Mapping subsurface drainage in agricultural areas using unmanned aerial vehicle imagery and ground penetrating radar

Authors: KOGANTI, TRIVEN - Aarhus University; GHANE, EHSAN - Michigan State University; Martinez, Luis; IVERSEN, BO - Aarhus University; Allred, Barry

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 10/15/2019
Publication Date: 11/15/2019
Citation: Koganti, T., Ghane, E., Martinez, L.R., Iversen, B.V., Allred, B.J. 2019. Mapping subsurface drainage in agricultural areas using unmanned aerial vehicle imagery and ground penetrating radar. Proceedings of the 1st Indian Near Surface Geophysics Conference & Exhibition. 76-80.

Interpretive Summary:

Technical Abstract: Subsurface drainage systems are commonly installed in agricultural areas to remove the excess soil water. Knowledge of the position of the existing drainage network is often lacking. This complicates 1) the understanding of increased leaching and offsite release of nutrients and in turn the development of eutrophication mitigation strategies and 2) retrofitting the new drain lines within the existing drainage system to increase drainage efficiency. The conventional methods of drainage mapping include the use of tile probe and trenching equipment, which are invasive, laborious and often inefficient to apply at large spatial scales. Recent technological developments in non-destructive techniques (NDT) provide a potential alternative solution. In this study, we explore the suitability of unmanned aerial vehicle (UAV) imagery collected using three different cameras (visible-color, multispectral and thermal infrared) and a ground penetrating radar (GPR) for subsurface drainage mapping. Both these techniques are complementary in terms of their usage, applicability and the properties they measure. While UAV imagery is useful in measuring surface soil and plant properties and the flights can cover large areas in limited time, the GPR works the best to understand subsurface variation in soil electrical properties and is comparatively hard to employ across large areas. Both these techniques were applied at three different sites near Mount Gilead, OH; Clayton, MI, and Palmyra, MI in the Midwest U.S. At the Mount Gilead site, it was possible to delineate the location of drainage pipes using both the UAV imagery and GPR, hence, providing a suitable validation technique and depth information. At the Clayton site, while UAV imagery was successful on the western part of the field, GPR proved to be useful in the eastern part where the UAV imagery failed to capture the drainage pipe locations. At the Palmyra site, less to no success was observed in finding the drain lines using UAV imagery, while good success was achieved using the GPR. Although UAV imagery seems to be an attractive solution for mapping subsurface drainage systems as it is cost effective and can cover large field areas, the results suggest the usefulness of GPR to complement the UAV imagery as both a mapping and validation technique. Future research focuses on understanding the dependence of the UAV imagery and GPR on the soil type, crop residue, tillage practice, ground wetness level and rainfall event prior to the surveys with the aim of developing guidelines in relation to the choice of sensor for subsurface drainage mapping.