| Summary: | Climate change effects are strongly manifested in the Arctic. Understanding the mechanisms that link climate to river temperature is critical for predicting the impact that climate change will have on aquatic species distribution, carbon cycling, and climate change feedback mechanisms as river temperature exerts direct control over biological, physical, and chemical processes in the aquatic environment. We present the results from a basic dynamic stream temperature model for the Kuparuk River in Arctic Alaska. This model is used to determine and quantify mechanisms that control river temperature and to identify additional mechanisms necessary to capture Arctic river temperature regimes. This basic model accounts for heat exchange between the river and the atmosphere, river bed, and landscape through lateral inflows (combined surface and subsurface flow). The watershed was divided into headwater (lower order) and coastal (higher order) sections to determine spatial variability in dominant mechanisms. Due to the complexity of lateral inflows and minimal information on the spatial and temporal variability of volumes and temperatures, different simplified treatments were tested within the model. Based on two years of data and subsequent modeling, this basic model reproduced the thermal behavior in the coastal portion of the study reach, but not in the headwater regions. It is expected that due to smaller volumes of water in the lower order portions of the watershed, it is necessary to have more detailed information on channel morphology to capture the variability of surface areas with the highly transient flow regime. Further, additional heat transfer mechanisms such as surface and hyporheic transient storage may be necessary to capture temperature responses during low flow periods.
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