The effect of loading efficiency on the groundwater response to water level changes in shallow lakes and streams

Bakker, Mark

doi:10.1002/2015wr017977

Cited by 14 publications

(13 citation statements)

References 27 publications

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“…The ground surface displacement amplitude of ~4 mm is ten times greater than for the 'IN' scenario but is still very small in comparison to the annual variability of order 10 cm measured by GPS (Steckler et al, 2010). The 'LD' behaviour can be interpreted by means of a decomposition of heads in the manner shown by Anochikwa et al (Anochikwa et al, 2012) (see Supporting Information).…”

Section: The Hydraulically Disconnected Load Scenario ('Ld')mentioning

confidence: 76%

“…ℎ = + ), and to metres of load (i.e. = ⁄ , where (kg m -3 ) is the density of water and (m s -2 ) is the acceleration due to gravity) (Anochikwa et al, 2012;van der Kamp and Schmidt, 1997) gives:…”

Section: Analytical Solutionmentioning

confidence: 99%

“…Barometric efficiency measurements operationally consider short-term pore pressure changes likely corresponding to the response of relatively stiff aquifer sands, whereas pressure changes in clays are expected to become significant in the longer term. Where short-term moisture loading effects are the key interest (Anochikwa et al, 2012;Bardsley and Campbell, 2000), values for loading efficiency derived from barometric efficiency may be the most appropriate. Here however our main concern is for poromechanical consistency and for water load changes operating over a range of time scales, therefore we adopt Ss estimates based on aquifer pumping tests and use the corresponding and E values ( Figure 3).…”

Section: Uniformmentioning

confidence: 99%

“…In the case of partial coupling, changes to the mechanical load due to the changing mass of water near or at the surface may be included within the flow equation, onedimensionally in the vertical direction, and the solutions will satisfy all the equilibrium and compatibility requirements for stress and strain. There is no need to solve the elastic equation in order to calculate pressures in the aquifer, although once the flow equation is solved, the pressures can be substituted into the elastic equation to provide stresses and strains (Anochikwa et al, 2012). A sub-set of this partially-coupled condition occurs where there is negligible groundwater flow, due to very low hydraulic gradients, low permeability or a combination of both.…”

Section: Introductionmentioning

confidence: 99%

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Summary of responses

Woodman¹

2018

Preprint

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The coupled poro-mechanical behaviour of geologic-fluid systems is fundamental to numerous processes in structural geology, seismology and geotechnics but is frequently overlooked in hydrogeology. Substantial poro-mechanical influences on groundwater head have recently been highlighted in the Bengal Aquifer System, however, driven by terrestrial water loading across the Ganges-Brahmaputra-Meghna floodplains. Groundwater management in this strategically important fluvio-deltaic aquifer, the largest in south Asia, requires a coupled hydro-mechanical approach which acknowledges poroelasticity. We present a simple partially-coupled, one-dimensional poro-elastic model of the Bengal Aquifer System, and explore the poro-mechanical responses of the aquifer to surface boundary conditions representing hydraulic head and mechanical load under three modes of terrestrial water variation. The characteristic responses, shown as amplitude and phase of hydraulic head in depth profile and of ground surface deflection, demonstrate (i) the limits to using water levels in piezometers to indicate groundwater recharge, as conventionally applied in groundwater resources management; (ii) the conditions under which piezometer water levels respond primarily to changes in the mass of terrestrial water storage, as applied in geological weighing lysimetry; (iii) the relationship of ground surface vertical deflection to changes in groundwater storage;and (iv) errors of attribution that could result from ignoring the poroelastic behaviour of the aquifer. These concepts are illustrated through application of the partially-coupled model to interpret multi-level piezometer data at two sites in southern Bangladesh. There is a need for further research into the coupled responses of the aquifer due to more complex forms of surface loading, particularly from rivers.

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Section: The Hydraulically Disconnected Load Scenario ('Ld')mentioning

confidence: 76%

Section: Analytical Solutionmentioning

confidence: 99%

Section: Uniformmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Woodman¹

2018

Preprint

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“…The head in the aquifer below the sea is governed by (e.g., Bakker, ; Van der Kamp, )

T \frac{\partial^{2} h}{\partial x^{2}} = S \frac{\partial h}{\partial t} + q_{t} - S β \frac{normald h_{0}}{normald t} x \leq 0,

where β is the loading efficiency (also called tidal efficiency in studies of coastal aquifers), h is the head change caused by tidal fluctuations, and q t is the vertical specific discharge at the top of the aquifer (positive when the water flows vertically upward). Flow in the aquifer below the land is obtained from by setting the head h 0 above the aquifer equal to zero, which gives

\overset{T}{true} \frac{\partial^{2} h}{\partial x^{2}} = \overset{S}{true} \frac{\partial h}{\partial t} + {\overset{q}{true}}_{t} x \geq 0 .

…”

Section: One‐dimensional Flow To a Shallow Sea With Tidal Fluctuationsmentioning

confidence: 99%

Analytic Solutions for Tidal Propagation in Multilayer Coastal Aquifers

Bakker

2019

Water Resources Research

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A new analytic solution is presented for tidal propagation in multilayer coastal aquifers consisting of an arbitrary number of layers. The solution is derived using matrix calculus and may be applied to simulate tidal propagation in systems where aquifer layers are separated by leaky layers of low permeability or in stratified aquifers. The head, amplitude, and phase shift may be simulated for arbitrary tidal components. The transmissivity, storage coefficient, and loading efficiency may be different for every aquifer layer. Similarly, the resistance to vertical flow, storage coefficient, and loading efficiency may be different for every leaky layer. The aquifer system extends an infinite distance below the sea or may end abruptly at the shore line. In the former case, different aquifer and leaky layer properties may be specified below the sea and below the land. A homogeneous unconfined aquifer is simulated with 80 layers to demonstrate that the tidal signal propagates much farther inland in the deeper part than in the shallower part of an unconfined aquifer. This effect is enhanced significantly when layers of low permeability are present in the aquifer, even when these layers are fairly thin, such as clay lenses. The solution is implemented in Python and may be used, for example, to estimate aquifer parameters from head measurements in coastal aquifers.

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Review: Moisture loading—the hidden information in groundwater observation well records

Kamp

Schmidt

2017

Hydrogeol J

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The effect of loading efficiency on the groundwater response to water level changes in shallow lakes and streams

Cited by 14 publications

References 27 publications

Summary of responses

Summary of responses

Analytic Solutions for Tidal Propagation in Multilayer Coastal Aquifers

Review: Moisture loading—the hidden information in groundwater observation well records

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