scholarly journals ESTIMATES OF SOIL WATER CONTENT USING GROUND PENETRATING RADAR IN FIELD CONDITIONS

2015 ◽  
Vol 33 (3) ◽  
pp. 389 ◽  
Author(s):  
Marcelo Jorge Luz Mesquita ◽  
José Gouvêa Luiz ◽  
José de Paulo Rocha da Costa
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Wave Velocity ◽  
Ground Penetrating Radar ◽  
Time Domain Reflectometry ◽  
Field Conditions ◽  
Calibration Equation ◽  
Ground Penetrating

ABSTRACT. Electromagnetic methods play an important role in the study of soil water content, mainly because electromagnetic properties in the shallow subsurface area are primarily controlled by the presence of water. This work analyzes the effectiveness of Ground Penetrating Radar (GPR) as a tool for estimating soil water content in field conditions, introduces a calibration equation to estimate average soil moisture of the area studied from the analysis of GPR wave velocity, and evaluates the process used to create it. Methodologies for collecting GPR data seeking the determination of soil moisture from the velocity of the electromagnetic wave and the use of equations proposed in the literature, Topp and Roth, are also discussed. The GPR common-offset methodology (400 MHz antennas) was utilized in a study in Cuiarana, Salin´opolis, Par´a State, in northern Brazil and the resulting data compared with data from TDR (Time Domain Reflectometry) (0.12 m double probe) methodology. The data were then statistically analyzed enabling the establishment of a calibration equation for water content determination in terms of electromagnetic wavevelocity obtained with GPR. The study successfully showed the feasibility and limitations of estimating water content using GPR. Also is discussed the possibility of calibration equation to the soil water content analysis with GPR data using, as parameter, data obtained by other indirect method, in this case, the TDR.Keywords: soil water content, relative permittivity, GPR, TDR, wave velocity. RESUMO. Os métodos eletromagnéticos são uma importante ferramenta no estudo da umidade do solo, principalmente porque as propriedades eletromagnéticas da subsuperfície rasa são controladas pela presença de água. Este trabalho, além de analisar a eficácia do Radar de Penetração no Solo (GPR) como ferramenta de medição da umidade do solo in situ sob condições de campo não controladas, introduz uma equação de calibração para estimar a umidade do solo da área estudada a partir da análise da velocidade da onda do GPR e avalia o processo da sua criação. São também discutidas as metodologias comumente empregadas na coleta de dados com o GPR, visando a determinação da umidade do solo a partir da velocidade da onda eletromagnética, assim como a utilização das equações propostas na literatura, Topp e Roth. A metodologia common-offset (GPR com antenas de 400 MHz) foi empregada em um estudo realizado em Cuiarana, município de Salinópolis, Pará, no norte do Brasil e os dados comparados com medidas de umidade realizadas com TDR (sonda dupla de 0,12 m). Os dados foram estatisticamente correlacionados permitindo o estabelecimento de uma equação de calibração para a determinação de umidade em termos da velocidade da onda eletromagnética obtida com o GPR. O estudo demonstrou com sucesso a viabilidade, a rapidez e as limitações do GPR na estimativa do conteúdo de água no solo. Também é discutida a possibilidade da calibração de equação para análise de umidade com o GPR usando como parâmetro dados obtidos por outro método indireto, neste caso, o TDR.Palavras-chave: umidade do solo, permissividade relativa, GPR, TDR, velocidade da onda.

scholarly journals Application of Ground-Penetrating Radar and a Combined Penetrometer–Moisture Probe for Evaluating Spatial Distribution of Soil Moisture and Soil Hardness in Coastal and Inland Windbreaks

Geosciences ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 238
Author(s):  
Kenta Iwasaki ◽  
Makoto Tamura ◽  
Hirokazu Sato ◽  
Kazuhiko Masaka ◽  
Daisuke Oka ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Soil Moisture ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Ground Penetrating Radar ◽  
Soil Compaction ◽  
Soil Moisture Condition ◽  
Soil Hardness ◽  
Ground Penetrating

The development of a method to easily investigate the spatial distribution of soil moisture and soil hardness in tree windbreaks is necessary because these windbreaks often decline due to inappropriate soil moisture condition and soil compaction. This research examined the applicability of ground-penetrating radar (GPR) and a combined penetrometer–moisture probe (CPMP) for evaluating the spatial distribution of soil moisture and soil hardness in four windbreaks with different soil characteristics. A GPR-reflecting interface was observed at a less permeable layer in a coastal windbreak and at a depth affected by soil compaction in an inland windbreak with andosol. The spatial distribution of the groundwater table could also be evaluated by examining the attenuation of GPR reflection in a coastal windbreak. In contrast, GPR was not applicable in an inland windbreak with peat because of high soil water content near the soil surface. The CPMP could detect vertical distributions of soil hardness and soil water content regardless of soil type. The CPMP was useful for interpreting GPR profiles, and GPR was useful for interpolating the information about the horizontal distribution of soil moisture and soil hardness between survey points made with the CPMP. Thus, the combination of GPR and a CPMP is ideal for examining the two-dimensional spatial distribution of soil moisture and soil hardness at windbreaks with soils for which both methods are applicable.

