Vertical groundwater storage properties and changes in confinement determined using hydraulic head response to atmospheric tides

Abstract

Accurate determination of groundwater state of confinement and compressible storage properties at vertical resolution over depth is notoriously difficult. We use the hydraulic head response to atmospheric tides at 2 cpd frequency as a tracer to quantify barometric efficiency (BE) and specific storage (Ss) over depth. Records of synthesized Earth tides, atmospheric pressure, and hydraulic heads measured in nine piezometers completed at depths between 5 and 55 m into unconsolidated smectitic clay and silt, sand and gravel were examined in the frequency domain. The barometric efficiency increased over depth from ∼0.05 in silty clay to ∼0.15 in sands and gravels. BE for silty clay was confirmed by calculating the loading efficiency as 0.95 using rainfall at the surface. Specific storage was calculated using effective rather than total moisture. The differences in phase between atmospheric pressure and hydraulic heads at 2 cpd were ∼180° below 10 m indicating confined conditions despite the low BE. Heads in the sediment above a fine sand and silt layer at 12 m exhibited a time variable phase difference between 0° and 180° indicating varying confinement. Our results illustrate that the atmospheric tide at 2 cpd is a powerful natural tracer for quantifying groundwater state of confinement and compressible storage properties in layered formations from hydraulic heads and atmospheric pressure records without the need for externally induced hydraulic stress. This approach could significantly improve the development of conceptual hydrogeological model used for groundwater resource development and management.

Quantifying Compressible Groundwater Storage by Combining Cross‐Hole Seismic Surveys and Head Response to Atmospheric Tides

“…Figure e compares the three specific storage estimates calculated using Equation (for the single value of L E at 16‐m depth). This is the conventional analysis that is based upon Jacob () and is implemented in Acworth et al (). Equation with values calculated for K s =42 GPa ( α < 1) as well as ( α = 1). This is a fully developed poroelastic solution where knowledge of parameters are required, that is, estimates for porosity, drained bulk modulus K , solid grain modulus K s , and shear modulus G or Poisson ratio μ . Equation with values calculated for K s =42 GPa ( α < 1) as well as ( α = 1).…”

“…Data for three different BE values across the possible range from 0 to 1.0 (Acworth, Halloran, et al, 2016) and for a profile of 10 different depths at a single site were described (Acworth et al, 2017). Acworth et al (2017) used the BE analysis to predict specific storage using the formulation of Jacob (1940). However, Van Der Kamp and Gale (1983) and Domenico (1983) noted (independently) that the approach of Jacob (1940) was based on a one-dimensional analysis that neglects the possibility of horizontal movement and also assumes that the compressibility of individual grains is insignificant.…”

The Influence of Syndepositional Macropores on the Hydraulic Integrity of Thick Alluvial Clay Aquitards

“…The depth to the saturated zone at this site is less than a meter or two below ground (Acworth et al, ; Timms & Acworth, ). Pore pressures within the clay sediments respond to barometric and earth tide strains and loading of moisture within the surface soils (Acworth et al, ).…”

“…The depth to the saturated zone at this site is less than a meter or two below ground (Acworth et al, ; Timms & Acworth, ). Pore pressures within the clay sediments respond to barometric and earth tide strains and loading of moisture within the surface soils (Acworth et al, ). Swelling during wetting of these smectite soils was observed to close surface cracks that were up to 30 mm wide, resulting in a more homogeneous soil (Greve et al, ).…”

Comparing Methods of Barometric Efficiency Characterization for Specific Storage Estimation

“…Assessments of aquifer confinement status (in order to ensure semi-confined or confined conditions) when using time series methods have also been limited (e.g., Rahi and Halihan 2013;Acworth et al 2015;Dong et al 2015). Confined aquifer Robinson and Bell (1971) Appalachian Mountains, USA LR Rhoads and Robinson (1979) Virginia, USA GR, LR, DMA Galloway and Rojstaczer (1988) Yucca Mountain, Nevada, USA Q&R Robson and Banta (1990) Colorado, USA CLK Beavan et al (1991) Aswan, Egypt Unclear Geldon et al (1997) Yucca Mountain, Nevada, USA LR Rasmussen and Crawford (1997) Savannah River Site, USA LR, D&R, R&C Seo (1999) Iowa, USA LR, NM Hobbs and Fourie (2000) Vaal River Barrage, South Africa LR Sahu (2004) Ohio, USA LR Rasmussen and Mote (2007) Savannah River Site, USA LR, R&C Rahi and Halihan (2009) Oklahoma, USA RAH Butler et al (2011) Kansas, USA R&C Darner and Sheets (2012) Great Lakes Region, USA CLK Hussein et al (2013) East Yorkshire, UK Q&R Odling et al (2015) East Yorkshire, UK Q&R, AM, NM Augustine (2015) Alberta, Canada LR, CLK, RAH, GR, R&C Dong et al (2015) Kyushu, Japan CLK Fuentes-Arreazola et al (2018) Baja California Peninsula, Mexico RAH Acworth and Brain (2008) New South Wales, Australia A&B, GR Acworth et al (2015) New South Wales, Australia A&B Acworth et al (2016) New South Wales, Australia ACW Acworth et al (2017) New South Wales, Australia ACW Turnadge et al (this article) Western Australia, Australia AoR, MoR, LR, CLK, RAH, Q&R, ACW, R&C Unconfined aquifer Hare and Morse (1997) New York State, USA LR Hare and Morse (1999) New York State, USA LR Barr et al (2000) Saskatchewan, Canada BAR Lee and Lee (2000) Wonju, South Korea Q&R, CLK Spane a...…”