RIVER RESTORATION DESIGN CONSIDERATIONS FOR LARGE WOODY DEBRIS WITH RESPECT TO BOATER SAFETY

Greater awareness of geomorphic and aquatic habitat values of instream woody debris over the last two decades has led to its increasing usage in river restoration actions. Recreational river traffic has boomed over the last 50 years during a period of historic low levels of instream woody debris abundance. Safety concerns regarding instream wood placement have come to the forefront of planning and designing river restoration projects.

Wood composes only a small portion of the river hazard domain, but one that occupies a high profile. Safety concerns are now used to justify maintaining low levels of wood, despite known ecological benefits from increasing wood volumes. A myriad of environmental and victim-specific conditions factor into any safety incident. However, recent regulations and guidelines adopted under the auspices of improving boater safety assume a one-way deterministic relationship between project actions and user safety. Further, designers are often expected to assume a higher level of liability for wood treatments in natural systems than traditional civil projects in built environments.

The presentation will put wood risk to boaters into context, and discuss simple, effective mitigation options. Content draws on the collective experience of the authors, who have floated over 3,500 miles as recreational boaters and placed over 4,000 pieces of large woody debris as stream restoration practitioners.