A method to estimate soil water content based on multi-offset ground-penetrating radar (GPR) data
Abstract
For the last five years, South Korea has experienced about 4,000 subsidence events, and the frequency of occurrence drastically increases every year. In particular, subsidence in urban areas causes increasing damage to both humans and property. Urban subsidence can be investigated by various methods like resistivity survey, GPR exploration, and boring test. The GPR exploration is most widely adopted, since it is a nondestructive method that can investigate a wide area in a relatively short time. The conventional GPR measurement applied the common-offset approach, which fixes the space between transmitter and receiver; data processing is minimally needed to create underground structure images. However, such common-offset measurement is limited in collecting necessary information for preventing and managing ground subsidence. To overcome the above limit, this study proposes a multi-offset GPR approach. Since the multi-offset measurement utilizes one transmitting antenna and multiple receiving antennas, a radar wave can penetrate the substrate through multiple paths. Multi-offset GPR data, thus, can create underground structure images with a better signal-to-noise ratio, as compared to the common-offset measurements, but needs a more data processing technique. However, the common-reflection-surface (CRS) stack calculates wave characteristics from data to identify common reflection surface without being affected by a velocity model for underground media. Consequently, this method does not need such complex processing of the multi-offset measurement and wave characteristics can be used to calculate the interval velocity of a radar wave. This study utilizes multi-offset GPR data with the CRS method to estimate volumetric water contents. We collected a multi-offset data with 200 MHz antenna and found the CRS-based radargrams exhibit an improved signal-to-noise ratio compared the common-offset data. RMS velocity was calculated from the attribute values obtained by the CRS stack process and thus the velocity variation of the pipeline buried in the infill sediment layer could be identified. Here we present a case study applying the CRS method to process the multi-offset GPR data in order to identify the variation of volumetric water content in soil layers beneath pavement.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMNS31C0771C
- Keywords:
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- 0933 Remote sensing;
- EXPLORATION GEOPHYSICSDE: 1829 Groundwater hydrology;
- HYDROLOGYDE: 1835 Hydrogeophysics;
- HYDROLOGYDE: 1880 Water management;
- HYDROLOGY