Engineered Logjam Technology: A decade of application and development of science based design guidelines.
Over 11 years ago the first engineered logjams (ELJs) were constructed in the Upper Cowlitz River (Abbe et al 1997). Nine years ago, the North Fork Stillaguamish River project was presented at the 1998 AGU Fall Meeting (Abbe et al 1998). Over the last decade, tribes, governmental agencies, private land owners and non-profit organizations have used ELJs to restore river habitat, limit channel incision, and provide bank protection for property and infrastructure. ELJs have been constructed throughout the Pacific Northwest, Alaska, California and as far away as New South Wales, Australia. The development of ELJ technology was founded on the premise of applying scientific methods to: (1) assess project sites (e.g, hydrology, hydraulics, sediment, vegetation, channel dynamics), (2) understand the mechanics of wood debris, (3) emulate natural processes and forms, (4) adapt solutions to situations constrained by human development (e.g., channelization, flow regulation) and (5) educate human communities about fluvial systems (e.g., address real and perceived views about wood debris and fluvial systems, considering direct and indirect effects on property and public safety). The case for a scientific standard of practice is supported by the successful performance of ELJ projects that employed a scientific analysis of site conditions, structure stability and the hydraulic and channel response to proposed structures. ELJ structures have successfully survived 100-yr flood events; delivered measurable increases in the amount of aquatic habitat, periphyton and invertebrate populations, and floodplain connectivity; created preferential habitat for juvenile salmon; and provided effective bank protection. I summarize the physical performance of several ELJ projects built from 1996 to 2006 and present a general scientific standard of practice for ELJ technology and wood debris management.
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- 0481 Restoration;
- 0744 Rivers (0483;
- 1825 Geomorphology: fluvial (1625)