Influence of soil consolidation and thermal expansion effects on height and gravity variations

Romagnoli, Claudia; Zerbini, Susanna; Lago, L.; Richter, Bernd; Simon, D.; Domenichini, F.; Elmi, Carlo; Ghirotti, Monica

doi:10.1016/s0264-3707(03)00012-7

Cited by 46 publications

(45 citation statements)

References 6 publications

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“…[26] Soil expansion or compaction between gravity surveys can potentially alter the ground surface elevation, resulting in a change in gravity between surveys that is not associated with groundwater mass changes [Romagnoli et al, 2003]. Soil expansion data were not available for this survey.…”

Section: Gravity Data Processingmentioning

confidence: 99%

Estimating specific yield and storage change in an unconfined aquifer using temporal gravity surveys

Gehman

Harry

Sanford

et al. 2009

Water Resources Research

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[1] Two high-precision gravity surveys were conducted to determine groundwater mass changes at a managed groundwater recharge site in northeastern Colorado. Gravity data were collected during pumping and two months after pumping ceased. During pumping, gravity was lower by as much as 46 mGal near the pumping wells and higher by as much as 90 mGal near the recharge ponds in comparison to data collected after pumping had ceased. These differences are attributed to changes in groundwater mass associated with drawdown and infiltration. Inverse modeling of the gravity data indicates a 5.1 Â 10 5 m 3 decrease in storage beneath the recharge ponds between the two surveys, which we attribute to dissipation of the groundwater mound created by recharge during pumping. This estimate of the change in groundwater storage is made independently of assumptions of physical properties of the aquifer. Dividing the change in water volume per unit area determined from the gravity modeling by the change in water level measured in wells provides an estimate of specific yield (S y ) of 0.21 ± 0.03, which is within the range of specific yield estimates derived from aquifer tests at the site. Water level changes predicted from the gravity data agree on average to within ±0.45 m of those measured, which we take to be an estimate of the uncertainty in water table depth predictions that can be obtained from gravimetric data in unconfined aquifers. The study covers a 3.2 km 2 area, providing a prototype for similar studies at larger scales.

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Section: Gravity Data Processingmentioning

confidence: 99%

Estimating specific yield and storage change in an unconfined aquifer using temporal gravity surveys

Gehman

Harry

Sanford

et al. 2009

Water Resources Research

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“…Although the causes are not yet completely understood, the most likely explanations are a combination of atmospheric loading (e.g., van Dam et al, 1997), hydrological loading (e.g., van Dam et al, 2001), and thermal expansion of the GPS stations (e.g., Romagnoli et al, 2003). Blewitt and Lavallée (2002) demonstrated that an annual signal within the data deteriorates the accuracy of the estimated linear trend in time-series with an observation time span of a few years, even when this annual signal is taken into account during the estimation process.…”

Section: Introductionmentioning

confidence: 99%

The influence of seasonal signals on the estimation of the tectonic motion in short continuous GPS time-series

Bos

Bastos

Fernandes

2010

Journal of Geodynamics

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Please cite this article as: Bos, M.S., Bastos, L., Fernandes, R.M.S., The influence of seasonal signals on the estimation of the tectonic motion in short continuous GPS time-series, Journal of Geodynamics (2008Geodynamics ( ), doi:10.1016Geodynamics ( /j.jog.2009 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Page 1 of 19A c c e p t e d M a n u s c r i p t However, Blewitt and Lavallée (2002) showed that including an annual signal in the estimation process still can give a larger linear trend error than the trend error estimated from data from which the annual signal has been removed by other means. They assumed that the GPS data only contained white noise and we extend their result to the case of power-law plus white noise which is known to exist in most GPS observations. For the GPS stations CASC, LAGO, PDEL and TETN the difference in trend error between having or not having an annual signal in the data is around ten times larger when a power-law plus white noise model is used instead of a pure white noise model. A c c e p t e d M a n u s c r i p t Next, our methodology can be used to estimate for any station how much the accuracy of the linear trend will improve when one tries to subtract the annual signal from the GPS time-series by using a physical model.Finally, we demonstrate that for short time-series the trend error is more influenced by the fact that the noise properties also need to be estimated from the data. This causes on average an underestimation of the trend error.

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“…Monument wander could be the result of factors such as long-term weathering of rock and soil local to the monument [Langbein and Johnson, 1997], while the seasonal component is usually related to changes in groundwater [e.g., Langbein et al, 1990;Bawden et al, 2001;Finnegan et al, 2008] and/or temperature [e.g., Dong et al, 2002;Romagnoli et al, 2003].…”

Section: Introductionmentioning

confidence: 99%

Characterization of site‐specific GPS errors using a short‐baseline network of braced monuments at Yucca Mountain, southern Nevada

et al. 2009

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[1] We use a short-baseline network of braced monuments to investigate site-specific GPS effects. The network has baseline lengths of $10, 100, and 1000 m. Baseline time series have root mean square (RMS) residuals, about a model for the seasonal cycle, of 0.05-0.24 mm for the horizontal components and 0.20-0.72 mm for the radial. Seasonal cycles occur, with amplitudes of 0.04-0.60 mm, even for the horizontal components and even for the shortest baselines. For many time series these lag seasonal cycles in local temperature measurements by 23-43 days. This could suggest that they are related to bedrock thermal expansion. Both shorter-period signals and seasonal cycles for shorter baselines to REP2, the one short-braced monument in our network, are correlated with temperature, with no lag time. Differences between REP2 and the other stations, which are deep-braced, should reflect processes occurring in the upper few meters of the ground. These correlations may be related to thermal expansion of these upper ground layers, and/or thermal expansion of the monuments themselves. Even over these short distances we see a systematic increase in RMS values with increasing baseline length. This, and the low RMS levels, suggests that site-specific effects are unlikely to be the limiting factor in the use of similar GPS sites for geophysical investigations.

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Influence of soil consolidation and thermal expansion effects on height and gravity variations

Cited by 46 publications

References 6 publications

Estimating specific yield and storage change in an unconfined aquifer using temporal gravity surveys

Estimating specific yield and storage change in an unconfined aquifer using temporal gravity surveys

The influence of seasonal signals on the estimation of the tectonic motion in short continuous GPS time-series

Characterization of site‐specific GPS errors using a short‐baseline network of braced monuments at Yucca Mountain, southern Nevada

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