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Journal ArticleDOI

Measuring Soil Water Content with Ground Penetrating Radar

01 Nov 2003-Vadose Zone Journal (Soil Science Society)-Vol. 2, Iss: 4, pp 476-491
TL;DR: In this paper, a comprehensive review of methods to measure soil water content with ground penetrating radar (GPR) is presented, which distinguishes four methodologies: reflected wave velocity, ground wave velocity and surface reflection coefficient.
Abstract: We present a comprehensive review of methods to measure soil water content with ground penetrating radar (GPR). We distinguish four methodologies: soil water content determined from reflected wave velocity, soil water content determined from ground wave velocity, soil water content determined from transmitted wave velocity between boreholes, and soil water content determined from the surface reflection coefficient. For each of these four methodologies, we discuss the basic principles, illustrate the quality of the data with field examples, discuss the possibilities and limitations, and identify areas where future research is required. We hope that this review will further stimulate the community to consider ground penetrating radar as one of the possible tools to measure soil water content.
Citations
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Journal ArticleDOI
TL;DR: In this article, the authors review advances in sensor technology, particularly emerging geophysical methods and distributed sensors, aimed at bridging this gap and offer a vision for future research, listing many of the current scientific and technical challenges.
Abstract: At the watershed scale, soil moisture is the major control for rainfall–runoff response, especially where saturation excess runoff processes dominate. From the ecological point of view, the pools of soil moisture are fundamental ecosystem resources providing the transpirable water for plants. In drylands particularly, soil moisture is one of the major controls on the structure, function, and diversity in ecosystems. In terms of the global hydrological cycle, the overall quantity of soil moisture is small, ∼0.05%; however, its importance to the global energy balance and the distribution of precipitation far outweighs its physical amount. In soils it governs microbial activity that affects important biogeochemical processes such as nitrification and CO2 production via respiration. During the past 20 years, technology has advanced considerably, with the development of different electrical sensors for determining soil moisture at a point. However, modeling of watersheds requires areal averages. As a result, point measurements and modeling grid cell data requirements are generally incommensurate. We review advances in sensor technology, particularly emerging geophysical methods and distributed sensors, aimed at bridging this gap. We consider some of the data analysis methods for upscaling from a point to give an areal average. Finally, we conclude by offering a vision for future research, listing many of the current scientific and technical challenges.

877 citations


Cites background or methods from "Measuring Soil Water Content with G..."

  • ...One relatively simple application of GPR for θ is measuring the travel time of the direct ground wave, which travels from the source to receiver antenna through the topmost layer of the soil (Huisman et al., 2003b; Hubbard et al., 2002)....

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  • ...Th e most comprehensive studies of measurement error for θ are presented in Huisman et al. (2003b, 2001, 2002)....

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  • ...…is transforming the determined dielectric constant κ to an estimate of θ. Calibration can be obtained at a fi eld site using other forms of data, such as a neutron probe or TDR (Huisman et al., 2003b), but heterogeneity below the scale of the measurement has a large impact on the κ−θ relationship....

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  • ...…that measure ground electrical conductivity, which includes DC resistivity (Samouelian et al., 2005) and EMI (Sheets and Hendrickx, 1995), and (ii) those measuring electromagnetic wave propagation time through the ground, such as ground penetrating radar (GPR) (Knight, 2001; Huisman et al., 2003a)....

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  • ...A variety of methods have been adopted to determine θ from GPR data and have been reviewed in Huisman et al. (2003a) and Annan (2005a,b)....

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Journal ArticleDOI
TL;DR: The Prediction in Ungauged Basins (PUB) initiative of the International Association of Hydrological Sciences (IAHS) launched in 2003 and concluded by the PUB Symposium 2012 held in Delft (23-25 October 2012), set out to shift the scientific culture of hydrology towards improved scientific understanding of hydrological processes, as well as associated uncertainties and the development of models with increasing realism and predictive power as discussed by the authors.
Abstract: The Prediction in Ungauged Basins (PUB) initiative of the International Association of Hydrological Sciences (IAHS), launched in 2003 and concluded by the PUB Symposium 2012 held in Delft (23–25 October 2012), set out to shift the scientific culture of hydrology towards improved scientific understanding of hydrological processes, as well as associated uncertainties and the development of models with increasing realism and predictive power. This paper reviews the work that has been done under the six science themes of the PUB Decade and outlines the challenges ahead for the hydrological sciences community.Editor D. KoutsoyiannisCitation Hrachowitz, M., Savenije, H.H.G., Bloschl, G., McDonnell, J.J., Sivapalan, M., Pomeroy, J.W., Arheimer, B., Blume, T., Clark, M.P., Ehret, U., Fenicia, F., Freer, J.E., Gelfan, A., Gupta, H.V., Hughes, D.A., Hut, R.W., Montanari, A., Pande, S., Tetzlaff, D., Troch, P.A., Uhlenbrook, S., Wagener, T., Winsemius, H.C., Woods, R.A., Zehe, E., and Cudennec, C., 2013. A d...

