Reinert Huseby Karlsen

Hydrological response to changing climate conditions: Spatial streamflow variability in the boreal region

In this paper we combined a multi-model ensemble based on 15 regional climate models with a multi-catchment approach to explore the hydrologic sensitivity of 14 neighboring and rather similar catch ...

Landscape controls on spatiotemporal discharge variability in a boreal catchment

Improving the understanding of how stream flow dynamics are influenced by landscape characteristics, such as soils, vegetation and terrain, is a central endeavor of catchment hydrology. Here we inv ...

Decoupling of carbon dioxide and dissolved organic carbon in boreal headwater streams

Streams and rivers emit large quantities of carbon dioxide (CO2) to the atmosphere. The sources of this CO2 are in-stream mineralization of organic carbon (OC) and CO2 input via groundwater inflow but their relative importance is largely unknown. In this study, we quantified the role of in-stream OC mineralization as a source of CO2 in a number of nested boreal headwater streams. The results showed that mineralization of stream OC contributed 3% of CO2 supersaturation at timescales comparable to the estimated water travel times in the streams (<24 hours). Mass balances showed that downstream losses of OC were ≤3% in low order streams whereas up to 16% of the OC was lost in the largest (4th order) streams. In contrast, 85% of the CO2 was lost along the stream network (longest total stream length = 17 km). Under the assumption that in-stream OC mineralization was the main source of stream CO2, higher rates of OC mineralization (6% of OC) than those reported across the literature (≤0.7% of OC) would be required to sustain observed CO2 supersaturation. Further, model results indicated that groundwater inflows were sufficient to sustain observed stream CO2 concentrations. We hence conclude that in-stream OC mineralization was a minor source of CO2 in these boreal headwater systems and that the main source of stream CO2 was inflowing groundwater transporting CO2 originating from soil respiration.