Locating Drainage Tiles at a Wetland Restoration Site within the Oak Openings Region of Ohio, United States Using UAV and Land Based Geophysical Techniques

Richard H Becker,Kennedy O Doro,Anna M Becker

doi:10.1007/s13157-021-01495-6

Abstract

Drainage tiles were used to drain wetlands in the midwestern United States to convert them into farmlands. With decades of farm operations, utility maps showing tiles’ locations are now mostly inaccurate or simply do not exist. However, knowledge of the location of tile networks is needed to effectively restore these farmlands to their original wetlands’ conditions. With many fields spanning several hectares, efficiently locating drainage tiles at large farm fields can be problematic. Drainage tiles create variations in soil physical properties including moisture content, surface temperature and dielectric permittivity within and around the pipes which can be sensed by geophysical methods. Our study assesses the application of electromagnetic radiation via visible and thermal infrared imaging using an unmanned aerial vehicle and ground penetrating radar (GPR) to locate drainage tiles at large farm field scale. The study was conducted at the Sandhill Crane wetland, a 1.1 km2 old agricultural field located in Swanton, Ohio. A UAV equipped with visible and thermal infrared cameras acquired imagery on a regular grid and about 100 GPR lines were measured using a 250 MHz radar system. Both visible and thermal infrared images identified the drainage tiles and their orientations. GPR profiles reveal the drainage tiles mostly in a parallel East-West direction. By using a UTV to pull the GPR system, we efficiently collected data along profiles covering the entire site. The delineated tile network will improve management of the anthropogenically altered hydrology at the site as it is being restored into its original wetland conditions.

Highlights

Drainage tiles have been extensively used in what was historically known as the Great Black Swamp in the Midwestern region of the United States since the late 1800s to drain excess water and lower the water table for settlement and related activities including farming (Andreas and Knoop, 1992; Kaatz, 1955)
Our study assesses the application of electromagnetic radiation via visible and thermal infrared imaging using an unmanned aerial vehicle and ground penetrating radar (GPR) to locate drainage tiles at large farmfield scale
This study further evaluates the use of both unmanned aerial vehicle (UAV)-based visible and thermal infrared imaging and land-based ground penetrating radar for locating drainage tiles and mapping their network at a large field scale within the Oak Openings Region of Northwestern Ohio

Summary

Introduction

Drainage tiles have been extensively used in what was historically known as the Great Black Swamp in the Midwestern region of the United States since the late 1800s to drain excess water and lower the water table for settlement and related activities including farming (Andreas and Knoop, 1992; Kaatz, 1955). Northwestern Ohio and part of Michigan and Indiana constituted a vast wetland refered to as the “Black Swamp” with its low lying lands partially or entirely covered with water in the winter and spring (Kaatz, 1955). This once vast wetland area has been largely drained to accommodate human settlements and farmlands leaving behind less than 5 % of the earlier wetland area (Lenhart and Lenhart, 2014). The narrow region west of Toledo, Ohio which extends to the west of Michigan named the Oak

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