RUNOFF GENERATION IN A HIGH BOREAL WETLAND IN NORTHERN CANADA

The stable isotope composition of water and major-ion concentrations w ere measured in a small catchment tributary to Manners Creek, situated in the zone of discontinuous permafrost near Fort Simpson, Northwest Territories. Hydrograph separation calculations based on deltaO-18 and deltaH-2 values of snow, active-layer water, and streamflow reveal th at snowmelt contributions were secondary to active-layer storage contr ibutions throughout the spring freshet period of 1990. At the time of peak spring runoff an estimated 40 to 50 % of streamflow was contribut ed by snowmelt, while over the entire spring period only 25 to 30 % of streamflow was contributed by snowmelt. Overland and pipe flow are sh own to be important mechanisms of rapid snowmelt runoff from permafros t slopes.