Chapter 3: Monitoring Treatments to Reduce Sediment and Hydrologic Effects from Roads
Timothy J. Beechie, Curt N. Veldhuisen, Eric M. Beamer, Dave E. Schuett-Hames, Robert H. Conrad, and Paul DeVries
Roads alter hydrologic regimes (Harr et al. 1975; King and Tennyson 1984; LaMarche and Lettenmaier 2001) and sediment supply to streams (e.g., Sidle et al. 1985), which influence channel and habitat characteristics (e.g., Cederholm et al. 1982; Tripp and Poulin 1986a, 1986b; Hicks et al. 1991) and ultimately impact aquatic biota (Waters 1995). Road drainage connections to stream channels (e.g., ditches draining to streams) can alter the amount and the timing of water delivery to streams, as well as the delivery of sediment eroded from hillslopes or road surfaces (Croke and Mockler 2001; Madej 2001). Roads also alter sediment supply through increased frequency of landsliding (Dyrness 1967; Megahan and Kidd 1972; O’Loughlin 1974; Sidle et al. 1985) and increased surface erosion (Packer 1967; Reid and Dunne 1984; Bilby et al. 1989). Actions to reduce sediment delivery from roads can address any of these processes, with the intent of reducing sediment supply to streams and quantities of sediment in channels or in the water column (e.g., Kochenderfer and Helvey 1987; Furniss et al. 1991; Madej 2001). Those actions, however, will require vigorous monitoring to determine their effectiveness.