Approach
Erosion is anticipated to increase as seasonal precipitation and storm intensities change, altering soil moisture regimes, and runoff. Sites already prone to erosion may have increased risks of sediment losses in a changing climate, particularly sites with sparse canopy, sparse litter cover, steep slopes, and impervious surfaces. Excessive sedimentation and deposition of fine materials can negatively influence watershed hydrology and flow pathways, water quality (e.g. clarity, chemical composition), and potential survival and regeneration of plants, aquatic and terrestrial wildlife. Best management practices to avoid soil losses can help prepare and protect sites from the added challenges associated with extreme events, increased frequency of rain events, seasonal variations in soil moisture and more frequent overland flows in all seasons.
Tactics
- Maintain vegetation, or revegetate shoreline banks to absorb and dissipate water velocity and energy.
- Slow road surface drainage and reduce sedimentation by directing water into forested or densely vegetated areas with lead off ditches, broad based dips, bioswales and water bars.
- Avoid road or skid trail construction adjacent to surface waters to minimize direct discharge to streams, evaluate area for potential sediment input and design stream-crossing to meet expected flow conditions.
- Use temporary ground covers to increase floatation of harvesting equipment, in order to reduce surface disturbances during forest management operations.
- Delay harvests following heavy rains and avoid timber harvesting activities prior to expected rain events.
- Use erosion resistant materials and slope stabilization methods around cross drain culverts to reduce risks of erosion after short duration, high intensity rainfall events.
Strategy
Strategy Text
This strategy addresses the additional efforts necessary to sustain clean water in a changing climate, with an emphasis on anticipating and preventing increased stresses before water quality impairment occurs. Forest managers may already implement actions that avoid degradation to water quality, but water quality is expected to change, possibly worsen in some areas due to changes in seasonal precipitation regimes and warming. As hydrology and ecosystems change reflecting a changing climate, these changes are likely to combine with existing land-use issues to further degrade or diminish water quality. These changes may result in altered water chemistry, increased mobilization of pollutants and sediments to surface waters, altered pollutant resident times, and increasing water temperatures.
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.