848 citations


Cites methods from "Measuring Soil Water Content with G..."

  • ...While the methods and protocols for ground-penetrating radar soil moisture estimation are comparatively well developed (e.g. Huisman et al. 2003, Lunt et al. 2005), the utility of electrical resistivity surveys for soil moisture estimation (e.g. Samouëlian et al. 2005) is still limited due to…...

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Journal ArticleDOI
TL;DR: In this article, the authors highlight and review the state of the art in using soil moisture measurements for estimation of soil hydraulic properties, quantification of water and energy fluxes, and retrieval of spatial and temporal dynamics of soil moisture profiles.
Abstract: [1] We explore and review the value of soil moisture measurements in vadose zone hydrology with a focus on the field and catchment scales This review is motivated by the increasing ability to measure soil moisture with unprecedented spatial and temporal resolution across scales We highlight and review the state of the art in using soil moisture measurements for (1) estimation of soil hydraulic properties, (2) quantification of water and energy fluxes, and (3) retrieval of spatial and temporal dynamics of soil moisture profiles We argue for the urgent need to have access to field monitoring sites and databases that include detailed information about variability of hydrological fluxes and parameters, including their upscaled values In addition, improved data assimilation methods are needed that fully exploit the information contained in soil moisture data The development of novel upscaling methods for predicting effective moisture fluxes and disaggregation schemes toward integrating large-scale soil moisture measurements in hydrological models will increase the value of soil moisture measurements Finally, we recognize a need to develop strategies that combine hydrogeophysical measurement techniques with remote sensing methods

647 citations


Cites background from "Measuring Soil Water Content with G..."

  • ...The most prominent examples are offground ground penetrating radar [e.g., Huisman et al., 2003; Serbin and Or, 2004, 2005; Lambot et al., 2006a, 2006b] and electromagnetic induction [e.g., Sheets and Hendrickx, 1995; Akbar et al., 2005; Corwin and Lesch, 2005]....

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Journal ArticleDOI
TL;DR: In this paper, the authors present a review of on-the-go soil sensors based on electrical and electromagnetic, optical and radiometric, mechanical, acoustic, pneumatic, and electrochemical measurement concepts.

596 citations

Journal ArticleDOI
TL;DR: Key challenges in modeling soil processes are identified, including the systematic incorporation of heterogeneity and uncertainty, the integration of data and models, and strategies for effective integration of knowledge on physical, chemical, and biological soil processes.
Abstract: The remarkable complexity of soil and its importance to a wide range of ecosystem services presents major challenges to the modeling of soil processes. Although major progress in soil models has occurred in the last decades, models of soil processes remain disjointed between disciplines or ecosystem services, with considerable uncertainty remaining in the quality of predictions and several challenges that remain yet to be addressed. First, there is a need to improve exchange of knowledge and experience among the different disciplines in soil science and to reach out to other Earth science communities. Second, the community needs to develop a new generation of soil models based on a systemic approach comprising relevant physical, chemical, and biological processes to address critical knowledge gaps in our understanding of soil processes and their interactions. Overcoming these challenges will facilitate exchanges between soil modeling and climate, plant, and social science modeling communities. It will allow us to contribute to preserve and improve our assessment of ecosystem services and advance our understanding of climate-change feedback mechanisms, among others, thereby facilitating and strengthening communication among scientific disciplines and society. We review the role of modeling soil processes in quantifying key soil processes that shape ecosystem services, with a focus on provisioning and regulating services. We then identify key challenges in modeling soil processes, including the systematic incorporation of heterogeneity and uncertainty, the integration of data and models, and strategies for effective integration of knowledge on physical, chemical, and biological soil processes. We discuss how the soil modeling community could best interface with modern modeling activities in other disciplines, such as climate, ecology, and plant research, and how to weave novel observation and measurement techniques into soil models. We propose the establishment of an international soil modeling consortium to coherently advance soil modeling activities and foster communication with other Earth science disciplines. Such a consortium should promote soil modeling platforms and data repository for model development, calibration and intercomparison essential for addressing contemporary challenges.

