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Peter G Cook - One of the best experts on this subject based on the ideXlab platform.
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Quantifying Surface Water, Porewater, and Groundwater Interactions Using Tracers: Tracer Fluxes, Water Fluxes, and End‐member Concentrations
Water Resources Research, 2018Co-Authors: Peter G Cook, Valenti Rodellas, Thomas StieglitzAbstract:Tracer approaches to estimate both porewater exchange (the cycling of water between surface water and sediments, with zero net water flux) and Groundwater Inflow (the net flow of terrestrially derived Groundwater into surface water) are commonly based on solute mass balances. However, this requires appropriate characterization of tracer end‐member concentrations in exchanging or discharging water. Where either porewater exchange or Groundwater Inflow to surface water occur in isolation, then the water flux is easily estimated from the net tracer flux if the end‐member is appropriately chosen. However, in most natural systems porewater exchange and Groundwater Inflow will occur concurrently. Our analysis shows that if Groundwater Inflow (Qg) and porewater exchange (Qp) mix completely before discharging to surface water, then the combined water flux (Qg + Qp) can be approximated by dividing the combined tracer flux by the difference between the porewater and surface water concentrations, (cp – c). If Qg and Qp do not mix prior to discharge, then (Qg + Qp) can only be constrained by minimum and maximum values. The minimum value is obtained by dividing the net tracer flux by the Groundwater concentration, and the maximum is obtained by dividing by (cp – c). Dividing by the Groundwater concentration gives a maximum value for Qg. If porewater exchange and Groundwater outflow occur concurrently, then dividing the net tracer flux by (cp – c) will provide a minimum value for Qp. Use of multiple tracers, and spatial and temporal replication should provide a more complete picture of exchange processes and the extent of subsurface mixing.
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On the limits of heat as a tracer to estimate reach‐scale river‐aquifer exchange flux
Water Resources Research, 2015Co-Authors: Peter G Cook, Craig T Simmons, Chunmiao ZhengAbstract:For the past few decades, heat has been used to estimate river-aquifer exchange flux at discrete locations by comparison of river and Groundwater temperature. In recent years, heat has also been employed to estimate reach-scale river-aquifer exchange flux based only on river temperature. However, there are many more parameters that govern heat exchange and transport in surface water than in Groundwater. In this study, we analyzed the sensitivities of surface water temperature to various parameters and assessed the accuracy of temperature-based estimates of exchange flux in two synthetic rivers and in a field setting. For the large synthetic river with a flow rate of 63 m3 s−1 (i.e., 5.44 × 106 m3 d−1), the upper and lower bounds of the Groundwater Inflow rate can be determined when the actual Groundwater Inflow is around 100 m2 d−1. For higher and lower fluxes, only minimum and maximum bounds respectively can be determined. For the small synthetic river with the flow rate of 0.63 m3 s−1 (i.e., 5.44 × 104 m3 d−1), the bounds of the Groundwater Inflow rate can only be estimated when the actual Groundwater Inflow rate is near 10 m2 d−1. In the field setting, results show that the Inflow rate must be less than 100 m2 d−1, but a lower bound for Groundwater Inflow cannot be determined. The large ranges of estimated Groundwater Inflow rates in both theoretical and field settings indicate the need to reduce parameter errors and combine heat measurements with other isotopic and/or chemical methods. This article is protected by copyright. All rights reserved.
