Stream Simulation Design Methodology: A design methodology for adapting road crossing infrastructure (bridges and culverts) to climate change
Wednesday, September 9, 2020
2:00 pm Eastern Time
Robert Gubernick, R.G.
Watershed Restoration Geologist
USDA Forest Service
National Stream and Aquatic Ecology Center
In North America, Climate change has caused increases in frequency and intensity of large storm events which strain our existing transportation infrastructure which are typically undersized due to historical requirements from the hydraulic design method and to changes in hydrology. The research shows 25mm to 75mm storms have increased by 45 to 50% in the Eastern half of the United States. The US Forest Service manages ~612,000 kilometers of road across an extremely diversified landscape. Just in the last 8 years, the northeast region (13 national Forests) of the US Forest Service sustained over $52 million of damages from these large storms. Climate change adaptation of our infrastructure is imperative as we replace our road stream crossings and attempt to make society’s transportation system more flood resilient. The US Forest Service Stream Simulation Design methodology originally developed for Aquatic Organism Passage (AOP) has been shown to survive extremely large flood events (>>Q100 to Q500+ ) without structure loss or AOP passability with only minor if any repairs necessary. Stream simulation is a geomorphic design methodology that creates a stream channel within the road crossing structure in sync with the natural stream channel. This methodology is flexible as opposed to rigid, allowing the structure to adjust to aggradation and degradation, essentially making a structure invisible to the stream and enables the structure to survive floods larger than the design flood (Q100).