Infrastructure impacts on circulation in Lake Champlain

Session: Hydraulics, Hydrology, and Human Interactions in the Lake Champlain/Richelieu River Basin

Liv Herdman, USGS, [email protected]
Thomas Manley, Middlebury College, Dept. of Geology, [email protected]
Peter Mehler, Middlebury College, [email protected]

Abstract

Humans living adjacent to waterways often develop infrastructure such as ports, piers, or bridges that can alter the circulation patterns of the water body. At the height of the American railroad industry several causeways were constructed between narrow openings and across shallow regions of Lake Champlain in order to connect railroads. The causeways primarily cross the eastern side of the lake, often referred to as the “Restricted Arm”. To investigate how the causeways alter the already restricted circulation in the eastern side of the lake, a hydrodynamic model was built using Deltares Flow Flexible Mesh (DFLOW-FM). The model was calibrated using velocity, temperature, and water level data  collected in 1993 and 2015. The model was forced with adjusted discharges from USGS gage stations and weather observations made at 4 locations on and adjacent to the lake. The model was run to simulate the circulation over the ice free season in 2017 with different scenarios of causeway removal; including the extremes of all causeways staying in place and all being removed. We found that causeway removal causes significantly more exchange through the openings and that the changes are associated with a change in motions with a period of ~8-12 hours.