A multi‐tracer approach to quantifying groundwater inflows to an upland river; assessing the influence of variable groundwater chemistry. Issue 1 (13th December 2013)

• Record Type: Journal Article
• Authors: Atkinson, A. P.; Cartwright, I.; Gilfedder, B. S.; Hofmann, H.; Unland, N. P.; Cendón, D. I.; Chisari, R.
• Is Part Of: Hydrological processes. Volume 29:Issue 1(2015:Jan.)
• Page Start: 1
• Page End: 12
• Publication Date: 2013-12-13
• Subjects: Hydrology -- Periodicals; Hydrology -- Research -- Periodicals; Hydrologic models -- Periodicals; Hydrological forecasting -- Periodicals; 631.432
• DOI: 10.1002/hyp.10122
• Languages: English
• ISSNs: 0885-6087

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>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 27 km 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 <sup>222</sup>Rn activities, Cl and <sup>3</sup>H concentrations imply the river receives substantial groundwater inflows. Mass balances based on <sup>222</sup>Rn, Cl and <sup>3</sup>H yield estimates of groundwater inflows that agree to within ± 12%, with cumulative inflows in individual campaigns ranging from 24 346 to 88 467 m<sup>3</sup>/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 5–10 km section where the river intersects the Eastern View Formation, a major regional aquifer. Groundwater <sup>222</sup>Rn activities over the 16 month period were spatially heterogeneous across the catchment, ranging between 2000 Bq/m<sup>3</sup> and 16 175 Bq/m<sup>3</sup>. Although groundwater <sup>222</sup>Rn activities display temporal variation, spatial variation in groundwater <sup>222</sup>Rn is a key control on <sup>222</sup>Rn mass balances in river catchments where groundwater and river <sup>222</sup>Rn activities are within an order of magnitude of each other. Calculated groundwater discharges vary from 8.4 to 15 m<sup>3</sup>/m/day when groundwater <sup>222</sup>Rn activities are varied by ± 1 σ. Copyright © 2013 John Wiley & Sons, Ltd.</p> </abstract>