Abstract

BURROUGHS, KAITLIN. The Effectiveness of Trail Drainage Features: A Field Assessment Tool and an Examination of Influential Factors. (Under the direction of Dr. YuFai Leung). Park and protected area managers combat trail degradation by constructing and maintaining trail drainage features (TDFs), and trail sustainability depends on the effectiveness of these features in diverting surface runoff from the trail tread. While trail construction guidelines and handbooks are common, little empirical research has been devoted to examining the factors that influence the effectiveness of TDFs, nor are field tools to assess their conditions. This study aims to better understand TDF effectiveness with two objectives: 1) developing and testing a field TDF assessment method, and 2) examining key factors that influence the effectiveness of TDFs. This study took place on the Appalachian National Scenic Trail (AT) in the summer of 2015. Twenty-one 5-km segments were chosen along the northern one-third portion of the AT from Connecticut to Maine using a generalized random tessellation stratified (GRTS) sample design. In each segment, every fifth TDF was assessed, resulting in a sample size of 117 TDFs. The field assessment tool consists of 27 measurements in four categories, including TDF characteristics, sediment characteristics, trail characteristics, and maintenance along with an effectiveness rating adopted from a previous study. The assessment tool was presented and inter-rater reliability reported in the first paper. Results showed a moderate agreement for measurements trench depth, trail grade, and canopy cover and high agreement on measurements material type, structural stability, and trench extension. The factors influencing the effectiveness of TDFs were examined using logistical regression and contingency. TDF height, trench depth, erosion presence downhill, and the overall effectiveness rating were selected as effectiveness indicators (dependent variables). Analysis results indicated TDF thickness, TDF length, trail slope alignment (TSA) angle, and material type were four key factors influencing TDF effectiveness. A wood material type, larger thickness, and higher TSA angles (closer to 90 degrees) correlated with positive (deeper) trench depth levels, while TDFs with longer lengths correlated with undesirable TDF height levels. The study concludes with a developed field assessment tool that land and trail managers can use to better understand the effectiveness of existing TDFs within their jurisdiction. Additionally, recommendations are given for the best scenario in which to build and maintain TDFs, such as contoured trails (trails with TSA angles closer to 90 degrees) with a maximum tread width of 2m using wooden materials that are a minimum of 12cm thick. Additional research is needed on larger-scale drainage features such as grade reversals and trail side sloping, as well as comparative studies of how these systems work in relation to TDFs. © Copyright 2016 Kaitlin Burroughs All Rights Reserved The Effectiveness of Trail Drainage Features: A Field Assessment Tool and an Examination of Influential Factors by Kaitlin Burroughs A thesis submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the degree of Master of Science