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chemistry of Groundwater discharge inferred from longitudinal river sampling
Water Resources Research, 2014Co-Authors: Jordi Batlleaguilar, Glenn A Harrington, Marc Leblanc, Chani Welch, Peter G CookAbstract:We present an approach for identifying Groundwater discharge chemistry and quantifying spatially distributed Groundwater discharge into rivers based on longitudinal synoptic sampling and flow gauging of a river. The method is demonstrated using a 450 km reach of a tropical river in Australia. Results obtained from sampling for environmental tracers, major ions, and selected trace element chemistry were used to calibrate a steady state one-dimensional advective transport model of tracer distribution along the river. The model closely reproduced river discharge and environmental tracer and chemistry composition along the study length. It provided a detailed longitudinal profile of Groundwater Inflow chemistry and discharge rates, revealing that regional fractured mudstones in the central part of the catchment contributed up to 40% of all Groundwater discharge. Detailed analysis of model calibration errors and modeled/measured Groundwater ion ratios elucidated that Groundwater discharging in the top of the catchment is a mixture of local Groundwater and bank storage return flow, making the method potentially useful to differentiate between local and regional sourced Groundwater discharge. As the error in tracer concentration induced by a flow event applies equally to any conservative tracer, we show that major ion ratios can still be resolved with minimal error when river samples are collected during transient flow conditions. The ability of the method to infer Groundwater Inflow chemistry from longitudinal river sampling is particularly attractive in remote areas where access to Groundwater is limited or not possible, and for identification of actual fluxes of salts and/or specific contaminant sources.
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Quantifying Groundwater flows to streams using differential flow gaugings and water chemistry
Journal of Hydrology, 2012Co-Authors: James L. Mccallum, Peter G Cook, Dawit Berhane, Chris Rumpf, Gerard A. McmahonAbstract:Summary While estimates of net Groundwater Inflow to streams (Inflow minus outflow) can be made using differential flow gauging, the inclusion of water chemistry (tracer) measurements allows both Inflow and outflow to be separately quantified. In this paper we assess how the estimates of net and gross Groundwater Inflows are affected by the choice of tracer at three contrasting field sites. Groundwater flows are first estimated with differential flow gauging and then with the sequential addition of natural tracer data – electrical conductivity, chloride concentration and radon activity measurements. The final analysis is where an injected tracer experiment is also conducted to constrain the gas transfer velocity for radon. Groundwater Inflow rates were estimated by calibrating a numerical model which simulated flows and concentrations of tracers in the river. Although both the total Groundwater Inflow along the study reach and the spatial distribution of Inflow depended on the data used for the model calibration, the difference between the estimates was less than the prediction error. The analysis also showed that prediction error for Groundwater Inflow decreases as additional tracers are included in the analysis. The magnitude of the error reduction is related to the properties of the specific catchment. Generally, for a tracer to reduce uncertainty substantially the concentration of the tracer in Groundwater must be well defined, and the contrast between the concentration of the tracer in Groundwater and the river must be high.
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Groundwater Inflow to a shallow poorly mixed wetland estimated from a mass balance of radon
Journal of Hydrology, 2008Co-Authors: Peter G Cook, Cameron Wood, Troy White, Craig T Simmons, T Fass, Philip BrunnerAbstract:Summary Radon activity within a shallow wetland in southern Australia has been measured on three occasions between May and October 2006. Measured activities within the surface water display a similar pattern of spatial variability on each occasion, suggesting that it is related to the locations of Groundwater Inflow and mixing processes. The mean Groundwater Inflow rate has been estimated from the mean radon activity using a mass balance approach. The components of the radon budget are (i) contribution from Groundwater Inflow, (ii) diffusive flux from wetland bottom sediments (iii) loss due to gas exchange, (iv) loss due to radioactive decay, (v) loss due to Groundwater or surface water outflow. Also required to complete the water balance are the surface water Inflow rate, direct precipitation on the wetland, and evaporation rate. The radon diffusive flux has been estimated from measurements of radon production within the sediments and a diffusive transport model, calibrated by measurements of radon activity in sealed chambers that can receive radon only from diffusion and lose it only by radioactive decay. Radon loss due to gas exchange is inferred from the loss rate of SF6, following its injection into isolated areas of the wetland, while the rate of radioactive decay is known. The radon activity in Groundwater Inflow is measured from sampling piezometers surrounding the wetland. Steady state and transient mass balance approaches yield similar results, with Groundwater Inflow rates varying between 12 and 18 m3/day. Estimated Groundwater Inflow rates are most sensitive to the radon activity of Groundwater Inflow, the gas exchange velocity, surface water area and the accuracy with which the mean radon activity in the wetland can be measured. Importantly, it is relatively insensitive to the surface water Inflow rate, which is poorly known.
