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

摘要

The model bankfull discharge recurrence interval (annual series) (T_a) in streams has been approximated at a 1.5-year flow event. This study tests the linkage between regional factors (climate, physiography, and ecoregion) and the frequency of bank- full discharge events in the Pacific Northwese (PNW). Patterns of Ta were found to be significant when stratified by EPA Ecoregion. The mean value for T_a in the PNW is 1.4 years; however, when the Data is stratified by ecoregion, the humid areas of western Oregon And Washington have a mean value of 1.2 years, while the dryer Areas of Idaho and eastern Oregon and Washington have a mean Value of 1.4 to 1.5 years.