HR: 1340h
AN: H43A-0369    [Abstracts]
TI: Numerical modeling of interactions between lake level head difference, river hydrodynamics and bathymetric change in the St. Clair River
AU: Lu, Q
EM: qlu@baird.com
AF: W.F. Baird & Associates Coastal Engineers Ltd., 627 Lyons Lane Suite 200, Oakville, ON L6J 5Z7 Canada
AU: * Brunton, A
EM: abrunton@baird.com
AF: W.F. Baird & Associates Coastal Engineers Ltd., 627 Lyons Lane Suite 200, Oakville, ON L6J 5Z7 Canada
AU: Nairn, R
EM: rnairn@baird.com
AF: W.F. Baird & Associates Coastal Engineers Ltd., 627 Lyons Lane Suite 200, Oakville, ON L6J 5Z7 Canada
AU: Duckett, F
EM: fduckett@baird.com
AF: W.F. Baird & Associates Coastal Engineers Ltd., 627 Lyons Lane Suite 200, Oakville, ON L6J 5Z7 Canada
AB: The recorded drop in the difference between lake levels on Lake Huron and Lake St. Clair, and possible relationships to historical changes in the flow regime of the St. Clair River is investigated. An evaluation of the possible causes of lake level change included consideration of tectonic uplift, net basin supply change, channel bed scour and sedimentation, and changes to flow through the St. Clair River (changes in hydraulic geometry, ice, vegetation, scour due to ships, exposure of underlying erodible material). Numerical modeling was performed to assess the interactions between historical bathymetric change on river flows the in St. Clair River. The RMA2 hydrodynamic model developed by the U.S. Army Corps of Engineers was used for this investigation. The model was calibrated against stage and flow measurements in the river. Two sets of historical bathymetric data for the St. Clair River (1948 and 2000) were used for modeling runs. The model had open boundaries at the upstream and downstream limits, and both were controlled by lake levels. Various model scenarios were tested to investigate the impacts of bathymetric change and lake level head difference change on river flow patterns and vice-versa. The model output indicates that there has been a significant increase in conveyance throughout the 20th century, which may at least partly explain a drop in head difference between the lakes. Changes to river cross-section (in the last 50 years) have contributed to the acknowledged ongoing decline in the head difference between Lakes Huron-Michigan and St. Clair-Erie, whilst changes in net basin supply have contributed to discharge fluctuations in the river channel. The interactions and feedbacks between these different factors are discussed.
DE: 1815 Erosion and sedimentation
DE: 1824 Geomorphology (1625)
DE: 1860 Runoff and streamflow
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting