Correlation between near-surface electromagnetic soil parameters and early-time GPR signals: An experimental study

Abstract

We explore a new approach to evaluate the effect of soil electromagnetic parameters on early-time ground-penetrating radar (GPR) signals. The analysis is performed in a time interval which contains the direct airwaves and ground waves, propagating between transmitting and receiving antennas. To perform the measurements we have selected a natural test site characterized by very strong lateral gradient of the soil electrical properties. To evaluate the effect of the subsoil permittivity and conductivity on the radar response we compare the envelope amplitude of the GPR signals received in the first [Formula: see text] within [Formula: see text]-wide windows, with the electrical properties ([Formula: see text] and [Formula: see text]) determined using time-domain reflectometry (TDR). The results show that the constitutive soil parameters strongly influence early-time signals, suggesting a novel approach for estimating the spatial variability of water content with GPR.

Water content evaluation in unsaturated soil using GPR signal analysis in the frequency domain

“…It is the obvious consequence of the increasing of the dielectric permittivity of soil when the moisture content increases. Some authors showed that the amplitude of the reflected GPR signal decreases as the soil humidity increases (Pettinelli et al, 2007).…”

“…The algorithm estimates the shallow soil properties using the early-time arrivals, i.e. the arrivals recorded before subsurface reflections arrive (Pettinelli et al, 2007). The amplitude and shape of the early-time arrivals change with soil permittivity, conductivity, and antenna standoff.…”

In situ measurements of soil colour, mineral composition and clay content by vis–NIR spectroscopy

“…For example, the use of electromagnetic induction (EMI) and electrical resistivity for measurements of soil electrical conductivity (Sudduth et al, 2001), magnetic susceptibility for measuring soil contamination by heavy metals (Jordanovaa et al, 2008), ground penetrating radar (GPR) for measurements of soil water content (Pettinelli et al, 2007), proximal passive γ-ray spectrometry for measuring K, U, Th, sand, clay and iron contents , cameras to measure soil colour and estimate soil organic carbon and iron contents (Sudduth and Hummel, 1988;Viscarra Rossel et al, 2008), diffuse reflectance spectroscopy using visible-near infrared (vis-NIR) and mid infrared (mid-IR) energies to estimate soil organic carbon (OC), clay content, mineral composition and other soil properties (e.g. BenDor and Banin, 1995;Stenberg et al, 1995;Reeves and McCarty, 2001;Shepherd and Walsh, 2002;Demattê et al, 2004;Brown et al, 2006;Viscarra Rossel et al, 2006a), ion-sensitive field effect transistors (ISFET) and ion-selective electrodes to measure soil pH, lime requirement and soil nutrients (Adamchuk et al, 1999;Viscarra Rossel and Walter, 2004;Adamchuk et al, 2005;Viscarra Rossel et al, 2005;Sethuramasamyraja et al, 2008), and mechanical draft systems for measuring soil strength (Hemmat and Adamchuk, 2008).…”

Uso do atributo amplitude instantânea do dado gpr na avaliação do teor de umidade de solos e sedimentos

“…Alterações nas propriedades petrofísicas do meio relacionadasàs variações dos teores de umidade nos poros se traduzem em diferenças nas propriedades elétricas do meio (permissividade dielétrica e condutividade elétrica), e consequentemente em mudanças nos atributos da onda no seu percurso. Pettinelli et al (2007), restringindo a análise do atributo amplitudè a janela temporal que contém apenas o registro da onda direta, sugeriram seu emprego para a estimativa da variação espacial do teor de umidade da subsuperfície rasa.…”