Date of Completion

2020

Document Type

Honors College Thesis

Department

Geography

Thesis Type

Honors College

First Advisor

Beverley C. Wemple

Keywords

Erosion, Phosphorus, Transportation, Lake Champlain, Roads

Abstract

Water is a precious resource for human life and environmental health, however, human activity contributes a wide variety of contaminants to freshwater systems. Soil erosion adds nutrients, sediment, and pollutants to the water, and contributes to declining water quality downstream. Road networks are particularly important in this context, because roads interrupt the flow of water, often increasing the erosive power of adjacent materials, causing serious local erosion. Despite the importance of roads in the process of water quality impairment, little is known about the severity of this issue or the factors that drive it. This project investigates the magnitude of gully erosion as an issue on Vermont's roads. High-resolution three-dimensional scans of selected gullies are compared with municipal and state gully inventories to determine the general distribution and severity of these erosive features. Five towns were selected for a focused geospatial analysis of existing Road Erosion Inventory data to survey the magnitude of gully erosion on the local level. Contributing factors were statistically compared to determine what land features have the greatest effect on the probability of extreme erosion from concentrated outfalls. Soil tests were conducted to estimate the total mass of mobilized sediment-bound phosphorus associated with this form of erosion. The study's findings show that gully erosion from roads has the potential to mobilize up to hundreds of kilograms of sediment-bound phosphorus over the course of a single gully's development. Rough calculations using the results of this experiment indicate that gully erosion at concentrated outfalls could be producing nearly 11% of Lake Champlain's yearly phosphorus input. The study illuminates Vermont's need for more comprehensive surveys of existing road drainage features. The methods and findings of this research will inform further investigation of the phosphorus runoff reduction potential of repairs made to gullies at concentrated outfalls on Vermont's roads.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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