Quantifying Gully Erosion and Potential for Sediment and Phosphorus Pollution Reductions Achieved by Erosion Remediation Projects on Vermont’s Roads
-
2021-07-16
Details:
-
Creators:
-
Corporate Creators:
-
Corporate Contributors:
-
Subject/TRT Terms:
-
Publication/ Report Number:
-
Resource Type:
-
Geographical Coverage:
-
Edition:Final Report 2019-2021
-
Corporate Publisher:
-
Abstract:Erosion at road drainage outfalls and culvert outlets contributes to water quality impairment by discharging stormwater, sediment, sediment-bound nutrients, and other water quality contaminants to receiving waters. In Vermont, past work has quantified the importance of road surface and roadside (i.e. ditch) erosion to water quality impairment and provided insights into the effectiveness of best management practices in addressing this impact. This study documented rates of gully erosion at road drainage outfalls and culvert outlets in northern Vermont, quantified phosphorus content of eroded soils, assessed efficacy of erosion mitigation practices, and provided a first-order estimate of the magnitude of gully erosion relative to base loads for phosphorus contributions to receiving waters. The authors used terrestrial LiDAR scanning to conduct ground surveys at 13 intensively monitored sites and multi-date airborne LiDAR data to conduct GIS-based assessments at culverts in 35 northern Vermont towns. Soil sampling at the 13 intensively monitored sites was used to quantify soil bulk density and phosphorus concentration. The efficacy of erosion mitigation projects was assessed through the installation and monitoring of experimental “treatments” at a set of the intensively monitored sites and through the retrospective assessment of a larger set of sites where erosion mitigation projects had been installed in the past. The authors found that the rate of gully erosion varies widely across sites studied and relates to both site conditions and weather variability (as measured by precipitation magnitude). Erosion mitigation practices were highly effective in reducing gully erosion at the experimentally installed sites and appear to remain largely intact, functioning to provide water quality benefits at the retrospectively assessed sites. A first order “upscaling” of the study observations suggests that gully erosion is a modest contributor to loads of phosphorus in receiving waters of the Lake Champlain basin. Where the incidence of gullies is high and rates of gully erosion large, erosion mitigation can provide valuable water quality benefits and contribute to the resilience of valuable transportation infrastructure in the face of climate change. The authors lay out some recommendations for using research results for crediting erosion remediation under the Lake Champlain TMDL for phosphorus and comment on the broader implications of this research for other communities, workforce development, and research stakeholder partnerships
-
Content Notes:PDF contains final report and appendices.
-
Format:
-
Funding:
-
Collection(s):
-
Main Document Checksum:
-
File Type:
Supporting Files
-
No Additional Files
More +