542 citations


Cites background from "Measuring Soil Water Content with G..."

  • ...…(Weller et al., 2007; Saey et al., 2009; Rudolph et al., 2015), spectral-induced polarization (Slater et al., 2006), ground-penetrating radar (Huisman et al., 2003; Lambot et al., 2010), and gamma-ray spectroscopy (Rossel and McBratney, 1998; Rawlins et al., 2007) field NIR spectroscopy…...

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References
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Journal ArticleDOI
TL;DR: The dependence of the dielectric constant, at frequencies between 1 MHz and 1 GHz, on the volumetric water content is determined empirically in the laboratory as discussed by the authors, and the effect of varying the texture, bulk density, temperature, and soluble salt content on this relationship was also determined.
Abstract: The dependence of the dielectric constant, at frequencies between 1 MHz and 1 GHz, on the volumetric water content is determined empirically in the laboratory. The effect of varying the texture, bulk density, temperature, and soluble salt content on this relationship was also determined. Time-domain reflectometry (TDR) was used to measure the dielectric constant of a wide range of granular specimens placed in a coaxial transmission line. The water or salt solution was cycled continuously to or from the specimen, with minimal disturbance, through porous disks placed along the sides of the coaxial tube. Four mineral soils with a range of texture from sandy loam to clay were tested. An empirical relationship between the apparent dielectric constant Ka and the volumetric water content θv, which is independent of soil type, soil density, soil temperature, and soluble salt content, can be used to determine θv, from air dry to water saturated, with an error of estimate of 0.013. Precision of θv to within ±0.01 from Ka can be obtained with a calibration for the particular granular material of interest. An organic soil, vermiculite, and two sizes of glass beads were also tested successfully. The empirical relationship determined here agrees very well with other experimenters' results, which use a wide range of electrical techniques over the frequency range of 20 MHz and 1 GHz and widely varying soil types. The results of applying the TDR technique on parallel transmission lines in the field to measure θv versus depth are encouraging.

4,855 citations


"Measuring Soil Water Content with G..." refers background or methods in this paper

  • ...However, evenpermittivity, ε, and volumetric soil water content, (m3 m 3), when using published petrophysical relationships derived withwas proposed by Topp et al. (1980): TDR (such as Eq....

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  • ...A well-established in situ electromagnetic technique for soil water content investigations is time domain re- with the loss tangent defined as flectometry (TDR), which was introduced in vadose zone hydrology in the early 1980s (Topp et al., 1980)....

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Journal ArticleDOI
TL;DR: In this article, the basic principles and practices involved in acquiring high-quality radar data in the field are illustrated by selected case histories, showing how radar has been used to map the bedrock and delineate soil horizons to a depth of more than 20 m.
Abstract: Ground-penetrating radar is a technique which offers a new way of viewing shallow soil and rock conditions. The need to better understanding overburden conditions for activities such as geochemical sampling, geotechnical investigations, and placer exploration, as well as the factors controlling groundwater flow, has generated an increasing demand for techniques which can image the subsurface with higher resolution than previously possible. The areas of application for ground-penetrating radar are diverse. The method has been used successfully to map ice thickness, water depth in lakes, bedrock depth, soil stratigraphy, and water table depth. It is also used to delineate rock fabric, detect voids and identify karst features. The effective application of the radar for the high-resolution definition of soil stratigraphy and fractures in bedrock is highlighted. The basic principles and practices involved in acquiring high quality radar data in the field are illustrated by selected case histories. One example demonstrates how radar has been used to map the bedrock and delineate soil horizons to a depth of more than 20 m. Two case histories show how radar has been used to map fractures and changes of rock type to 40 m range from inside a mine. Another case history demonstrates how radar has also been used to detect and map the extent of groundwater contamination. The corroboration of the radar results by borehole investigations demonstrates the power and utility of the high-resolution radar method as an aid for interpolation and extrapolation of the information obtained with conventional coring programmes. With the advent of new instrumentation and field procedures, the routine application of the radar method is becoming economically viable and the method will see expanded use in the future.

1,962 citations


"Measuring Soil Water Content with G..." refers background or methods in this paper

  • ...The average velocity between the ground surfacecenter frequency, the resolution of GPR increases with inand the anomaly, vsoil, can be determined from a GPR transectcreasing center frequency (Davis and Annan, 1989)....

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  • ...The firstlent introduction to GPR in hydrogeological applications is class contains the methods that use a single antenna separationavailable in Davis and Annan (1989). for soil water content estimation (e.g., soil water content esti-The GPR technique is similar in principle to seismic and mation…...

