Propagation of pressure change through thick clay sequences: an example from Liverpool Plains, NSW, Australia

Timms, Wendy; Acworth, R. I.

doi:10.1007/s10040-005-0436-7

Cited by 52 publications

(33 citation statements)

References 15 publications

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“…The lack of groundwater level response was to be expected given the large water holding capacity of the surface clays and the very low hydraulic conductivity limiting vertical flow through the vadose zone. This was in contrast to rapid groundwater level response in the Upper Namoi catchment (Timms and Acworth, 2005). The depth of the shallow saline water table had not previously been recorded in this area, as monitoring bores drilled in the 1960s had targeted high yielding deep aquifers and the shallowest monitoring bore screen was positioned at over 30 m depth in a semi-confined sand aquifer (GW036541-1).…”

Section: Groundwater Response To Large Rainfall Eventsmentioning

confidence: 83%

Implications of deep drainage through saline clay for groundwater recharge and sustainable cropping in a semi-arid catchment, Australia

Timms

Young

Huth

2012

Hydrol. Earth Syst. Sci.

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Abstract. The magnitude and timing of deep drainage and salt leaching through clay soils is a critical issue for dryland agriculture in semi-arid regions (<500 mm yr −1 rainfall, potential evapotranspiration >2000 mm yr −1 ) such as parts of Australia's Murray-Darling Basin (MDB). In this rare study, hydrogeological measurements and estimations of the historic water balance of crops grown on overlying Grey Vertosols were combined to estimate the contribution of deep drainage below crop roots to recharge and salinization of shallow groundwater. Soil sampling at two sites on the alluvial flood plain of the Lower Namoi catchment revealed significant peaks in chloride concentrations at 0.8-1.2 m depth under perennial vegetation and at 2.0-2.5 m depth under continuous cropping indicating deep drainage and salt leaching since conversion to cropping. Total salt loads of 91-229 t ha −1 NaCl equivalent were measured for perennial vegetation and cropping, with salinity to ≥10 m depth that was not detected by shallow soil surveys. Groundwater salinity varied spatially from 910 to 2430 mS m −1 at 21 to 37 m depth (N = 5), whereas deeper groundwater was less saline (290 mS m −1 ) with use restricted to livestock and rural domestic supplies in this area. The Agricultural Production Systems Simulator (APSIM) software package predicted deep drainage of 3.3-9.5 mm yr −1 (0.7-2.1 % rainfall) based on site records of grain yields, rainfall, salt leaching and soil properties. Predicted deep drainage was highly episodic, dependent on rainfall and antecedent soil water content, and over a 39 yr period was restricted mainly to the record wet winter of 1998. During the study period, groundwater levels were unresponsive to major rainfall events (70 and 190 mm total), and most piezometers at about 18 m depth remained dry. In this area, at this time, recharge appears to be negligible due to low rainfall and large potential evapotranspiration, transient hydrological conditions after changes in land use and a thick clay dominated vadose zone. This is in contrast to regional groundwater modelling that assumes annual recharge of 0.5 % of rainfall. Importantly, it was found that leaching from episodic deep drainage could not cause discharge of saline groundwater in the area, since the water table was several meters below the incised river bed.

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Section: Groundwater Response To Large Rainfall Eventsmentioning

confidence: 83%

Implications of deep drainage through saline clay for groundwater recharge and sustainable cropping in a semi-arid catchment, Australia

Timms

Young

Huth

2012

Hydrol. Earth Syst. Sci.

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“…This pressure increase reduces the internal shear strength of the landslide material at the sliding zone. Whereas a shallow landslide may also be triggered by intense and brief rainfall, a deep-seated landslide with a cover of low permeability is affected by events of long and moderate intensity (Timms and Acworth, 2005;Zhang et al, 2006). The change of groundwater regime is the most relevant factor that may induce a sliding acceleration.…”

Section: Discussionmentioning

confidence: 99%

Kinematics of a landslide derived from archival photogrammetry and GPS data

et al. 2008

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“…This phase lag was used to calculate the hydraulic conductivity ⟨ K ⟩ of a thick clay aquitard. Most notably, Timms and Acworth () found that the in situ calculated specific storage values were 2 orders of magnitude less than those derived from lab testing using core samples from the same monitoring well. They hypothesized that this difference must be a result of the stress differing between field and laboratory conditions (i.e., cores are not under in situ stress during testing).…”

Section: Impacts Of Eat On Groundwater Systemsmentioning

confidence: 99%

Utilizing the Impact of Earth and Atmospheric Tides on Groundwater Systems: A Review Reveals the Future Potential

McMillan

Rau

Timms

et al. 2019

Reviews of Geophysics

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Groundwater extraction is increasing rapidly in many areas of the world, causing serious impacts such as falling water tables, ground surface subsidence, water quality degradation, and reduction of stream baseflow on which many ecosystems depend. Methods for understanding and predicting the impacts of groundwater extraction generally lack detailed spatial and temporal knowledge of the subsurface hydrogeomechanical properties. This review provides a comprehensive understanding of Earth and atmospheric tides and their impact on subsurface pore pressure. First, we evaluate the global occurrence of Earth and atmospheric tides. Then, we illustrate their impact on the groundwater response and connect this with the theory of poroelasticity, which underpins quantitative analyses. Finally, we review methods that utilize these impacts to characterize groundwater systems and to quantify their hydrogeomechanical properties. We conclude by highlighting their potential as passive and low‐cost investigation techniques and by outlining the research and developments required to progress and make analyses readily available. Thus, hydrogeomechanical properties of subsurface systems could be obtained at unprecedented spatial and temporal resolution, adding additional value to commonly acquired groundwater and atmospheric pressure data.

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Propagation of pressure change through thick clay sequences: an example from Liverpool Plains, NSW, Australia

Cited by 52 publications

References 15 publications

Implications of deep drainage through saline clay for groundwater recharge and sustainable cropping in a semi-arid catchment, Australia

Implications of deep drainage through saline clay for groundwater recharge and sustainable cropping in a semi-arid catchment, Australia

Kinematics of a landslide derived from archival photogrammetry and GPS data

Utilizing the Impact of Earth and Atmospheric Tides on Groundwater Systems: A Review Reveals the Future Potential

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