Jordan F Clark - One of the best experts on this subject based on the ideXlab platform.
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quantifying Groundwater discharge to cockburn river southeastern australia using dissolved gas tracers 222rn and sf6
Water Resources Research, 2006Co-Authors: Peter G Cook, Sebastien Lamontagne, D Berhane, Jordan F ClarkAbstract:[1] Groundwater discharge to the Cockburn River, southeast Australia, has been estimated from comparison of natural 222Rn activities in Groundwater and river water, interpreted using a numerical flow model that simulates longitudinal radon activities as a function of Groundwater Inflow, hyporheic exchange, evaporation, gas exchange with the atmosphere, and radioactive decay. An injection of SF6 into the river to estimate the gas transfer velocity assisted in constraining the model. Previous estimates of Groundwater Inflow using 222Rn activities have not considered possible input of radon due to exchange between river water and water in the hyporheic zone beneath the streambed. In this paper, radon input due to hyporheic exchange is estimated from measurements of radon production by hyporheic zone sediments and rates of water exchange between the river and the hyporheic zone. Total Groundwater Inflow to the Cockburn River is estimated to be 18500 m3/d, although failure to consider hyporheic exchange would cause overestimation of the volume of Groundwater Inflow by approximately 70%.
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Quantifying Groundwater discharge to Cockburn River, southeastern Australia, using dissolved gas tracers 222Rn and SF6
Water Resources Research, 2006Co-Authors: Peter G Cook, Sebastien Lamontagne, D Berhane, Jordan F ClarkAbstract:Groundwater discharge to the Cockburn River, southeast Australia, has been estimated from comparison of natural 222Rn activities in Groundwater and river water, interpreted using a numerical flow model that simulates longitudinal radon activities as a function of Groundwater Inflow, hyporheic exchange, evaporation, gas exchange with the atmosphere, and radioactive decay. An injection of SF6 into the river to estimate the gas transfer velocity assisted in constraining the model. Previous estimates of Groundwater Inflow using 222Rn activities have not considered possible input of radon due to exchange between river water and water in the hyporheic zone beneath the streambed. In this paper, radon input due to hyporheic exchange is estimated from measurements of radon production by hyporheic zone sediments and rates of water exchange between the river and the hyporheic zone. Total Groundwater Inflow to the Cockburn River is estimated to be 18500 m 3/d, although failure to consider hyporheic exchange would cause overestimation of the volume of Groundwater Inflow by approximately 70%. Copyright 2006 by the American Geophysical Union.
Hadi Farhadian - One of the best experts on this subject based on the ideXlab platform.
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Water flow into tunnels in discontinuous rock: a short critical review of the analytical solution of the art
Bulletin of Engineering Geology and the Environment, 2019Co-Authors: Hadi Farhadian, Arash Nikvar-hassaniAbstract:Indeed, determination of Groundwater Inflow into tunnels, especially in discontinuous rock masses, is still one of the most challenging issues faced by tunneling experts, which may have destructive consequences and result in impediments to tunneling operations. Hence, it is necessary to predict the location and amount of Inflow in the tunneling designation phase. In order to quantify the Groundwater Inflow rate into tunnels, various analytical, empirical, and numerical methods exist in the literature. Analytical solutions are of great interest since they provide desirable approximations quickly and without the necessity for advanced computers. However, there are no comprehensive and unique databases concerning analytical methods. Therefore, the attempt of this study was to present the various analytical methods that exist in the literature, their application domain, and their validation.
