Toward modeling traffic-induced forest road erosion: field investigations and process-based model conceptualization

Abstract

Though abundant anecdotal and empirical evidence of increased erosion on forest roads due to traffic exists, the literature lacks a holistic treatment of the ways in which traffic and other important contextual covariates influence runoff and erosion on forest roads. The main goal of my dissertation is to examine the relationship between forest road erosion, traffic, and potential erosion control treatments through literature synthesis, small-scale field experiments, and the conceptualization of a comprehensive process-based model. In Chapter 2, I discuss current hypotheses of how traffic affects forest road erosion, what data are required to validate those hypotheses, and present the motivation for developing a process-based model of forest road erosion. In Chapter 3, I evaluate the efficiency of multiple roadside ditch line erosion control treatments using ditch line roughness, discuss the theory behind using roughness as an efficiency metric, describe the methodology of the experiment, and present results from the experiment. In Chapter 4, I use unoccupied aerial vehicle (UAV) structure-from-motion (SfM) technology to examine how wheel ruts evolve on mainline logging forest roads following maintenance of the road surface. The implications of said rut formation on the road surface drainage system and erosion potential are discussed in detail. Finally, in Chapter 5, I lay the theoretical foundation for a process-based model that includes mathematical conceptualizations of traffic-induced local sediment production as well as road-segment-scale sediment transport.