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Production of sediment from the running surface of unpaved legacy roads in southeast Ohio, USA

Silliman, Benjamin A., Toman, Elizabeth Myers
International journal of forest engineering 2019 v.30 no.2 pp. 99-108
anthropogenic activities, aquatic habitat, best management practices, drinking water, roads, runoff, sediment yield, sediments, storms, stream channels, summer, tires, traffic, water quality, watersheds, Ohio
Unpaved, or unbound aggregate, roads are thought to be one of the largest anthropogenic sources of fine sediments in the stream channels of small watersheds. Sedimentation can reduce water quality in streams negatively impacting aquatic habitat as well as being a detriment to municipal drinking water sources. Even during periods of low-volume use roads can be a chronic source of fine sediment. Legacy roads may degrade stream water quality more than newly built roads as they were constructed before modern best management practices. This study measured the production of sediment from the road surface of a legacy road system within a small watershed using controlled precipitation experiments to determine the mass of sediment that roads could produce during one storm event. Sediment production was not related to road slope or strength as measured by Clegg hammer. The production of sediment from the road surface increased 95% on average with wet traffic use. Using an estimated road and stream connectivity of 50%, surface runoff from the roads in Middle Creek watershed could account for 16% of the total sediment yield from the watershed during a small summer storm event. Compacted tire tracks were utilized as flow paths during runoff experiments, emphasizing the importance of continual maintenance and best management practices. This study highlights the need to disconnect unbound aggregate roads from stream channels in order to prevent negative water quality impacts associated with sedimentation.