ESTIMATES OF SOIL WATER CONTENT USING GROUND-PENETRATING RADAR IN FIELD CONDITIONS

2016 ◽  
Vol 33 (3) ◽  
Author(s):  
Marcelo Jorge Luz Mesquita ◽  
José Gouvêa Luiz ◽  
José de Paulo Rocha da Costa
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Ground Penetrating Radar ◽  
Field Conditions ◽  
Electromagnetic Properties ◽  
Shallow Subsurface ◽  
Electromagnetic Methods ◽  
Ground Penetrating

ABSTRACT. Electromagnetic methods play an important role in the study of soil water content, mainly because electromagnetic properties in the shallow subsurface area are primarily controlled by the presence of... RESUMO. Os métodos eletromagnéticos são uma importante ferramenta no estudo da umidade do solo, principalmente porque as propriedades eletromagnéticas da subsuperfície rasa são...

Coupling of dielectric mixing models with full-wave ground-penetrating radar signal inversion for sandy-soil-moisture estimation

Geophysics ◽  
2012 ◽  
Vol 77 (3) ◽  
pp. H33-H44 ◽  
Author(s):  
Anh Phuong Tran ◽  
Mohammad Reza Mahmoudzadeh Ardekani ◽  
Sébastien Lambot
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Sandy Soil ◽  
Ground Penetrating Radar ◽  
Mixing Models ◽  
Apparent Conductivity ◽  
Full Wave ◽  
Ground Penetrating

We coupled dielectric mixing models with a full-wave ground-penetrating-radar (GPR) model to estimate the soil water content by inversion. Two mixing models were taken into account in this study, namely, a power law model and the Wang and Schmugge model. With this combination, we could account for the frequency dependence of the dielectric permittivity and apparent conductivity in the inverse algorithm and directly estimate the soil water content without using an empirical petrophysical formula or a priori knowledge on soil porosity. The approach was validated by a series of experiments with sandy soil in controlled laboratory conditions. The results showed that the performance of our approach is better than the common approach, which assumes a linear dependence of apparent conductivity on frequency and uses Topp’s equation to transform permittivity to water content. GPR data were perfectly reproduced in the time and frequency domains, leading to very accurate water-content estimates with an average absolute error of less than [Formula: see text]. However, the accuracy was reduced as the water content increased. Sensitivity analysis indicated that the Green’s function was most sensitive to the water content and sand-layer thickness but much less so with DC conductivity. The results also revealed that as the frequency increased, although the permittivity was nearly constant, the apparent electrical conductivity and the attenuation increased remarkably, especially for wet sands due to dielectric losses. The successful validation of the proposed approach opens a promising avenue of development to use dielectric mixing models for soil-moisture mapping from GPR measurements.

Precision and accuracy of three alternative instruments for measuring soil water content in two forest soils of the Pacific Northwest

2005 ◽  
Vol 35 (8) ◽  
pp. 1867-1876 ◽  
Author(s):  
Nicole M Czarnomski ◽  
Georgianne W Moore ◽  
Tom G Pypker ◽  
Julian Licata ◽  
Barbara J Bond
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Pacific Northwest ◽  
Lower Cost ◽  
Time Domain Reflectometry ◽  
Calibration Equation ◽  
Accuracy And Precision ◽  
The Pacific

We compared the accuracy and precision of three devices for measuring soil water content in both natural and repacked soils and evaluated their temperature sensitivity. Calibrations were developed for a capacitance instrument (ECH2O), a time domain reflectometry cable tester (CT), and a water content reflectometer (WCR) in soils collected from the Wind River and H.J. Andrews Experimental Forests. We compared these calibrations with equations suggested by manufacturers or commonly used in the literature and found the standard equations predicted soil moisture content 0%–11.5% lower (p < 0.0001) than new calibrations. Each new calibration equation adequately predicted soil moisture from the output for each instrument regardless of location or soil type. Prediction intervals varied, with errors of 4.5%, 3.5%, and 7.1% for the ECH2O, CT, and WCR, respectively. Only the ECH2O system was significantly influenced by temperature for the range sampled: as temperature increased by 1 °C, the soil moisture estimate decreased by 0.1%. Overall, the ECH2O performed nearly as well as the CT, and thanks to its lower cost, small differences in performance might be offset by deployment of a greater number of probes in field sampling. Despite its higher cost, the WCR did not perform as well as the other two systems.

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