Graduation Date

Fall 2020

Document Type

Thesis

Program

Master of Science degree with a major in Natural Resources, option Forestry, Watershed, & Wildland Sciences

Committee Chair Name

Dr. Andrew Stubblefield

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Dr. Joe Wagenbrenner

Second Committee Member Affiliation

Community Member or Outside Professional

Third Committee Member Name

Dr. Lee MacDonald

Third Committee Member Affiliation

Community Member or Outside Professional

Fourth Committee Member Name

Dr. Kevin Boston

Fourth Committee Member Affiliation

Community Member or Outside Professional

Subject Categories

Forestry

Abstract

Sediment delivery from unpaved actively-used and relatively un-trafficked forest roads are one of the most common sources of impairment to aquatic ecosystems. Hence the objectives of this study were to: 1) compare the variability in erosion rates from actively used and relatively un-trafficked timber harvest roads across multiple water years in Railroad Gulch; 2) identify segment scale controls on road surface erosion and road-to-stream connectivity; 3) develop storm-based and annual segment scale models to predict road sediment production and compare the accuracy of these models to WEPP: Road; and 4) estimate road-related sediment loads to streams.

Between 2014 and 2019 mean plume lengths were four meters for active roads and two meters for inactive roads, whereas mean rill lengths were three meters on inactive roads and two meters on active roads. Only plume deposition proved significantly greater (α < 0.01) on active roads compared to inactive roads.

The annual-based multiple regression model over-predicted sediment production by 28 percent and the storm-based underpredicted by 37 percent. WEPP: Road underestimated annual sediment loads by 95 percent. Segment-scale sediment production is significantly correlated (α < 0.01) to the slope*area of a road segment, increased rill length (m), percent bare soil, and summed storm erosivity (MJ mm ha-1 h-1).

Sediment production rates for active and inactive roads in Railroad Gulch ranged from 0.0 kg m2 yr-1 to 4.8 kg m2 yr-1. Since between one and two percent of active road lengths and between four and nine percent of inactive road lengths were connected between WY 2017 and 2019, an estimated five Mg and nine Mg of sediment would have delivered to the East and West Branch Railroad Gulch, respectively.

Citation Style

Faubion, C.F., 2020. Sediment Production and Delivery from Timber Harvest Roads in Humboldt County, California. MSc thesis. Humboldt State University, Arcata, CA.

Share

Thesis/Project Location

 
COinS