Use of Large Woody Materials and Large Wood in Streambank Erosion Control

In recent years, woody material has been used to add a habitat component to the use of woody materials for bank protection. However, the use of large woody materials for bank protection has a long history. Use of woody material in stream stabilization is documented in patents issued for spur dikes of trees (1878), tree jetties (1883), pile A-frame jetties (1885), boom of trees (1902), cribs filled with brush (1915), mesh crib (1923), and pile. Early work was done in combination with fascines, brush mattresses, stakes and pole planting which today is called Soil Bioengineering. The Civilian Conservation Corps (CCC) developed many parks along riparian areas in1930's, and used large and small wood in bank stabilization such as along Means Creek in Tongas State Park in Florida ( Ray, 2003). Other early work in the 1930's, is described in Edminster et al, (1949). Soil-bioengineering on streambank side slopes is generally not recommended, unless toe protection is provided, and is very dependent on stream type and stage of channel evolution (Reckendorf and Steffan (2006).

At some unknown time people started using the terms Large Woody Material (LWM) or Large Woody Debris (LWD). The use of those terms has varied from the placement of logs, stumps, and rootwads to whole trees with rootwads and limbs attached (Hopkins, 1999), to portions of trees with or without rootwads (CDEP,2003). Here the LWM definition, will include trees, branches, rootwads, and other large wood , essential for stabilizing the LWM structure, including logs for spacers, or deflectors, and or vertical wood post. Large wood (LW) includes wood structures that only involve logs and or vertical post without rootwads. Large woody debris deposition occurs naturally and when duplicated along streams it is installed with the intent of collecting more LWD and LW. It may be appropriate to use LWD to refer to natural wood accumulation and LWM to refer to installed woody material.

A research and demonstration study in the 1970's done by the Corps of Engineers (1981), and reported on by NRCS (2007), included several field trials using LWM for streambank protection. The California Department of Fish and Game (Flosi, and Reynolds, 1994) improved on the use of LW as bank armor by providing a toe trench with a partially buried log, and then securing all LW with re-bar, metal fence post, and culvert stakes, and cabling back to a deadman or boulder. In the middle 1980's Dave Rosgen (1989), started doing extensive work throughout the US installing rootwads , and logs with boulder buttress. A spacer rootwad or log was installed in a trench, and at a right angle one or more rootwads were installed in a trench that was oriented upstream. The spacer log or rootwad was boulder buttressed, and than the bankfull bench trenches were backfilled. Rosgen referred to these installations as native material bank revetment (Rosgen, 1993).

Rosgen (1993) introduced the concepts of log-vane (LV) for re-direction of streamflow for bank protection, using logs or rootwads. The log-vane is pointed upstream at about a 20 to 30 degree angle to the streambank. The log or rootwad vane, redirects streamflow as the flow crosses the log perpendicularly across the wood structure, and away from the streambank. The log-vane or rootwad vane are secured with boulders. Later versions of log-vanes and rootwad vanes, used reverse rootwads in bankfull bench trenches that are boulder buttressed. The log or rootwad vanes are buttressed at the tip and back adjacent to a bankfull bench. Reckendorf (2007) modified this concept by using an eco-block, chained below the rootwad, near the bankfull bench and below a rock boulder placed on the upstream side of the rootwad (Figures 1 and 2). This modification was necessary to offset buoyancy because the LV's installed in the Pack River and Delta Project, (Reckendorf, 2008) were inundated up to five feet deep in Lake Pend Oreille, after they served their purpose to re-direct flow during spring runoff. Log and rootwad vanes have the effect to create backwater on their upstream side, such that sedimentation can occur adjacent to the streambank, where erosion had formally occurred. Rosgen started building LW cross-vanes in about 1997, which redirect flow away from both streambanks, and keeps the channel thalweg in the center of the river. These are illustrated in Rosgen (2006).

