Approach
Shifts in landscape-level hydrology associated with climate change may pose risks to some facilities and infrastructure. Infrastructure and facilities are designed using historic hydrologic datasets to determine sizing and placement of units that meet access and safety criteria over a designed life-span (e.g. 25-100 years). However, current infrastructure will be subjected to conditions expected to exceed historical norms, placing some facilities and structures at risk. Considering potential changes to hydrology due to climate change may help inform structural reinforcements and safety enhancements that reduce risks. Current aged, undersized, and poorly maintained structures are likely to require additional effort to cope with the challenges of extreme heat on surfaces, heavy storm events, high water levels, increased winter soil moisture and extreme events. Planning and design that reduces risk of infrastructure failure may also benefit biologic integrity and other water quality and aquatic habitat goals.
Tactics
- Replace undersized culvert with bottomless culvert using the stream simulation design to allow for sediment and debris to safely pass during higher flow events.
- On low-volume roads or trails convert culvert to a low-water crossing structure (ford or low-water bridge) designed to be overtopped.
- Use full span structures without mid-span piers in areas with high likelihood of debris flows that may block smaller structures.
- Where lower levels of precipitation and drying conditions are expected,resurface roads to reduce dust with well graded materials that remain compact, and prepare to implement an enhanced dust abatement program.
- Re-engineer infrastructure drainages to reduce erosion potential on slopes by stabilizing existing rills, gullies and headcuts, and establishing diverse vegetation ground cover that increases surface roughness to adequately disperse and slow runoff.
- Reseal roadways more frequently to avoid rutting from precipitation or freeze-thaw cycles.
Strategy
Strategy Text
This strategy addresses actions for adapting infrastructure in forested watersheds, such as roads, skid trails, recreation trails, road-stream crossings, bridges, culverts, dams and other facilities associated with development. Infrastructure and transportation systems designs to avoid structural losses and damages by taking into account storm events and return periods documented in regional historical records. A changing climate may necessitate critical evaluation of past design concepts and criteria to minimize risks and safety concerns over the designed lifespan of the unit. Roads, skid trails, road-stream crossings, recreation trails, facilities, and other infrastructure are known to affect local landforms and hydrology, particularly where impervious surfaces concentrate water into flow pathways, generating high-velocity runoff and erosion. Added considerations in design may be necessary to accommodate altered hydrology and reduce risks of damage, failure or total loss. These considerations may be especially important near high-risk areas and where the consequences of lost infrastructure are unacceptable.
Shannon, P.D.; Swanston, C.W.; Janowiak, M.K.; Handler, S.D.; Schmitt, K.M.; Brandt, L.A.; Butler-Leopold, P.R.; Ontl, T.A. (in review). Adaptation Strategies and Approaches for Forested Watersheds. Ecological Applications.