Simulation of vadose zone flow processes via inverse modeling of modified multistep outflow for fine‐grained soils

Bahrami, Amir; Aghamir, Fateme

doi:10.1002/saj2.20112

Cited by 3 publications

(2 citation statements)

References 33 publications

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“…This inversion‐based parameter estimation can be either deterministic (Šimůnek & van Genuchten, 1997) or stochastic (Thoma et al., 2014). Compared with steady‐state tests, transient tests reduce the measurement time significantly, and thus they have been increasingly adopted in practice to determine the unsaturated hydraulic properties of various soils (Bahrami & Aghamir, 2020; Elliott & Price, 2020).…”

Section: Introductionmentioning

confidence: 99%

Coupled inversion of hydraulic and self‐potential data from transient outflow experiments to estimate soil petrophysical properties

Xie

Cui

Niu

2021

Vadose Zone Journal

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Hydraulicproperties of soils could play an important role in affecting the partitioning of precipitation in the critical zone. In addition to traditional approaches, in the last two decades, many geophysical methods have been used to aid the hydrologic characterization and measurement of geological materials. In particular, the self-potential (SP) method shows great potential in these hydrogeophysical applications. The objective of this study is to evaluate whether the addition of SP data can improve the estimation of hydraulic properties of soils in an outflow experiment. A stochastic, coupled hydrogeophysical inversion was developed, in which the governing equations were solved using the finite volume method and the parameter estimation was conducted using a Bayesian approach associated with the Markov chain Monte Carlo technique. The results show that the addition of SP data in the inversion could reduce the uncertainty related to the estimated hydraulic parameters of soils and the length of the associated 95% confidence interval can be shortened by ∼1/3. It is also shown that the electrical properties of soils at saturated and unsaturated conditions may also be estimated from the outflow experiment when SP data are available. Compared with hydraulic parameters, the accuracy of the estimated electrical properties is slightly lower. Among them, the saturated streaming potential coupling coefficient C sat has the highest accuracy and lowest uncertainty since C sat directly influences the magnitude of SP signals. The accuracy of other electrical parameters is lower than that of C sat (and hydraulic parameters), and the associated uncertainty can be one order of magnitude larger.

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Section: Introductionmentioning

confidence: 99%

Coupled inversion of hydraulic and self‐potential data from transient outflow experiments to estimate soil petrophysical properties

Xie

Cui

Niu

2021

Vadose Zone Journal

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“…The RMSE determines the spread of the error distribution, while MEE shows the overall overestimation or underestimation of the model. The MAX E and MIN E metrics are used to show the largest positive and negative errors, respectively (Bahrami & Aghamir, 2020; Bahrami et al, 2020; Moriasi et al, 2015). An NSE comprises in [−∞, 1] where an NSE value equal to unity shows a perfect match, and an NSE value equal to zero means that the average of observed values is as good as estimated values.…”

Section: Methodsmentioning

confidence: 99%

Recalibration of existing pedotransfer functions to estimate soil bulk density at a regional scale

Khodaverdiloo

Bahrami

Rahmati

et al. 2022

European J Soil Science

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Soil bulk density (ρ b ) is an important indicator of soil quality, productivity, compaction and porosity. Despite its importance, ρ b is often omitted from global datasets due to the costs of making many direct ρ b measurements and the difficulty of direct measurement on rocky, sandy, very dry, or very wet soils. Pedotransfer functions (PTFs) are deployed to address these limitations. Using readily available soil properties, PTFs employ estimator equations to fit existing datasets to estimate properties like ρ b . However, PTF performance often declines when applied to soils outside those in the training dataset.Potentially, recalibrating existing PTFs using new observations would leverage the power of large datasets used in the original PTF derivation, while updating information based on new soil observations. Here, we evaluate such a recalibration approach for ρ b estimation, benchmarking its performance against two alternatives: the original, uncalibrated PTFs, and novel, local PTFs derived solely from new soil observations. Using a ρ b dataset of N = 360 total observations obtained in West Azerbaijan, Iran, we varied the local dataset size (with N = 15, 30, 60, and 360) and recalibrated four existing PTFs with these data.Local PTFs were generated based on stepwise multiple linear regression for the same datasets. The same PTFs (original, recalibrated, and local) were also applied to the study area, and the resulting ρ b estimates were compared with the global SoilGrids dataset. Recalibration of PTFs reduced errors relative to the original uncalibrated PTFs; for instance, the NSE increased from À22.07 to 0.30 (uncalibrated) to 0.20-0.41 (recalibrated), and RMSE decreased from 0.12 to 0.60 Mg m À3 (uncalibrated) to 0.10-0.13 Mg m À3 (recalibrated). The recalibrated PTFs performance was comparable to or better than local PTFs applied to the same data. Recalibration of existing PTFs with local/regional uses provides a viable alternative to the use of global datasets or the development of local PTFs in data-scarce regions. Highlights• Existing global PTFs were calibrated and tested using a small dataset for local utilisation.• Several new local PTFs were also developed using the same datasets.

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Studying sand component of soil texture using the spectroscopic method

Bahrami

Danesh

Bahrami

2022

Infrared Physics & Technology

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Simulation of vadose zone flow processes via inverse modeling of modified multistep outflow for fine‐grained soils

Cited by 3 publications

References 33 publications

Coupled inversion of hydraulic and self‐potential data from transient outflow experiments to estimate soil petrophysical properties

Coupled inversion of hydraulic and self‐potential data from transient outflow experiments to estimate soil petrophysical properties

Recalibration of existing pedotransfer functions to estimate soil bulk density at a regional scale

Studying sand component of soil texture using the spectroscopic method

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