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a comparative study on evaluation of steady state Groundwater Inflow into a circular shallow tunnel
Tunnelling and Underground Space Technology, 2018Co-Authors: Arash Nikvar Hassani, Hadi Farhadian, Homayoon KatibehAbstract:Abstract The objective of this study is to make a comparison among different methods used for evaluation of steady state Groundwater Inflow to a shallow circular cross section tunnel. These methods include: analytical solutions, empirical methods and numerical modelling. Analytical formulas provide an estimation of Inflow rate based on some simplifying assumptions which are somehow unrealistic. Therefore, their results are over/underestimated. Empirical methods are presented based on the experiences of different tunnel projects and they mostly provide an appropriate qualitative estimation; while, their quantitative predictions are not desirable. Despite analytical and empirical approaches, numerical modelling is a suitable tool for solving complex geomechanical and hydrogeological conditions. Hence, their results are more reliable and precise for designation of efficient drainage systems. In this study, Groundwater Inflow into Tabriz Metro-Line 2 (TML2) is evaluated by means of these methods and their results were compared. The results indicated that all of the methods provide consistent results, however, it is inferred that in the absence of sufficient data, Raymer equation can provide more reliable estimation of Inflow rate for shallow tunnels in comparison to other analytical and empirical solutions due to its higher correlation with numerical results.
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Groundwater Inflow assessment to karaj water conveyance tunnel northern iran
Ksce Journal of Civil Engineering, 2017Co-Authors: Hadi Farhadian, Arash Nikvar Hassani, Homayoon KatibehAbstract:In this paper, Groundwater Inflow into Karaj Water Conveyance (KWC) tunnel was estimated using analytical and numerical methods in 12 different sections of the tunnel length. Further, these sections were rated from Groundwater hazard point of view by means of Site Groundwater Rating (SGR) factor. Comparing results show a reasonable accordance between observed water ingress rate and those various methods. Since, KWC tunnel is excavated in fractured rocks with a high level of anisotropy, analytical methods provided highly overestimated water Inflow rate. Furthermore all SGR, analytical and numerical results, show high levels of water Inflow from fault zones. Maximum water Inflow into tunnel was computed as 0.0536 and 0.0432 lit/sec/m using analytical and numerical methods, respectively. Based on SGR method, 11 out of 12 sections in KWC tunnel length are found to be in “No Risk” class with Groundwater Inflow of less than 0.04 lit/sec/m which are in agreement with analytical and numerical seepage values and also with the observed Inflow rate.
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numerical analysis of steady state Groundwater Inflow into tabriz line 2 metro tunnel northwestern iran with special consideration of model dimensions
Bulletin of Engineering Geology and the Environment, 2016Co-Authors: Arash Nikvar Hassani, Hadi Farhadian, Homayoon KatibehAbstract:In order to prevent problems like casualties, delays in tunneling procedure, and increasing tunneling costs, predicting Groundwater Inflow into tunnels and designing an efficient drainage system are necessary. Several analytical solutions exist in the literature, but they cannot accurately estimate Groundwater Inflow due to simplifying assumptions. Numerical methods, however, are increasingly used to predict Groundwater Inflow with higher accuracy. This study is aimed at predicting the steady state Groundwater ingress into Tabriz line 2 metro tunnel (TML2: a shallow urban tunnel) by considering model dimensions as critical factors in the numerical analysis process. A 2-D numerical finite element analysis of steady state Groundwater Inflow was performed along the tunnel based on geological and geotechnical investigations. Water Inflow into TML2 was then estimated based on optimum model dimensions. The total amount of Groundwater Inflow into TML2 was estimated to be 7013.6 l/min. The maximum cumulative water Inflow into the tunnel was also predicted to occur between 15.55 and 16.25 km in the tunnel with a 4754 l/min Inflow rate, which demands an effective drainage program. Finally, for validation of the methodology Groundwater Inflow values obtained through 2D finite element analysis were compared to those calculated with a well-known Inflow evaluation method (Raymer solution).
Markus Weiler - One of the best experts on this subject based on the ideXlab platform.
