Convergent tracer tests in multilayered aquifers: The importance of vertical flow in the injection borehole

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@article{c26c5ef8033243019a56116cb69dc4e5,
title = "Convergent tracer tests in multilayered aquifers: The importance of vertical flow in the injection borehole",
abstract = "A mathematical model describing the steady state flows in a forced gradient tracer test between an injection and pumping borehole in a multilayered sandstone aquifer has been developed that includes the effect of vertically variable background heads. A second model describing the recovery of tracer from a layer in which there are discharges due to vertical flow in the injection borehole is also presented. Application of the models to field tracer test data indicates that the observed recoveries, which are not proportional to the abstraction rate in each layer, are consistent with the hydraulic behavior of the aquifer when natural vertical head gradients are taken into account. Investigation with the models illustrates that the vertical distribution of tracer recovery depends strongly upon the background heads and that tracer tests conducted in the same aquifer, but at different times, may interrogate different aquifer layers. It is also shown generally that for a given abstraction rate the vertical distribution of tracer recovery in small-scale tracer tests is controlled largely by the transmissivity distribution but that as the spatial scale of the test increases, the distribution of recovery becomes proportional to the discharges from the injection borehole because of vertical flows within it, which may be natural or induced by pumping in the monitoring borehole. Uncertainties inherent in the design of forced gradient tracer tests in multilayered aquifers and the problems of applying the results of such tests to natural gradient contaminant migration are discussed.",
author = "Michael Riley and John Tellam and Richard Greswell and V Durand and MF Aller",
year = "2011",
month = jul
day = "1",
doi = "10.1029/2010WR009838",
language = "English",
volume = "47",
pages = "W07501",
journal = "Water Resources Research",
issn = "0043-1397",
publisher = "American Geophysical Union",

}

RIS

TY - JOUR

T1 - Convergent tracer tests in multilayered aquifers: The importance of vertical flow in the injection borehole

AU - Riley, Michael

AU - Tellam, John

AU - Greswell, Richard

AU - Durand, V

AU - Aller, MF

PY - 2011/7/1

Y1 - 2011/7/1

N2 - A mathematical model describing the steady state flows in a forced gradient tracer test between an injection and pumping borehole in a multilayered sandstone aquifer has been developed that includes the effect of vertically variable background heads. A second model describing the recovery of tracer from a layer in which there are discharges due to vertical flow in the injection borehole is also presented. Application of the models to field tracer test data indicates that the observed recoveries, which are not proportional to the abstraction rate in each layer, are consistent with the hydraulic behavior of the aquifer when natural vertical head gradients are taken into account. Investigation with the models illustrates that the vertical distribution of tracer recovery depends strongly upon the background heads and that tracer tests conducted in the same aquifer, but at different times, may interrogate different aquifer layers. It is also shown generally that for a given abstraction rate the vertical distribution of tracer recovery in small-scale tracer tests is controlled largely by the transmissivity distribution but that as the spatial scale of the test increases, the distribution of recovery becomes proportional to the discharges from the injection borehole because of vertical flows within it, which may be natural or induced by pumping in the monitoring borehole. Uncertainties inherent in the design of forced gradient tracer tests in multilayered aquifers and the problems of applying the results of such tests to natural gradient contaminant migration are discussed.

AB - A mathematical model describing the steady state flows in a forced gradient tracer test between an injection and pumping borehole in a multilayered sandstone aquifer has been developed that includes the effect of vertically variable background heads. A second model describing the recovery of tracer from a layer in which there are discharges due to vertical flow in the injection borehole is also presented. Application of the models to field tracer test data indicates that the observed recoveries, which are not proportional to the abstraction rate in each layer, are consistent with the hydraulic behavior of the aquifer when natural vertical head gradients are taken into account. Investigation with the models illustrates that the vertical distribution of tracer recovery depends strongly upon the background heads and that tracer tests conducted in the same aquifer, but at different times, may interrogate different aquifer layers. It is also shown generally that for a given abstraction rate the vertical distribution of tracer recovery in small-scale tracer tests is controlled largely by the transmissivity distribution but that as the spatial scale of the test increases, the distribution of recovery becomes proportional to the discharges from the injection borehole because of vertical flows within it, which may be natural or induced by pumping in the monitoring borehole. Uncertainties inherent in the design of forced gradient tracer tests in multilayered aquifers and the problems of applying the results of such tests to natural gradient contaminant migration are discussed.

U2 - 10.1029/2010WR009838

DO - 10.1029/2010WR009838

M3 - Article

VL - 47

SP - W07501

JO - Water Resources Research

JF - Water Resources Research

SN - 0043-1397

ER -