Determination of lateral inflows in the Kuparuk River watershed, a study in the Alaskan Arctic

Abstract

The objectives of this research were to investigate the relationships between lateral inflows and watershed characteristics within the Kuparuk watershed of Arctic Alaska, as well as to quantify the lateral inflows to be used as an input for calibrating and running a process-based instream water temperature model. Determination of lateral inflows was accomplished by constructing hydrographs at multiple locations along Imnavait Creek and the Kuparuk River using stage and discharge field measurements. The hydrographs were then routed between gauging stations downstream (starting upstream) using the Muskingum routing method; and finally subtracting the routed hydrograph from the downstream measured hydrograph to calculate any additional water that had entered the reach between gauging stations. Results showed, as a general trend, that reaches within the northern foothills of the Brooks Range experienced larger lateral inflow contributions per square kilometer and had larger runoff ratios than subsequent reaches to the north where the terrain flattens out and transitions into the coastal plain. Two reaches within the watershed contradicted the general trend. The low-gradient reach nearest to the Arctic Ocean experienced larger lateral inflows throughout the summer that were unaffected by rainfall precipitation events; this is believed to be caused by snowmelt water initially stored in the low gradient terrain and slowly released into the drainage network during summer months. This area is rich with wetlands, ponds, and lakes and snow-damming during break up is prevalent. The other reach was located upstream of the Kuparuk aufeis field and was observed to lose water during the summer of 2013, supporting a hypothesis that the aufeis formation in this area is fed throughout the winter by a large talik upstream.