Water balance dynamics of three small catchments in a Sub-Arctic boreal forest

This study examines the water balance components from three small sub-arctic watersheds near Fairbanks, Alaska, USA, which vary in permafrost coverage from 3 to 53%. The results show that the presence or absence of permafrost affects many of the water balance components, particularly streamflow runoff and groundwater storage. The average annual precipitation is 410 mm, two-thirds of which is rain. Evapotranspiration, derived using the Priestley-Taylor method, averages between approximately 200-310 mm. During the snowmelt and summer runoff periods, the presence of poorly drained permafrost limits infiltration of surface waters, generating higher runoff than in comparable well-drained non-permafrost soils. Lower storm flow, but higher baseflow is consistently observed in the C2 (3% permafrost coverage) and C4 (18% permafrost coverage) sub-basins when compared to the C3 (53% permafrost coverage) sub-basin. In the sub-arctic region, many of the storage processes (subsurface storage, interception, and stream icings) critically important to the water balance are the least well quantified.