The response of aquifers to periodic forcing

Townley, Lloyd R.

doi:10.1016/0309-1708(95)00008-7

Cited by 153 publications

(199 citation statements)

References 12 publications

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“…[10] A useful generalization of these analytical results was developed by Townley [1995], who described the response of a one-dimensional, or radially symmetrical, confined aquifer of finite length to a large number of periodic boundary conditions, including all possible combinations of specified head, specified flow, and mixed boundary conditions. The reader is referred to Townley's paper for complete details and for a general sense of response to periodic forcing for various parameter values and boundary conditions.…”

Section: Theorymentioning

confidence: 99%

“…[11] Among the conditions considered by Townley [1995] is one-dimensional flow within a confined aquifer:…”

Section: Theorymentioning

confidence: 99%

“…It may then be assumed that recharge estimates can be systematically distributed within similar environments in the watershed to represent climatically driven inflows for groundwater flow simulations [Hanson et al, 2002]. The advantages of using an analytical model, such as that of Townley [1995], include its simplicity to program and model, and its ability to provide an estimate of time-varying recharge using few water level records without the construction of a large regional flow model.…”

Section: Introductionmentioning

confidence: 99%

“…This technique would be applicable for any boundary condition that represents a line source that is typical of mountain front recharge in the southwestern United States. For more humid regions where a distributed source of recharge may dominate, Townley [1995] presents extended solutions for these two-dimensional sources.…”

Section: Introductionmentioning

confidence: 99%

“…[8] The objectives of this analysis were to (1) develop and test a methodology to estimate time-varying recharge to basins using a numerical model of an idealized flow system that served as a surrogate for a typical alluvial aquifer in the southwestern United States, (2) evaluate, by inverse analysis of the Townley [1995] model, inferred estimates of timevarying recharge of a single period as well as a complex recharge pattern of multiple periodic components that are similar to known climate periods, (3) examine the effect of monitoring well locations along the flow line on the recharge estimates, and (4) demonstrate the methodology using actual data and compare the inferred periodic recharge to a long-term average estimate from a calibrated flow model.…”

Section: Introductionmentioning

confidence: 99%

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Inferring time‐varying recharge from inverse analysis of long‐term water levels

Dickinson

Hanson

Ferré

et al. 2004

Water Resources Research

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[1] Water levels in aquifers typically vary in response to time-varying rates of recharge, suggesting the possibility of inferring time-varying recharge rates on the basis of longterm water level records. Presumably, in the southwestern United States (Arizona, Nevada, New Mexico, southern California, and southern Utah), rates of mountain front recharge to alluvial aquifers depend on variations in precipitation rates due to known climate cycles such as the El Niño-Southern Oscillation index and the Pacific Decadal Oscillation. This investigation examined the inverse application of a one-dimensional analytical model for periodic flow described by Lloyd R. Townley in 1995 to estimate periodic recharge variations on the basis of variations in long-term water level records using southwest aquifers as the case study. Time-varying water level records at various locations along the flow line were obtained by simulation of forward models of synthetic basins with applied sinusoidal recharge of either a single period or composite of multiple periods of length similar to known climate cycles. Periodic water level components, reconstructed using singular spectrum analysis (SSA), were used to calibrate the analytical model to estimate each recharge component. The results demonstrated that periodic recharge estimates were most accurate in basins with nearly uniform transmissivity and the accuracy of the recharge estimates depends on monitoring well location. A case study of the San Pedro Basin, Arizona, is presented as an example of calibrating the analytical model to real data.

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Section: Theorymentioning

confidence: 99%

“…[11] Among the conditions considered by Townley [1995] is one-dimensional flow within a confined aquifer:…”

Section: Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Inferring time‐varying recharge from inverse analysis of long‐term water levels

Dickinson

Hanson

Ferré

et al. 2004

Water Resources Research

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Straight thinking about groundwater recession

Cuthbert

2014

Water Resources Research

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While in catchment and hillslope hydrology a more nuanced approach is now taken to streamflow recession analysis, in the context of major aquifers it is commonly still assumed that the groundwater head recession rate will take exponential form, an idea originally proposed in the 19th Century. However it is shown here that, in early times, the groundwater head recession in a major aquifer should take an almost straight line form with a rate approximately equal to the long-term recharge rate divided by the aquifer storage coefficient. The length of this phase can be estimated from an analytical expression derived in the paper which depends on the aquifer diffusivity, length scale, and the position of the monitoring point. A transitional phase then leads to an exponential phase after some critical time which is independent of the position of the monitoring point. Major aquifers in a state of periodic quasi-steady state are expected to have rates of groundwater flux recession which deviate little from the average rate of groundwater recharge. Where quasi-exponential groundwater declines are observed in nature, their form may be diagnostic of particular types of aquifer properties and/or boundary effects, such as proximity to drainage boundaries, variations in transmissivity with hydraulic head, storage changes due to pumping, nonequilibrium flow at a range of spatial and temporal scales, and variations in specific yield with depth. Recession analysis has applicability to a range of groundwater problems and is powerful way of gaining insight into the hydrologic functioning of an aquifer.

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Inference of long-term groundwater flow transience using environmental tracers: A theoretical approach

Massoudieh

2013

Water Resour. Res.

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[1] Under transient flow conditions, the groundwater age distribution (GAD) is affected by both the physical characteristics of the aquifer, such as the hydraulic conductivity field, and the past temporal flow variations. Therefore, measuring the concentration of single or multiple tracers in a water sample collected at one time does not provide sufficient information on the transient nature of groundwater flows. However, obtaining multiple tracers at different times may contain such information. To find the temporal relationship between the GADs at a certain location, and to gain understanding about the current characteristics of an aquifer using environmental tracers, it is useful to separate the effects of temporal flow variations from that of the aquifer structure. In this paper, a new approach is presented, aiming at establishing a link between a reference residence time distribution based on steady-state flow and the transient age distributions at different times. Such information allows us to look collectively at sets of tracers measured at different times, when inferring aquifer structure and temporal trends in flow. The potential of using multiple tracers collected at different times to infer the GAD and its temporal variations is shown through two demonstration cases where measurements of CFCs, SF 6 , and 85 Kr in hypothetical water samples are used to infer the overall temporal flow pattern in the aquifer. Bayesian inverse modeling via Markov Chain Monte Carlo method was used to estimate lumped-parameter groundwater ages and temporal flow patterns.

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The response of aquifers to periodic forcing

Cited by 153 publications

References 12 publications

Inferring time‐varying recharge from inverse analysis of long‐term water levels

Inferring time‐varying recharge from inverse analysis of long‐term water levels

Straight thinking about groundwater recession

Inference of long-term groundwater flow transience using environmental tracers: A theoretical approach

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