|Thursday, June 03|
Gestion du St-Laurent par la CMI
* Pierre Béland, CMI, Canada
An Adaptive Management Approach to Supporting Great Lakes St. Lawrence River Outflow Management
* Wendy Leger, Environment and Climate Change Canada, Canada
Mike Shantz, Canada
When water levels on the Great Lakes are extremely high, as they were on Lake Ontario and the St. Lawrence River in 2017 and 2019, flooding and other coastal impacts cannot be avoided. The recent and persistent extreme high water levels have led to considerable interest in the regulation of outflows from Lake Ontario. Water released from Lake Ontario through the Moses-Saunders dam on the St. Lawrence River is regulated in accordance with Plan 2014, a set of rules established by the International Joint Commission (IJC). Plan 2014 was selected in 2016 after years of study and stakeholder input to gather data and build tools and models to test various alternative regulation plans. As a part of the implementation of the new regulation plan, the IJC and Governments of Canada and the United States agreed to monitor water level impacts and if not consistent with the model projections, to improve the models to reflect the new data. This is an example of what is known as adaptive management - a structured, iterative process that compares observed (monitored) outcomes to simulated results to improve the models and assess the current and on-going performance of the regulation plans and examines ways to improve outcomes. The Great Lakes and St. Lawrence River Adaptive Management Committee (GLAM) was created by the IJC to guide the adaptive management process. While recognizing that no regulation plan can eliminate impacts under extreme water supply conditions, the IJC is looking to the GLAM Committee to carry out an expedited review of Plan 2014 with the goal of further moderating flooding during extremes. This presentation will discuss the GLAM Committee’s adaptive management approach to gathering information on the socio-economic and environmental impacts experienced along the shorelines of Lake Ontario and the St. Lawrence River in 2017 and 2019 as well as how that information supports decisions by the IJC on how best to regulate outflows during extremes.
Characterizing Vulnerability to High Water Conditions Along the Lake Ontario and Upper St. Lawrence River Shoreline
* Mike Shantz, Environment and Climate Change Canada, Canada
In both 2017 and 2019, water levels on Lake Ontario and the upper St. Lawrence River reached record highs, contributing to significant flooding and erosion impacts to individuals and communities along the shoreline. While some of these local impacts were well documented, there remains a gap in developing a consolidated and consistent assessment of impacts and vulnerability to different water level conditions for broader stretches of the shoreline. As part of the International Joint Commission’s (IJC’s) ongoing effort to assess its outflow management strategy for Lake Ontario, the IJC’s Great Lakes – St. Lawrence River Adaptive Management (GLAM) Committee is working to develop a broad assessment of shoreline vulnerability to different water level conditions. The work builds off of previous modelling and data collection efforts by the IJC while incorporating new information from observed impacts in recent years. The ability to develop predictive approaches for assessing shoreline risk is scale and data dependent. In the short-term, the GLAM Committee is piecing together relevant (and sometimes incomplete) information and testing possible approaches for improved modelling. The activities will support immediate operational requirements related to managing Lake Ontario outflows while providing useful data and a possible framework needed to develop better predictive models of potential impacts under a range of water level conditions and over broad stretches of shoreline.
Collaborative efforts to improve flow and water level forecasting in support of decision making in the Lake Ontario St. Lawrence River system
* Jacob Bruxer, Environment and Climate Change Canada, Canada
Yin Fan, Canada
Natalie Gervasi, Canada
Jamie Ferguson, Canada
Vincent Fortin, Canada
Étienne Gaborit, Canada
Dorothy Durnfor, Canada
Khanh-Hung Lam, Canada
Record-high water levels across the Great Lakes - St. Lawrence River system in 2019 resulted in unprecedented flooding, shoreline erosion and other high water impacts. For Lake Ontario and the St. Lawrence River, this was the second severe high-water event in three years, raising questions in both Canada and the U.S. about the causes of recent events, concerns that they may occur again in the future, and a search for potential solutions. The Environment and Climate Change Canada ECCC), National Hydrologic Service (NHS), provides engineering and technical support to the International Joint Commission and its bi-national Great Lakes Boards responsible for regulating outflows from Lake Superior and Lake Ontario. As part of these responsibilities, NHS staff produce bi-nationally coordinated Great Lakes water level forecasts extending out six months. In the past, inputs to these probabilistic seasonal forecasts were largely based on climatology. However, since 2017, through ongoing collaborative efforts with ECCC’s Meteorological Research Division and the Canadian Centre for Meteorological and Environmental Prediction, 1- to 4-week deterministic and ensemble forecasts of water supplies and other hydrologic input variables are now employed as model guidance to inform weekly forecasts for Lake Ontario and the St. Lawrence River. This has resulted in improved forecast performance, particularly during severe events. Recently, these improved forecasts have been used to help better inform decision makers responsible for regulating outflows, contributing to small, but meaningful improvement in outcomes for multiple interests in the Lake Ontario – St. Lawrence River system.