BANKFULL DISCHARGE RECURRENCE INTERVALS AND REGIONAL HYDRAULIC GEOMETRY RELATIONSHIPS: PATTERNS IN THE PACIFIC NORTHWEST, USA

• Published in: Journal of the American Water Resources Association Vol. 37; no. 5; pp. 1249 - 1262
• Main Authors: Castro, Janine M., Jackson, Philip L.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.10.2001; American Water Resources Association
• Subjects: bankfull discharge recurrence interval; channel-forming flow; Earth sciences; Earth, ocean, space; ecoregion; Exact sciences and technology; hydraulic geometry; hydraulics; Hydrology; Hydrology. Hydrogeology; regional curves; surface water hydrology; Oregon; United States; Idaho; Washington; USA, Oregon; USA, Idaho; USA, Washington; hydrology; atmospheric precipitation; streams; vegetation; climate; velocity; North America; frequency; surface water; hydraulics; channels; discharge; drainage; geometry; annual average
• ISSN: 1093-474X; 1752-1688
• DOI: 10.1111/j.1752-1688.2001.tb03636.x

Bankfull is defined as the stream level corresponding to the discharge at which channel maintenance is most effective. Research has suggested that the annual series bankfull discharge recurrence intervals (T sub(a)) are approximately equal to a 1.5-yr event, but the data have suggested also that there is a link between stream channel type and T sub(a). To examine this linkage on a regional scale, data were collected on 76 streams in the Pacific Northwest region of the US during the summer of 1995. Bankfull discharge, cross-sectional area, width, depth, and drainage area were used as variables to generate regional regression equations for various regions within the Pacific Northwest. Ecoregion Classifications were used to divide the area into regional units that included areas of similar geology, topography, climate, vegetation, soils, and major land uses. Results revealed that the average T sub(a) for the entire area was 1.4 yr. The data indicated that the average T sub(a) of streams could be predicted for different regions based on vegetative and climatic similarities.