Minnesota Water Resources Conference - Water Resources Center ...

BOOK OF ABSTRACTS
Tuesday, Monday, October 27 23
Concurrent Sessions II 1:15–2:45
Track D: Stream Erosion
Estimation of Nutrient Loads from Streams Affected by Agriculture Land Retirement Using Continuous
Monitoring and Laboratory Concentrations
Victoria Christensen, U.S. Geological Survey, vglenn@usgs.gov
The U.S. Geological Survey, Minnesota Board of Water and Soil Resources, and the Legislative-Citizen
Commission on Minnesota Resources conducted a study to describe the water quality of three Minnesota
River sub-basins. Water-quality and aquatic-biology monitoring at Chetomba Creek, West Fork Beaver Creek,
and South Branch Rush River was conducted from October 2005 through September 2008. Water quality
was described using multi-parameter water-quality sondes that measured specific conductance, pH, water
temperature, dissolved oxygen, and turbidity. Surrogate relations were developed between the sonde parameters
and nutrient concentrations from laboratory analyses. The result was a continuous record of estimated nutrient
concentrations and loads, that can be used to monitor the effects of agricultural land-retirement programs
and large-scale best management practices (BMPs) on streams. Continuous loads can be used by resource
managers to evaluate the success of agricultural BMPs and land-retirement programs and to indicate which
sub-basins to concentrate efforts for improving stream quality.
Using Current Knowledge of River Channel Processes to Predict the Equilibrium Topography of a Sand-
Bed Channel
Jeff Marr, University of Minnesota, marrx003@umn.edu; Anne Lightbody, University of Minnesota; Chris Paola, University of
Minnesota
Stream restoration projects often seek to improve physical properties and rehabilitate ecological processes
of a channel; however, project designs are often based on limited scientific knowledge. In the long term, a
river within an alluvial flood plain will sculpt its banks to create a dynamically stable equilibrium (that is,
although any position along the channel may change, the channel’s mean properties will remain constant).
Observations from natural rivers therefore allow the estimation of the stable equilibrium for a restored stream
with known hydrology and bed material. Here, we present a design for a small sinuous sand-bed channel based
on fundamental knowledge of equilibrium channel processes. Important parameters include the sediment size
distribution; mean bankfull discharge, width, and depth; the variability in bankfull width and depth; and the
baseflow depth. The channel design was compared to a reference reach with the same discharge and median
grain size. To determine whether the equilibrium topography was predicted correctly, this channel design
was created within the St. Anthony Falls Laboratory’s Outdoor StreamLab during the summer of 2008, and its
response to perturbation ( floods) was assessed.
Minnesota Water Resources Conference, October 27–28, 20078 28