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STREAMBANK EROSION CONTROL ALTERNATIVES Frank Reckendorf, PhD (Reckendorf and Associates Salem,OR [email protected]) (volunteering for SERNW) Barry Southerland, PhD (USDA, Natural Resources Conservation Service, West National Technical Support Center, Portland, OR [email protected]) for PNWSWS & SERNW, Vancouver, WA May 4, 2005 STREAMBANK EROSION CONTROL ALTERNATIVES Planning, Evaluation, and Design Overview Workshop – May 4th, 2006 NW Chapter Society of Ecological Restoration – Vancouver, WA Understanding Process Understanding the Resource Problem Understanding the reference and desired future condition Using system(s) (fluvial and watershed approaches) to solve streambank erosion problems Introduction Workshop Housekeeping Participant Introductions Binder, Design to Dirt CD, Soil Bioengineering, Hoag and Fripp, 2002 Design to Dirt Contents Review (see Binder) Minimum Time Spent in Workshop on Some Slides Because of Time Frame, but “All Slides” will be in the Follow-up CD What Is Streambank Erosion? Streambank erosion is that part of channel erosion in which material is eroded from the streambank and deposited at the base of the slope or in the channel. Streambank erosion is usually associated with erosion of the streambed. It occurs along perennial, intermittent, and ephemeral streams. Planning and Evaluation Any evaluation of streambank erosion should be done in a planning and evaluation context that is cyclic. In other words there is a cycle and feedback from objectives to resource evaluation to cause and effect to solutions to objectives. Planning Steps Determining Objectives Assessment Including Appropriate Environmental Assessment – Physical – Biological – Chemical – Archeological – Social Planning Cont. Interpreting, and Analyzing Developing Alternatives Documenting Decisions Establish Funding and Env. Clearance Implementation Monitoring Restoration Planning (see SER PRIMER sec. 3) A clear rational as to why restoration is needed A statement of the goals and objectives of the restoration project An ecological description of the site designated for restoration An ecological description of the reference (see page 8 of PRIMMER multiple sites) East Side Stream in Valley Type “V”, (Glacial-Fluv. Trough) Refer. Reach White River, WA East Slope Cascades Restoration Planning Cont. An explanation of how the proposed restoration will integrate with the landscape and flows of organisms and materials Restoration Planning. Cont. Explicit plans, schedules, and budgets for site preparation, installation and post installation activities, including a strategy for making prompt mid-course corrections. Well developed and explicitly stated performance standards, with monitoring protocols by which the projects can be evaluated. Strategies for long-term protection and maintenance of the restored ecosystem. Comparison Std. Plan. Rest. PLANNING RESTORATION PLANNING DET. OBJECTIVES ASSESSMENT A clear rational as to why restoration is needed. – Physical,Biological – Chem.,Arch.,Social Interpreting, and Analyzing A statement of the goals and objectives of the restoration project. An ecological description of the site designated for restoration. An ecological description of the reference (see page 8 of PRIMMER multiple sites). Comparison (Cont.) Developing Alternatives Documenting Decisions Explain integration with landscape and its flows of organisms and materials. Explicit plans, schedules, and budgets for site preparation, installation and post installation activities, including a strategy for making prompt mid-course corrections. Comparison (CONT.) Developing Alternatives Documenting Decisions Strategies for longterm protection and maintenance of the restored ecosystem. Comparison (Cont.) Establish Funding and Env. Clearance Implementation Monitoring Well developed and explicitly stated performance standards, with monitoring protocols by which the projects can be evaluated. Workshop Focus Physical Assessment Overlap to Biological Assessment Especially for Riparian Area and Pools Overlap to Water Quality Especially During Construction Precursors to Streambank Accelerated Erosion Watershed Level Conditions Reach Level Conditions Watershed Precursors Excess Sediment Supply, Especially from Landslides, Debris Flow & Debris Torrents (Tillamook Co. Oregon example) Increased Roads, Railroads, & Culverts Decreased Cover Increased Discharge Per Unit Area Large storms (precipitation and duration) Rain on snow and frozen soil Increased precipitation from storm stalling Climate Change Issues Impacting Runoff Dynamic Equilibrium Problem of Excess Supply E.W. Lane, 1955 W/S Excess Sediment Supply Definitions LANDSLIDE--The movement of a mass of rock, debris, or earth down a slope. DEBRIS FLOW--Landslides where a considerable amount of coarse material are suddenly moved by an excessive amount of water and transported in an extremely fast and destructive flow through a valley. DEBRIS TORRENT-- Debris torrents are rapid movements of water charged debris that are confined to steep headwater channels. 2004 Landslide-Debris FlowDebris Torrent Study during 1996-1997 flood season found 9,582 landslides of all types Tillamook County accounted for 836 in the inventory of which 212 were in the Wilson River Watershed and 159 in the Kilchis River Watershed The Little South Fork of Kilchis River had a typical landslide-debris flow- debris torrent in December 2003 Landslide and Debris Flow Landslide Headwall Spheroidal Weathering Residual After Slurry Like Debris Flow Start of Debris Torrent Debris Flow Washed Out Upstream at Start of Debris Torrent See Rounded Boulder >500 feet from Source Downstream of Debris Torrent & Residual Rounded Boulders Down Debris Torrent Debris Flow and Torrent Deposition on Road Offsite Effects 35,000 cubic yards of landslidedebris flow-debris torrent 800 cubic yards into South Fork of Kilchis This sediment moves downstream in pulses Chinook spawning redds impacted Reach Level Precursors Geometry Alteration ( Walla Walla River straightening example) Streambed Alteration (bed excavation like under bridges example Mill Creek Salem ) Creating Headcuts Removal of Native Vegetation (physical, overgrazing, and biological like willow borer) Flow Peak and Duration Increase (cyclic as well as climate change) Walla Walla River,WA Looking Downstream Pre-1964 Channelization football field & track Walla Walla River, WA December 1964 - January 1965 Walla Walla Looking Upst. Dec. 1964 - Jan. 1965 Dynamic Equiibrium Modified By Channelization Qs=Sediment discharge (especially bed-material load), D50= Particle Size, Qw= Flow, S = Stream Slope Walla Walla River, WA December 1964 - January 1965 Down-cutting & Widening for Load, & Meandering for Slope, are the Negative Feedback Mechanism to Return to Dynamic Equilibrium Trout Cr. Deschutes,Co. Trying to Return to Dyn. Equil. Mill Cr. Gravel Removed Under Bridge (initiating downcutting by excavation verses slope caused like in Walla Walla River) At Winter Street 1927 Drawing See Upstream Effects Mill Creek at Winter Bridge x-sect. Mill Creek, Salem (upstream at Summer St.) Wanted to Remove Deposition Bar Mill Creek Salem Mill Creek Salem Mill Creek Drawing Mill Creek Downcutting Along Wall Downstream of Capitol (used to justify bank work) Mill Cr. Island is a Remnant of 1928 Streambed (upstream from 17th St) Remnant of Bed Upstream of Chemeketa St Mill Cr. Headcut to Check Dam (1930 diver. to Mill Race) What Are Reach Causes of Streambank Erosion The reach causes are a combination of fluvial processes, mass failure factors, vegetation factors, biological factors flow factors, and climate factors