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Journal ArticleDOI
TL;DR: In this paper, the authors evaluated the microwave dielectric behavior of soil-water mixtures as a function of water content and soil textural composition for the 1.4-to 18-GHz region.
Abstract: This paper is the second in a series evaluating the microwave dielectric behavior of soil-water mixtures as a function of water content and soil textural composition. Part II draws upon the data presented in Part 1 [13] to develop appropriate empirical and theoretical dielectric mixing models for the 1.4-to 18-GHz region. A semiempirical mixing model based upon the index of refraction is presented, requiring only easily ascertained soil physical parameters such as volumetric moisture and soil textural composition as inputs. In addition, a theoretical model accounting explicitly for the presence of a hydration layer of bound water adjacent to hydrophilic soil particle surfaces is presented. A four-component dielectric mixing model treats the soil-water system as a host medium of dry soil solids containing randomly distributed and randomly oriented disc-shaped inclusions of bound water, bulk water, and air. The bulk water component is considered to be dependent upon frequency, temperature, and salinity. The soil solution is differentiated by means of a soil physical model into 1) a bound component and 2) a bulk soil solution. The performance of each model is evaluated as a function of soil moisture, soil texture, and frequency, using the dielectric measurements of five soils ranging from sandy loam to silty clay (as presented in Part I [13]) at frequencies between 1.4 and 18 GHz. The semiempirical mixing model yields an excellent fit to the measured data at frequencies above 4 GHz. At 1.

1,805 citations

Journal ArticleDOI
TL;DR: In this paper, a simple but accurate formula is developed for the quick calculation of interval velocities from the known x2-T2 technique, which is obtained through a correlation of velocity with rock type and depth.
Abstract: The purpose of this paper is to discuss field and interpretive techniques which permit, in favorable cases, the quite accurate determination of seismic interval velocities prior to drilling. A simple but accurate formula is developed for the quick calculation of interval velocities from “average velocities” determined by the known x2-T2 technique. To secure accuracy a careful study of multiple reflections is necessary and this is discussed. Although the principal objective in determining velocities is to allow an accurate structural interpretation to be made from seismic reflection data, an important secondary objective is to get some lithological information. This is obtained through a correlation of velocities with rock type and depth.

1,232 citations


"Measuring Soil Water Content with G..." refers methods in this paper

  • ...To convert these average velocities to interval velocities of each layer, vint,n, the Dix formula (Dix, 1955; Yilmaz, 1987) can be used: vint,n trw,nv 2 soil,n trw,n 1v2soil,n 1 trw,n trw,n 1 [16] where vsoil,n is the average velocity from the surface down to the bottom of layer n, vsoil,n 1 is the…...

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Journal ArticleDOI
TL;DR: In this paper, a calibration curve for the TDR method is presented which is not restricted to specific soil conditions, based on the dielectric mixing model of Dobson et al. (1985).
Abstract: Time domain reflectometry (TDR) has been developed to an operational level for the measurement of soil water content during the past decade. Because it is able to provide fast, precise and nondestructive in situ measurements, it has become an alternative to the neutron scattering method, in particular for monitoring water content under field conditions. One of the major disadvantages of the neutron scattering technique is that, due to the relatively high sensitivity of the signal to factors other than water content, site-specific calibration is usually required. In this paper a calibration curve for the TDR method is presented which is not restricted to specific soil conditions. The calibration is based on the dielectric mixing model of Dobson et al. (1985). Measurements of volumetric water content and dielectric number at eleven different field sites representing a wide range of soil types were used to determine the parameter of the model by weighted nonlinear regression. The uncertainty (root mean square error) of water content values calculated with the optimized calibration curve was estimated not to exceed 0.013 cm3/cm3. This value is comparable to the precision of the thermogravimetric method. From a sensitivity analysis it was determined that the temperature dependence of the TDR signal may have to be corrected to obtain optimum accuracy.

895 citations


"Measuring Soil Water Content with G..." refers methods in this paper

  • ...[4]Furthermore, recent improvements in GPR technology and ε is based on dielectric mixing models, which use the volume fractions and the dielectric permittivity of each soil constituent to derive a relationship (e.g., Dobson et al., 1985; Roth et al., 1990; Friedman, 1998; Jones and Friedman, 2000)....

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  • ...and ε is based on dielectric mixing models, which use the volume fractions and the dielectric permittivity of each soil constituent to derive a relationship (e.g., Dobson et al., 1985; Roth et al., 1990; Friedman, 1998; Jones and Friedman, 2000)....

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