Engineering log jams (ELJ's) for streambank stabilization were first introduced in the early 1990's by Tim Abbe. The application of ELJ's have been discussed by Abbe, and Montgomery, (1996), and Abbe, Montgomery and Petroff (1997). Engineering Log Jams (ELJ's) are patterned after natural log jams, and are usually formed by using several key member rootwads that stabilize and anchor other debris. A toe trench is desirable, although not always provided, (Southerland and Reckendorf, 2008), Large woody material are stacked on key members for ballast. Vertical pilings are usually wood, but steel piles have been used, and are added for stability, and are to be driven below scour depth. The whole structure is backfilled with excavated sediment to provide additional ballast. ELJ's are built with passive (weight and shape of structure are the anchor) or active anchoring (Saldi-Caromile et al, 2004). Active anchors can be flexible or ridge. Rigid anchors are ballast, pilings, cabling or chaining, pinning, deadman anchors, anchoring to rocks, and combinations of above (Saldi-Caromile et al, 2004). An ELJ installed along a stream that is later inundated by a lake so actively anchored with eco-blocks, chain, vertical post and re-bar is represented in Figures 3 (only first two racks), and Figure 4 (Reckendorf, 2008).

Most river restoration stabilization work involves some combination of the techniques mentioned, and most LW and or LWM installations are done in conjunction with soil-bioengineering for treatment above the toe position. Millions of dollars of LW and LWM work has been done in the past 25 years. Federal and State environmental laws and regulations have forced the installations using LW and LWM in combination with soil-bioengineering, to provide a habitat component along rivers that was lost when only rip-rap, gabions or concrete walls were installed.

• Abbe, T., and Montgomery, D. 1996. :Large woody debris jams, channel hydraulics, and habitat formation in large rivers. Regulated Rivers Research and Management 12 pages, 201-212.
• Abbe, T., Montgomery, D., and Petroff, C. 1997. Design of stable in-channel wood debris structures for bank protection and habitat restoration. In S.Y. Wang, . Langendoen and F. D. Shields Jrs. (eds). Management of Landscapes Disturbed by Channel Incision, Stabilization, Rehabilitation, and Restoration, Center for Computational Hydroscience and Engineering, University of Mississippi, 809-815.
• California Department of Public Works (CDPW). 1960. Bank and shore protection in California highway practice. Sacramento, California. 423pp.
• Connecticut Department of Environmental Protection. 2003. Large woody debris fact sheet. Connecticut Department of Environmental Protection, 6pp.
• Flosi, G. and Reynolds, F. 1994. California salmonid stream habitat restoration manual, second edition. California Department of Fish and Game. Sacramento, CA. 271pp.
• Edminster, F. , Alkinson, W., and McIntyre, A. 1949. Streambank erosion control on the Winooski River, Vermont. Report No. 837, USDA, Soil Conservation Service, Washington D.C.
• Natural Resources Conservation Service. 2007. Part 654, Stream Restoration Design Handbook, Technical Supplement 14J. The Use of Large Woody Materials for Habitat and Bank Protection. TS14J1 – TS14J13. Washington D.C.
• Ray, D. 2003. Means Creek below Aspalaga Landing, south of I-10. EcoSummary. Florida Department of Environmental Protection. Tallahassee, FL. 3pp.
• Reckendorf, F. and Steffan, L. 2006. Regional application of stream classification systems in planning and design of stream stabilization projects. ASCE, World Environmental and Water Resources Congress, Omaha, NB. pdf.
• Reckendorf, Frank. 2008. Pack River Delta, erosion and sedimentation. Lake Pend Oreille, Bonner County, Idaho. Reckendorf and Associates Report for Ducks Unlimited. 78pp.
• Rosgen, D. 1989. Short course on river restoration, principles and applications, Sacramento, CA, January 10-11, 1989. Wildland Hydrology, Fort Collins, CO. 138pp.
• Rosgen, D. 1993. Applied fluvial geomorphology. Training Manual. River Short Course, Wildland Hydrology. Pagosa Springs. CO. 450pp.
• Rosgen, D. 2006. Cross-Vane, W-weir, and J-hook. Description, design and application of stream stabilization and river restoration. Wildland Hydrology, Fort Collins, CO. pdf. www.wildlandhydrology.com
• Southerland, B. and Reckendorf, F. 2008. Performance of ELJ,s in Washington State-post project appraisal. River Restoration Northwest Symposium, February 4-7, 2008, Skamania, WA pdf.
• Saldi-Carolmile, K. Bates, K., Skidmore, P,., Barenti, J., and Pineo, D. 2004. Stream handbook restoration guidelines. Prepared for Washington State Aquatic Habitat Guidelines Program. Olympia, WA. www.rrnw.org