USA

The Arctic fresh water hydrological cycle is dominated by the melting of the seasonal snow cover and scattered precipitation events during the summer months. Predicting and characterizing potential hydrological response is an important component for engineering infrastructure for the appropriate climatic conditions. A semi-distributed Swedish conceptual model, HBV, has been applied to the Imnavait basin, located in the headwaters of the Kuparuk River on the North Slope of Alaska, to examine runoff during spring and summer months. The methodology began by analyzing the long-term climatic records of the Imnavait basin from 1986 to present. Initial calibration work was completed in both spring and summer periods using the Monte Carlo technique; one set from each period was selected and used in the complete version of HBV. The model was recalibrated from 1988 to 2002 and then validated against the 2003 to 2008 time frame. The overall model performance was adequate for engineering purposes, with the best results when the input precipitation was accurate in terms of timing and magnitude. Differences between observed and modeled results included the impact of snow-damming and evaporation during the spring, while convective storms and melting of basal ice in the active layer distorted the summer period.