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quantification of localized Groundwater Inflow into streams using ground based infrared thermography
Geophysical Research Letters, 2011Co-Authors: Tobias Schuetz, Markus WeilerAbstract:[1] Due to temperature differences of Groundwater and streamwater, localized Groundwater Inflows into small streams can directly be detected with ground-based thermographic systems in summer or winter. Infrared radiation temperatures of surface water were used to determine mixing length and to calculate the relative fraction of Groundwater Inflow to downstream discharge. These fractions were comparable to Groundwater Inflow fractions derived from electrical conductivity, kinetic water temperatures and discharge measurements. This approach advances the immediate detection and quantification of localized Groundwater Inflow for hydrology, geology and ecology.
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Quantification of localized Groundwater Inflow into streams using ground‐based infrared thermography
Geophysical Research Letters, 2011Co-Authors: Tobias Schuetz, Markus WeilerAbstract:[1] Due to temperature differences of Groundwater and streamwater, localized Groundwater Inflows into small streams can directly be detected with ground-based thermographic systems in summer or winter. Infrared radiation temperatures of surface water were used to determine mixing length and to calculate the relative fraction of Groundwater Inflow to downstream discharge. These fractions were comparable to Groundwater Inflow fractions derived from electrical conductivity, kinetic water temperatures and discharge measurements. This approach advances the immediate detection and quantification of localized Groundwater Inflow for hydrology, geology and ecology.
S. Tickell - One of the best experts on this subject based on the ideXlab platform.
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Determining natural Groundwater influx to a tropical river using radon, chlorofluorocarbons and ionic environmental tracers
Journal of Hydrology, 2003Co-Authors: Peter G Cook, Guillaume Favreau, J. C. Dighton, S. TickellAbstract:Measurements of 222Rn, CFC-11, CFC-12, major ions and temperature of river water and springs are used to quantify rates of Groundwater Inflow to a tropical lowland river in the Northern Territory of Australia. Groundwater Inflow results in increases in 222Rn concentrations within the river, but decreases in concentrations of CFC-11 and CFC-12, because the Inflowing Groundwater is relatively old. 222Rn, CFC-11 and CFC-12 concentrations are affected by gas exchange with the atmosphere, while ion concentrations are not. Additionally, CFC concentrations in the river appear to have been increased by air entrapment and dissolution during turbulent flow at river rapids. Because the regional Groundwater is old, CFC concentrations in Groundwater Inflow are zero. In contrast, 222Rn and ion concentrations in the river are very sensitive to concentrations of these tracers in Groundwater Inflow. Numerical simulation of 222Rn, CFC-11 and CFC-12 stream concentrations allows the Groundwater Inflow rate, gas transfer velocity and air entrapment coefficient to be reasonably accurately constrained.
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Determining natural Groundwater influx to a tropical river using radon, chlorofluorocarbons and ionic environmental tracers
Journal of Hydrology, 2003Co-Authors: P. G. Cook, Guillaume Favreau, J. C. Dighton, S. TickellAbstract:Measurements of222Rn, CFC- 11, CFC- 12, major ions and temperature of river water and springs are used to quantify rates of Groundwater Inflow to a tropical lowland river in the Northern Territory of Australia. Groundwater Inflow results in increases in222Rn concentrations within the river, but decreases in concentrations of CFC-11 and CFC-12, because the Inflowing Groundwater is relatively old.222Rn, CFC-11 and CFC-12 concentrations are affected by gas exchange with the atmosphere, while ion concentrations are not. Additionally, CFC concentrations in the river appear to have been increased by air entrapment and dissolution during turbulent flow at river rapids. Because the regional Groundwater is old, CFC concentrations in Groundwater Inflow are zero. In contrast,222Rn and ion concentrations in the river are very sensitive to concentrations of these tracers in Groundwater Inflow. Numerical simulation of222Rn, CFC-11 and CFC-12 stream concentrations allows the Groundwater Inflow rate, gas transfer velocity and air entrapment coefficient to be reasonably accurately constrained. Crown Copyright © 2003 Published by Elsevier Science B.V. All rights reserved.
