The fluvial morphodynamics of two small permafrost drainage basins, Richardson Mountains, Northwestern Canada

Based on hydrological fieldwork in the tundra of northwestern Canada during the springs of 1986, 1990, 1992, and 1994 and the summers of 1998, 1999, and 2000 the paper deals with the fluvial processes induced by spring snowmelt and by summer rainfall in two small stream valleys. At the end of winter the floors of these flat‐bottomed valleys are covered by icings (aufeis) over most of their length. The biggest quantity of meltwater runoff passes in an ice channel on top of the icing, with flow velocities up to 4.8 m/s. The main solid‐sediment transport takes place through the short runoff interval, when the stream channel has entrenched the aufeis in some places. The calculated suspended load transport during snowmelt flood varied from 62–313 t/km2 in different years. In summer, suspended‐sediment transport varies between 0.2–1.4 t/km2. There are no data about the frequency of exceptionally strong precipitation events, similar to those that occurred during the 1999 summer in the Douglas Creek basin that led to a suspended load transport of 153 t/km2 and a bedload transport of 444 t/km2 in about 12 days. The average annual suspended‐sediment yield for Andy Creek is 71 t/km2/yr, and 328 t/km2/yr for Douglas Creek. The average annual solutes yield for Andy Creek is 19 t/km2/yr, and 52 t/km2/yr for Douglas Creek. If one includes the hardly‐recordable bedload transport, the total equivalent surface lowering rate by fluvial solids transport is about 350 mm/1000yr for the Andy Creek basin and 850 mm/1000yr for the Douglas Creek basin. Copyright © 2002 John Wiley & Sons, Ltd.