Application of GPR ground wave for mapping of spatiotemporal variations in the surface moisture content at a natural field site

摘要

In the present study GPR ground wave (GW) was used to monitor the spatial distribution of surface moisture content at a natural Kanto loam site. To map the soil moisture variations, measurements were conducted on a regular interval of 2-3 days per week. Results revealed that ground wave data were sensitive to the upper surface soil conditions as well as seasonal variations. Significant increase in the moisture content values were observed a day after a precipitation event. However, moisture content increase was non-uniform over the entire area; the probable cause of the variations might be associated with soil hydraulic properties (e.g. hydraulic conductivity, water retention characteristics), and/or topography of the site. The GW sampling depth obtained by taking one quarter of wavelength (Pallavi, 2009) was found more reliable with the reference measurements. The GW sampling depth was found to be between 0.06 - 0.07 m at this site. The study shows that the GPR GW can be used as a principal tool for large scale spatiotemporal monitoring in non-invasive and rapid mode with high resolution and provides quality data with known sampling volume at a field scale.