture of older regional-scale groundwater flow and relatively modern local-scale groundwater was identified as the source of baseflow to a perennial river in a tropical savanna. Multiple environmental tracers, including 222Rn, CFCs, SF 6, and 4He were measured in the river, groundwater, and springs along a 60km segment of the Daly River in the Northern Territory of Australia. At the location where a group of springs intersected the river, groundwater discharge contained elevated 4He and very low concentrations of CFCs and SF 6. This influx of regional-scale groundwater could be detected at downstream locations in the river and was used to parameterize a one-dimensional model for estimating the groundwater discharge flux. Upstream and downstream of the springs, the source of baseflow is composed of waters containing SF 6 and CFCs from local-scale groundwater sources adjacent to the river. Within 1km of the river, a redox fence was detected, with reducing conditions leading to degradation of CFCs that could have masked detecting the contribution of local-scale sources. This study confirmed the applicability of a new technique using 4He to identify regional-scale groundwater flow contributions to rivers, and demonstrated that multi-tracer studies are needed to identify the locations, rates, and sources of baseflow.
AB - A mixture of older regional-scale groundwater flow and relatively modern local-scale groundwater was identified as the source of baseflow to a perennial river in a tropical savanna. Multiple environmental tracers, including 222Rn, CFCs, SF 6, and 4He were measured in the river, groundwater, and springs along a 60km segment of the Daly River in the Northern Territory of Australia. At the location where a group of springs intersected the river, groundwater discharge contained elevated 4He and very low concentrations of CFCs and SF 6. This influx of regional-scale groundwater could be detected at downstream locations in the river and was used to parameterize a one-dimensional model for estimating the groundwater discharge flux. Upstream and downstream of the springs, the source of baseflow is composed of waters containing SF 6 and CFCs from local-scale groundwater sources adjacent to the river. Within 1km of the river, a redox fence was detected, with reducing conditions leading to degradation of CFCs that could have masked detecting the contribution of local-scale sources. This study confirmed the applicability of a new technique using 4He to identify regional-scale groundwater flow contributions to rivers, and demonstrated that multi-tracer studies are needed to identify the locations, rates, and sources of baseflow.
KW - Baseflow
KW - Environmental tracers
KW - Regional groundwater
KW - Springs
KW - Surface water-groundwater interaction
UR - http://www.scopus.com/inward/record.url?scp=84866184390&partnerID=8YFLogxK
U2 - 10.1016/j.jhydrol.2012.06.058
DO - 10.1016/j.jhydrol.2012.06.058
M3 - Article
SN - 0022-1694
VL - 464-465
SP - 107
EP - 115
JO - Journal of Hydrology
JF - Journal of Hydrology
ER -