Skip to Main Content
Spatial distribution of impacts to channel bed mobility due to flow regulation, Kootenai River, USAAuthor(s): Michael Burke; Klaus Jorde; John M. Buffington; Jeffrey H. Braatne; Rohan Benjakar
Source: In: Proceedings of the Eighth Federal Interagency Sedimentation Conference; 2006 April 2-6; Reno, NV. Washington, DC: U.S. Department of the Interior, U.S. Geological Survey, Advisory Committee on Water Information, U.S. Subcommittee on Sedimentation. 9 p.
Publication Series: Paper (invited, offered, keynote)
Station: Rocky Mountain Research Station
PDF: View PDF (468.78 KB)
DescriptionThe regulated hydrograph of the Kootenai River between Libby Dam and Kootenay Lake has altered the natural flow regime, resulting in a significant decrease in maximum flows (60% net reduction in median 1-day annual maximum, and 77%-84% net reductions in median monthly flows for the historic peak flow months of May and June, respectively). Other key hydrologic characteristics have also been affected, such as the timing of annual extremes, and the frequency and duration of flow pulses. Moreover, Libby Dam has impeded downstream delivery of sediment from the upper 23,300 km2 of a 50,000 km2 watershed. Since completion of the facility in 1974, observed impacts to downstream channel bed and bars in semi-confined and confined reaches of the Kootenai River have included coarsening of the active channel bed, homogenization of the channel bed, disappearance of relatively fine-grained beach bars, and invasion of bar surfaces by perennial vegetative species. These impacts have led to reduced aquatic habitat heterogeneity and reduced abundance of candidate recruitment sites for riparian tree species such as black cottonwood (Populus trichocarpa) and native willows (Salix spp.). Limited quantitative documentation of the pre-regulation substrate composition exists. However, based on the existing evidence assembled by others, we have assumed that the contemporary river bed is relatively coarser than the pre-regulation bed. Making this assumption, we tested the hypothesis that even though the contemporary bed is relatively coarser than the historic bed condition, the pre-regulation hydrograph applied to the contemporary bed would result in ‘regular’ bed movement in most sections of the study reach, while the regulated hydrograph provides limited opportunities for bed and bar adjustment. Our sampling effort to document the contemporary bed composition over a 100-kilometer channel section included stratification of the study reach by reach-scale characteristics, and underwater photography-based methods. We present the results in a spatially-distributed manner that allows evaluation of both local factors and downstream trends in hydrologic alteration through the study reach.
- You may send email to email@example.com to request a hard copy of this publication.
- (Please specify exactly which publication you are requesting and your mailing address.)
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationBurke, Michael; Jorde, Klaus; Buffington, John M.; Braatne, Jeffrey H.; Benjakar, Rohan. 2006. Spatial distribution of impacts to channel bed mobility due to flow regulation, Kootenai River, USA. In: Proceedings of the Eighth Federal Interagency Sedimentation Conference; 2006 April 2-6; Reno, NV. Washington, DC: U.S. Department of the Interior, U.S. Geological Survey, Advisory Committee on Water Information, U.S. Subcommittee on Sedimentation. 9 p.
KeywordsPopulus trichocarpa, Salix, spatial distribution, channel bed movement, flows, Kootenai River
- Temporal effects of mechanical treatment on winter moose browse in south-central Alaska
- Aboveground and belowground mammalian herbivores regulate the demography of deciduous woody species in conifer forests
- Volatile organic compound emmission rates from mixed deciduous and coniferous foest in Northern Wisconsin, USA
XML: View XML