HR: 0800h
AN: H21A-0195    [Abstracts]
TI: An Integrated Sediment Budget for the Le Sueur River in Southern Minnesota
AU: * Day, S S
EM: dayxx196@umn.edu
AF: Natioal Center for Earth-surface Dynamics, St Anthony Falls Lab University of Minnesota 2 Third Ave SE, Minnepaolis, MN 55414,
AU: Belmont, P
EM: belmont@umn.edu
AF: Natioal Center for Earth-surface Dynamics, St Anthony Falls Lab University of Minnesota 2 Third Ave SE, Minnepaolis, MN 55414,
AU: Perg, L
EM: lperg@umn.edu
AF: Natioal Center for Earth-surface Dynamics, St Anthony Falls Lab University of Minnesota 2 Third Ave SE, Minnepaolis, MN 55414,
AU: Johnson, A
EM: joh04308@d.umn.edu
AF: Natioal Center for Earth-surface Dynamics, St Anthony Falls Lab University of Minnesota 2 Third Ave SE, Minnepaolis, MN 55414,
AU: Gran, K
EM: kgran@d.umn.edu
AF: Natioal Center for Earth-surface Dynamics, St Anthony Falls Lab University of Minnesota 2 Third Ave SE, Minnepaolis, MN 55414,
AU: Jennings, C
EM: carrie@umn.edu
AF: Minnesota Geological Survey, 2642 University Ave W, St Paul, MN 55114,
AU: Wilcock, P
EM: wilcock@jhu.edu
AF: Natioal Center for Earth-surface Dynamics, St Anthony Falls Lab University of Minnesota 2 Third Ave SE, Minnepaolis, MN 55414,
AB: The Le Sueur River is the primary sediment contributor to the Minnesota River, which is impaired by sediment under the Clean Water Act. The necessary first step toward developing a watershed management plan is identifying sediment sources and sinks throughout the basin. The focus of this study is to quantify the contribution of sediment from different sources in order to understand the broader problems affecting the larger Minnesota Basin. The lower Le Sueur River is actively incising in response to late Pleistocene baselevel fall on the Minnesota River, a result of the catastrophic draining of glacial Lake Agassiz. Potential sediment sources along the Le Sueur include high bluffs composed of highly consolidated Pre-Illinoisian, Illinoisian and Wisconsinin till and alluvial sediment, growing ravines and gullies, sediment exchange between the active channel and floodplains, as well as upland agricultural fields, which account for over 90% of the land surface. We applied side-scanning LiDAR to quantify the amount of sediment being eroded from the high bluffs and banks. To understand meander migration rates as well as ravine and gully retreat rates, and to supplement the understanding of bluff retreat rates, we have used aerial LiDAR along with comparative analysis of historic aerial orthophotos. The aerial LiDAR will also be used to calculate the volume of sediment being stored in the floodplains and terraces along the river, which will be used to create a floodplain exchange model. Preliminary results indicate that bluff retreat rates could be as high as 0.4 meters per year and meander bend migration rates up to 3 meters per year in isolated reaches of the watershed. Data collected from each potential source will be combined to create an overall sediment routing model for the watershed.
DE: 0496 Water quality
DE: 1815 Erosion
DE: 1820 Floodplain dynamics
DE: 1825 Geomorphology: fluvial (1625)
DE: 1855 Remote sensing (1640)
SC: Hydrology [H]
MN: 2007 Fall Meeting