科研之友
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摘要
Understanding the behaviour and variability of environmental tracers is important for their use in estimating groundwater discharge to rivers. This study utilizes a multi-tracer approach to quantify groundwater discharge into a 27km upland reach of the Gellibrand River in southwest Victoria, Australia. Ten sampling campaigns were conducted between March 2011 and June 2012, and the distribution of Rn-222 activities, Cl and H-3 concentrations imply the river receives substantial groundwater inflows. Mass balances based on Rn-222, Cl and H-3 yield estimates of groundwater inflows that agree to within +/- 12%, with cumulative inflows in individual campaigns ranging from 24346 to 88467m(3)/day along the studied river section. Groundwater discharge accounts for between 10 and 50% of river flow dependent on the time of year, with a high proportion (>40 %) of groundwater sustaining summer flows. Groundwater inflow is largely governed by regional groundwater flowpaths; between 50 and 90% of total groundwater inflows occur along a narrow 5-10km section where the river intersects the Eastern View Formation, a major regional aquifer. Groundwater Rn-222 activities over the 16month period were spatially heterogeneous across the catchment, ranging between 2000Bq/m(3) and 16175Bq/m(3). Although groundwater Rn-222 activities display temporal variation, spatial variation in groundwater Rn-222 is a key control on Rn-222 mass balances in river catchments where groundwater and river Rn-222 activities are within an order of magnitude of each other. Calculated groundwater discharges vary from 8.4 to 15m(3)/m/day when groundwater Rn-222 activities are varied by +/- 1 sigma.
- 出版日期2015-1-1
