Integrated agrogeophysical approach for investigating soil pipes in agricultural fields

Authors: SAMAD, MUMAD - University Of Mississippi; WODAJO, LETI - University Of Mississippi; BAKHTIARI, RAD - University Of Mississippi; MAMUD, MD LAL - University Of Mississippi; HICKEY, CRAIG - University Of Mississippi

Submitted to: Journal of Environmental & Engineering Geophysics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2022
Publication Date: 12/1/2022
Citation: Samad, M.A., Wodajo, L., Bakhtiari, R.P., Mamud, M., Hickey, C. 2022. Integrated agrogeophysical approach for investigating soil pipes in agricultural fields. Journal of Environmental & Engineering Geophysics. 27(4):207-217.

Interpretive Summary: Soil erosion is the greatest challenge for soil management and agri-food production and is considered a severe threat to human habitat and livelihood. Although soil erosion due to surficial processes has been well studied, the role of the subsurface process, such as internal soil pipes, has often been overlooked. In this study the applicability of three agrogeophysical methods, i.e., seismic refraction tomography (SRT), electrical resistivity tomography (ERT), and ground-penetrating radar (GPR) for the detection of internal soil pipes is presented. The results of this study show that these agrogeophysical methods showed great potential for locating soil pipes. Implementing multiple techniques as described in this study will increase the certainty of soil pipe detection and help address the soil erosion problem. Further research is recommended to quantify the dimensions and amount of soil loss due to internal soil pipes. The results of this study reveal valuable tools for stakeholders interested in controlling soil loss from agricultural fields to secure food demand for the growing population. The results also improve the ability to detect soil pipes and other faults in aging earthen dams, which can allow them to be repaired and avoid catastrophic dam failure scenarios.

Technical Abstract: Locating, measuring, and mapping internal soil pipes and their networks are vital to assess the total soil loss in agricultural fields. Internal soil pipes are not commonly visible at the surface, and their subsurface networks rarely follow the surface topography. The hidden and uncorrelated nature of occurrences narrows down the applicability of manual and remote sensing-based techniques. Noninvasive agrogeophysical methods can overcome these limitations by providing detailed subsurface pictures with high spatial resolution. In this study, the applicability of three agrogeophysical methods, i.e., seismic refraction tomography (SRT), electrical resistivity tomography (ERT), and ground-penetrating radar (GPR), for the detection of internal soil pipes is presented. The measurements are taken at Goodwin Creek, an experimental field site with established internal soil pipes. Agrogeophysical signatures of soil pipes are verified using a cone penetrologger (CPL) method. The verified agrogeophysical signatures are presented in cross-sections providing insights into the spatial position and distribution of internal soil pipes over the study area. The study showed that soil pipe affected zones are indicated with low P and S wave velocity anomalies. ERT results indicated the location of soil pipes with high resistivity anomalies. However, both SRT and ERT lack the resolution to identify individual soil pipes. GPR diffraction hyperbolas and their apexes effectively indicated soil pipes' lateral location and depth.