Experimental Approach for Estimating Daily Water Residence Time in Great Lakes Rivermouths

Session: 59. - Innovative Monitoring across the Great Lakes

Faith Fitzpatrick, U.S. Geological Survey, [email protected]
Paul Reneau, USGS Wisconsin, [email protected]
Stephen Westenbroek, U.S. Geological Survey, [email protected]
James Blount, U.S. Geological Survey, [email protected]

Abstract

Describing short-term variations in water residence time in Great Lakes rivermouths, especially during summer months, is important for understanding how nutrient and sediment fluxes from tributaries affect algal blooms and aquatic habitats in nearshore environments.  Continuous velocity data from a U.S. Geological Survey index velocity station and synoptic velocity data from longitudinal transects were used in the development of an empirical model for mean daily water residence time for the lower Fox River, Wisconsin. Mean daily residence times from April through October 2016 ranged from about 10 to 80 hours depending on the interaction of Fox River inflows with seiche related water-level oscillations in Green Bay. Frequent water-level oscillations, ranging from 4 to 10 times a day, caused reverse velocities along the entire 12-km length, especially during low river inflows. A large oscillation in September 2016 transported water more than 1 km upriver before reversing to the downriver direction. This approach has potential to be applied at other Great Lakes rivermouths with index velocity stations. 

1. Keyword
tributaries

2. Keyword
estuaries

3. Keyword
hydrodynamics

4. Additional Keyword
Green Bay

5. Additional Keyword
water currents

6. Additional Keyword
tributary-lake