The Influence of Lateral Inflows in Arctic Beaded Streams

Lateral inflows in beaded arctic streams influence water residence times, temperature responses, and nutrient export. To date there is minimal understanding regarding the quantity of lateral inputs and their influence on overall energy and mass budgets. To progress this understanding, flow data were collected in the upper and lower extents of a 40 m study reach in Imnavait Creek, Alaska. Differences in flows were used to estimate total lateral inflows. Simultaneously, ground and surface water conditions were monitored using conductivity, temperature, and depth sensors to estimate the percent of lateral inflows attributed to groundwater flow. Combined, these data illustrate that these streams receive significant gains from lateral inflows (~1.5% of the total flow) over short stream lengths. A large portion of these gains are due to surface runoff, however, it was found that ~5% of each beaded pool volume is replaced daily by groundwater inputs. This cooler water plunges to pool bottoms and enhances thermal stratification up to 13°C within each pool. Such strong thermal stratification reduces mixing and leads to anoxic conditions in the pool bottom. This influences the timing and magnitude of nutrient export from the landscape by altering both physical and chemical processing. Funding for this research was provided by the National Science Foundation, project numbers NSF-ARC 1204220, NSF-ARC 1204216, and Arctic LTER/NSF-DEB 1026843