Approach
Roads and trails are experiencing an increased incidence of flood damage as a result of increased rates of heavy rain events. This impact is most pronounced in the Northeast and Midwest, though it is occurring with increasing frequency and intensity throughout the United States. Inadequate drainage systems on roads and trails can produce both high-velocity overland flows and increased soil saturation that creates boggy areas. Both of these conditions, which stand to increase with climate change, have the likelihood of damaging adjacent natural resources and impacting ecosystem functions. The continued maintenance of roads and trails is expected to increase in frequency and cost, especially in heavily used areas, as high winter streamflows and high magnitude floods become more common. Upgrades, repairs, and improvements are tactics that can address inadequate drainage. Yet, in a changing climate, addressing inadequate infrastructure may also include altering or decommissioning routes to reduce recreational access where it is no longer sustainable.
Tactics
- Incorporate reverse grade dips, open drainages/dips, oversized culverts, angle design/outsloping, water bars, and ditches onto trails and access routes in order to disperse surface water and reduce hydrologic connectivity to stream systems.
- Reduce allowable weight on vulnerable roads that consistently require maintenance or repair.
- Harden road and trail surfacing with gravel or rockwork, especially at approaches to water crossings or in areas that are prone to hold or channel water.
- Construct boardwalks to elevate and lessen impacts of trails that are located near wetlands or consistently saturated soils.
- Install drain tile or French drains below trails and roads, concurrently elevating the surface of the trail or road.
- Convert roads to trails where older roads are under-utilized and unsustainable.
- Decommission roads and remove culverts from areas vulnerable to flooding or landslide that present the risk of consistently delivering sediment to natural waterways.
Strategy
Strategy Text
Projected changes in precipitation and temperature are expected to alter hydrologic regimes through changes in streamflow, snowpack, evapotranspiration, soil moisture, surface runoff, infiltration, flooding, and drought. Many of the roads, trails, campgrounds, and other infrastructures that support recreational activities were constructed in a manner that restricted stream-channel flow and reduced floodplain connectivity, among other hydrologic alterations, which today has produced an inability to adequately accommodate higher peak flows and flooding, especially during extreme precipitation events. Damage to roads, trails, campgrounds, and other infrastructure brings with it the potential of damage to natural resources, especially where impervious or below-grade surfaces concentrate water into flow pathways, generating high-velocity runoff and erosion of soils. This strategy describes options to prepare for uncharacteristic hydrologic events in order to reduce the extent or severity of damage to both recreational infrastructure and adjacent natural resources. It is important to keep in mind that modifications to maintain hydrology at one site may have negative impacts on hydrology at another site.
O’Toole, D.; Brandt, L.A.; Janowiak, M.K.; Schmitt, K.M.; Shannon, P.D.; Leopold, P.R.; Handler, S.D.; Ontl, T.A.; Swanston, C.W. Climate Change Adaptation Strategies and Approaches for Outdoor Recreation. Sustainability 2019, 11, 7030.