Project Timeline:
July 1, 2013 - March 31, 2029
CMER Scientist:
Jenelle Black
Principal Investigator:
Charlie Luce
Project Manager:
Alexander Prescott
Rule Group:
Roads
SAG:
N/A, overseen directly by CMER
Roads are persistent sources of fine sediment to forest streams, which otherwise have characteristically clear water except during significant storm events. Substantial improvements in water quality have been secured in recent decades through diligent application of mitigation measures (usually called best management practices or “BMP”) for sediment from forest roads. However, there are still some locations where noticeable loading occurs related to forest roads. Recent work has demonstrated that sediment delivery from forest roads is focused in a small fraction of the road network. A Washington study found that only 10-11% of the forested road length is delivering sediment to the channel network. Work in Oregon and Idaho shows that 90% of the delivered sediment comes from less than 9.2% of the drainage points. That fraction is primarily comprised of larger, more heavily travelled roads in proximity to streams. A survey of over 5,000 drainage points in Western Montana and subsequent sediment modeling found that 76% of road sediment delivery occurred within 10 meters of the stream. Mitigation for these locations has proven more challenging than in other places, and better information is needed to hone our capacity to efficiently handle sediment from these high-traffic, near-stream (HTNS) road segments.
Thus, a central question is what combinations of surfacing, ditch line management, traffic control, and drainage management will most efficiently and effectively mitigate sediment yields and hydraulic effects from HTNS roads? The question pivots on combinations because significant information on what individual treatments such as rocking or traffic changes can do to mitigate sedimentation already exist. Such information has been formulated into simple empirical approaches that estimate sediment yield from a road surface based on several empirically-derived multipliers similar to the Universal Soil Loss Equation (USLE). Importantly, these efforts depend on two pivotal assumptions: 1) That implementation of multiple BMP has the expected positive benefits; and 2) That those positive benefits are additive, multiplicative or synergistic. BMP treatments are rarely used in isolation and it is the combination of multiple BMP that has been inadequately studied. Under selected circumstances, one BMP may even reduce another’s effectiveness. These key issues of most previous research and the simple, multiplicative nature of existing models fundamentally drive the sample design of this project.
Project Manger
CMER Scientist
Principal Investigator, United States Forest Service (USFS)
Project Team Member, United States Forest Service (USFS)
Project Team Member, Rayonier Inc.
Project Team Member, University of Washinton
Project Team Member, University of Washinton
No documents associated with this phase.