Update: Finding drainage pipe with drones

Authors: Allred, Barry; ROUSE, GREG - Ross County Soil & Water Conservation District

Submitted to: Ohio Country Journal
Publication Type: Trade Journal
Publication Acceptance Date: 1/30/2020
Publication Date: 2/15/2020
Citation: Allred, B.J., Rouse, G. 2020. Update: Finding drainage pipe with drones. Ohio Country Journal. 28(10):14-15.

Interpretive Summary:

Technical Abstract: There are both economic and environmental reasons to map subsurface drainage systems in farm fields. Traditional drainage pipe location methods, such as tile probes and trenching equipment, are tedious, time consuming, and often cause pipe damage. Consequently, there is a critical need for effective, efficient, and non-destructive methods to map agricultural subsurface drainage systems, and aerial imagery obtained with drones can potentially provide a solution. Scientists from the USDA – Agricultural Research Service and the Ross County (Ohio) Soil and Water Conservation District continue working together to evaluate the capability of using aerial imagery from drones to map farm field drainage systems. Testing was done with a fixed-wing drone onto which one of three different cameras were mounted. Of the cameras utilized, one was a visible camera (image as would be seem with the human eye), one a multispectral camera (separate green, red, red edge, and near infrared images), and one a thermal infrared camera (image showing surface temperature variations). This drone technology was tested at over 30 locations in Indiana, Iowa, Michigan, and Ohio (with many of the Ohio sites located in Ross County). Drone aerial imagery was successful mapping drainage pipes (20% to 100% of drain lines detected) at well over 50% of the sites visited. Given any particular location, sometimes the visible camera worked best, oftentimes the multispectral camera proved to be the better choice, and for many farm fields, the thermal infrared camera proved to be most capable. While most of the drone surveys were conducted outside the growing season, there were some drone surveys conducted during the growing season in which drainage pipes were effectively mapped. At some field sites, drainage pipes were detected under very dry soil conditions, while at other locations, obtaining drone aerial imagery hours or a few days after a large rainfall seems to have an important impact improving drainage mapping. The time of day was found to significantly impact drainage pipe detection with thermal infrared imagery (late morning through late afternoon is best). A major issue confronting the use of drone aerial imagery for drainage mapping is distinguishing linear features due to drain lines from linear features resulting from farm field operations (tillage, planting, harvest, etc.). To address this issue, a set to criteria has been developed to differentiate drainage pipe linear features from farm field operation linear features. Overall, the application of drone aerial imagery for drainage mapping continues to exhibit substantial promise.