Nemadji River (Minnesota / Wisconsin)
Project Status: modeling
River Basin Characteristics
The Nemadji River Basin is located just south of Duluth straddling the Minnesota-Wisconsin
border. Of the 433 square miles (277,400 acres) of drainage area that make
up the Basin, approximately 60% of the watershed lies in Minnesota and 40%
in Wisconsin. The watershed includes portions of Carleton, Pine, and Douglas
Counties. 69% of the land cover within the Basin is forested lands, 18% is
cropland and pasture, 11% is wetlands and lakes, and 2% are other categories.
Flows from the Nemadji River enter Superior Bay at Superior, Wisconsin, and
then enter Lake Superior through the Superior Entry navigation channel.
Approximately one third of the basin is comprised of glacial till and glacial
lake-laid clay soils. These soils are commonly referred to as "red clay"
and were formed during the last glaciation of the area some 10,000 years ago.
Red clay is considered highly erodible and is prone to extensive mass wasting
through "slumping" along streams and tributaries. The upland two
thirds of the basin is sandy and loamy tills and glacial outwash. These soils
are generally sandier and much less erodible than red clay.
Source: Executive Summary Report: Erosion and Sedimentation in the Nemadji
River Basin, Nemadji River Basin Project, Natural Resources Conservation Service,
U.S. Forest Service, January, 1998.
Stream bank erosion, which occurs predominantly in the red clay soil areas,
was found to amount to 89% of the total sediment load delivered to the mouth
of the river. As part of the NRCS' Nemadji River Basin Project (NRBP), a comprehensive
sediment budget was developed and calibrated for the existing conditions based
on detailed information for the Skunk Creek sub-watershed. The Skunk Creek
sub-watershed consists of 6,620 acres located in Carlton County, Minnesota,
within the western, central part of the Nemadji River watershed. This sediment
budget has provided valuable information in developing an understanding of
the sediment loading characteristics for the Nemadji River Basin. However,
the sediment budget, in its present form, does not represent a tool which
can be used to assess the impact of best management practices for erosion
control in the watershed.
The primary objective of the Tributary Modeling project for the Nemadji River
was to extend the sediment budget work of the NRBP by introducing process-based
numerical models linked to GIS to describe in detail the Skunk Creek sub-watershed.
The primary tasks of this project were to implement hydrologic, hydrodynamic,
and sediment transport models based on the available data for Skunk Creek.
These models operate within a GIS system and have provided an improved definition
of the stream bank erosion processes within the watershed.
The harvesting of forested lands was also modeled to determine the effects
on sedimentation. The Nemadji Sediment Transport Modeling (NSTM) system
was created using ArcView GIS, MIKE11 (hydrologic model and hydrodynamic model)
and a customized sediment transport model.
USDA Natural Resources
Dr. Mark Riedel
Use and Applications
Upon completion of the tributary model for the Nemadji River, a technology
transfer workshop was held in Duluth, Minnesota, in September 2000 to train
potential users of the model. At this time, the model and database were transferred
to the Carlton County Soil and Water Conservation District in Duluth.
This model has since been used to assess the impacts of forest harvesting
and different land use scenarios within the Nemadji River Basin, model flood
predictions for storm events, and to assess plans to reduce sediment load
to Lake Superior.
more informationor to obtain digital data for advanced modeling
James P. Selegean, P.E., Ph.D.
Great Lakes Hydraulics and Hydrology Office
U.S. Army Corps of Engineers
477 Michigan Avenue
Detroit, MI 48226
Office: (313) 226-6791
Fax: (313) 226-2398