ECOGEOMORPHIC RESPONSE TO STREAM RESTORATION PRACTICES IN AN EXPERIMENTAL MEANDERING STREAM CHANNEL

To develop predictive models of stream physical and ecosystem response to restoration activities requires a fundamental understanding of ecogeomorphic interactions at spatial scales ranging from microbial to reach scale (the scale of restoration activities) and beyond; however, components of natural systems such as vegetation, macroinvertebrates and fish, and ecological processes dependent on local physical stream channel morphology are difficult or impossible to scale. The Outdoor StreamLab (OSL) at the St. Anthony Falls Laboratory (SAFL) provides a unique opportunity to take laboratory-scale measurements into a full-scale outdoor setting. Because both water and sediment feed can be controlled, this facility provides the means to conduct controlled experiments incorporating processes such as interactions between flow, vegetation, and biota that cannot be captured in an indoor flume. The Riparian Basin of the OSL is a 40 m by 20 m experimental area currently configured into a vegetated floodplain with a small sand-bed meandering stream (average bankfull width, 2.7 m; average bankfull depth, 0.3 m; sinuosity, 1.3) that has been flowing year-round since June 19, 2008. This system, fed by Mississippi River water, is capable of a wide range of flows from baseflow (44 L/s) to large overbank floods (1200 L/s) enabling controlled full-scale experiments on the physical, chemical, and biological interactions among a channel, its floodplain, and vegetation. A recent set of OSL experiments examining flow fields, sediment transport, and nutrient dynamics in the vicinity of in-stream rock structures demonstrates the capability of full-scale experiments, coupled with indoor, field, and numerical investigations, to provide insight on the complex interactions between physical, chemical, and biological ecogeomorphic processes.