IJC invites public comment on draft flood forecasting and mapping report for Lake Champlain and Richelieu River and previews flood inundation maps

The International Joint Commission (IJC) is requesting comments from the public on a draft report to enhance flood preparedness and warnings for Lake Champlain and the Richelieu River by December 10, 2015.  Specifically the IJC asks if the report’s recommendations are sound and whether the recommendations address real needs for enhanced flood preparedness and warnings for Lake Champlain and the Richelieu River. 

The Commission is also inviting the public to preview the associated flood inundation maps.

Following the submission of IJC’s  July 2013 Plan of Study “The Identification of Measures to Mitigate Flooding and the Impacts of Flooding of Lake Champlain and Richelieu River” (POS), the governments of the United States and Canada asked the IJC to address two issues associated with the system wide flooding in 2011:

a.    closing the gaps in the data needed for a future real-time flood forecasting and inundation mapping system, and

b.    the creation of static flood inundation map products. 

The IJC appointed the International Lake Champlain-Richelieu River Technical Working Group (TWG) comprised of technical experts from United States, Canada, Quebec, Vermont, and New York to address the two issues. The IJC is now inviting public comment on the TWG’s draft report Toward an operational real-time flood forecasting and flood inundation mapping system for the Lake Champlain and Richelieu River.

The TWG report includes six recommendations addressing the need to: 

1.    Implement an operational probabilistic approach for forecasting floods, including modelling of wind set up and wave action;  

2.    Keep the Henry and Grand Isle water level station to maintain water level calibration and also install wave buoys to assist in wave model calibration;

3.    Institute a binational coordination body such as an IJC Board to support agencies involved in real time forecasting;

4.    Acquire new bathymetric data for the Richelieu River between Sorel and Saint-Jean-sur-Richelieu; 

5.    Create a single consistent Digital Elevation Model (DEM) for the entire Lake Champlain-Richelieu River basin following the completion and quality control of LiDAR and bathymetric data acquisition; and 

6.    Generate static flood inundation maps for the entire Lake Champlain Richelieu River system.  

The current effort has significantly advanced the creation of flood-inundation maps for the Lake Champlain-Richelieu River system. These maps provide an emergency planning tool for authorities and the general public on land that may flood during high water events. Static inundation maps were created for the Vermont side of Lake Champlain and a portion of the New York northeastern shoreline on the US side, and for the Richelieu River from the border to downstream of the Fryers Rapids on the Canadian side. A preview of these maps is available on the IJC web site at: http://arcg.is/1MhXui2, however, the site is under construction and the text accompanying the maps is in French only at this time. A complete LiDAR Digital Elevation Model available in Canada also allowed for the representation of inundation depths for the 11 flood scenarios.  The inundation maps are not designed for regulatory purposes, but rather to show flooding potential under different conditions.  Furthermore the report does not evaluate potential flood mitigation measures as this was outside of the scope of the reference from governments. 

This public comment period is being held from November 16 to December 10, at which time the IJC will consider public comments before submitting its final report to governments. 

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