An Overview of a Nested Watershed Study in Arctic Alaska

The hydrology of a nest of three watersheds has been studied since 1992 on the North Slope of Alaska, with some additional data collected at individual sites previously. Hydrologic studies of nested watersheds are rare in the circumpolar arctic. Presented here is a comparison of the variability of important runoff-related processes from the headwater foothills to the low gradient, wetland dominated coastal area. Watersheds studied include Imnavait Creek, Upper Kuparuk River and finally the entire Kuparuk River. Also, runoff data from the low gradient Putuligayuk River, measured earlier (1970-1986), is included. Generally, rainfall constitutes 53 to 67 % of the annual precipitation. Most runoff is generated from the foothills; runoff is normally only generated from the coastal plain during snowmelt. Surface storage is an important process on the coastal plain where vertical processes (precipitation and evapotranspiration) are dominant during the summer. Continuous permafrost produces high soil moisture levels except where there are relatively steep slopes with gravity-induced drainage. Snowmelt results in a nearly saturated active layer with summer moisture levels closely allied with summer precipitation. High runoff ratios prevail during snowmelt and rainfall, except for the summer rainfall-generated runoff of the low gradient Putuligayuk River.