Impact of Decreasing Lake Water Levels on Georgian Bay Wetlands

Partners: NASA, Georgian Bay Forever, Great Lakes St. Lawrence Cities Initiative, and the Ontario Ministry of the Environment

A dock sitting on land is a very visible problem that was common during the extreme low water of a couple years ago. It's harder to assess the impact on wetlands from high water to extreme low water over time. NASA's eyes in the sky helped to provide necessary data to assess the impact to Georgian Bay wetlands from highs of 1987 to lows of 2013. To get an overview of the report - the need, the process, and its conclusion - please read the following:

What was the purpose for Georgian Bay Forever?

  • To see how wetland extent changes over time with declining water levels in Georgian Bay
  • To educate policy makers who design and implement wetland protection strategies
  • To create a template process that can be used to develop more maps, for more years in order to advance understanding in how wetlands react to different environmental conditions
  • Work with partners to find a cost effective methodology to measure wetland extent

What was the purpose for NASA?

  • NASA's DEVELOP National Program allows students and new professionals to do research under the supervision of senior scientists. The research seeks to address real environmental issues using NASA's earth observations.
  • To develop a land classification maps process for Georgian Bay and Lake Ontario that could be used for other parts of the Great Lakes in the future

Why do we need to care about wetland reaction to declining water levels in Georgian Bay?

Half the worlds wetlands have been lost since 1900 (UNwater), mostly due to human disturbance. Other research indicates far greater losses. What is not known is the impact of lowering water levels due to climate change. While water levels in Georgian Bay fluctuate for a variety of reasons, the outlook is increasing variability and flashiness with a slight trend to higher average levels and wider range between highs and lows.

Lowered water levels over time can strand and destroy areas of wetland. Georgian Bay Forever (GBF) wanted to know the impact to the relatively pristine Georgian Bay wetlands that play such a critical role in its health. "Wetlands are the transition zones between terrestrial and aquatic ecosystems and provide important ecological and economic benefits." (NASA DEVELOP, Adams and others, page 3). To provide an economic perspective, background research in the NASA DEVELOP report found that experts in the field calculated that "Great Lakes wetlands have been estimated to provide over $10,000 USD per acre in economic and ecosystem services." GBF and many other scientists argue that an economic value cannot be assessed on the habitat of plants and animals who have a natural right to exist. It is clear either way that we should all be aware of the important role of wetlands, which includes these functions:

  • Fish habitat - Many fish communities depend on the coastal wetlands for forage, refuge, spawning, and as a nursery area.
  • Acts as groundwater recharge points - A great explanation from compares wetlands to a giant sponge which sucks up waters and helps to return waters during dryer points.
  • Performs a type of water treatment function - Filters sentiments as well as contaminants such as pesticides from the air and water, which helps to control water pollution. Wetlands filter excess nutrients, reducing harmful concentrations of phosphorus and nitrogen.
  • Protects shorelines- Wetlands can help control flooding and erosion of shorelines by distributing water over a wider area and reducing its velocity.
  • Habitat for numerous species - The Great lakes support more than 3,500 different species, 80% of which rely upon Georgian's Bay coastal wetlands. Wetlands are nesting, feeding and staging grounds for several species of waterfowl and other wildlife such as reptiles and amphibians, and also for many species at risk. According to research sourced for the NASA DEVELOP Report (Adams and others, page 2), maximum species diversity is best achieved with water oscillations that consist of short periods of high water followed by short periods of low water levels.
  • Globally , wetlands act as natural carbon sinks - loosely defined as absorbing more carbon then emitting it.
  • Source of tourism - bird watching, fishing, and canoeing among other recreational activities

How did NASA use views from space to determine wetland extent in Georgian Bay from 1987 and 2013?

Complex and sophisticated equipment and methodologies were used by the NASA DEVELOP National Program team to investigate changing water levels on wetlands in a cost-effective way.

Summary of Process - Monitoring the change in wetlands from high to low for Georgian Bay

  • The time periods of May 1987 (represent the high), and June 2013 (represent the low) were selected as the initial study times
  • Terra Advances Spaceborne Thermal Emission and Reflectional Radiometer (ASTER) provided digital elevation model (DEM) Data to calculate slope which was important for additional land classification accuracy
  • Jason-1 radar alitmeters/NASA'S Topography Experiment (TOPEX/Poseidon) and Jason-2 radar altimeter/Ocean Surface Topography Mission (OSTM) were compared and used in combination with available in situ (in location) water gauge data to track water levels over time
  • Satellite imagery from the Thematic Mapper (TM) on board Landsat 5, Operational Land Imager (OLI) on board Landsat 8, and Thermal Infrared sensors (TIRS) were used in combination with a supervised classification method known as "Random Forest Model". These tools were used to make land cover maps for 1987 and 2013 that demarcated areas of wetlands and non-wetlands.
  • The team identified any changes between the two years, and created a report on the details of the process and the outcomes

The Results and Future Steps

The Results

The Georgian Bay extent change maps show that there was a 10.8% loss of wetlands around the southern portion of the region, while the northern portion of the region had an increase of 7.0% in wetlands extent from 1987 to 2013.

A net loss of 3.8% doesn't sound significant - why does it matter?

The shifting of wetlands has impacts for those geographic regions. People often wonder for example, where have the fish gone that they historically remember in their area? For Southern Georgian Bay, the 10.8% loss is significant for the economic and ecosystems services that wetlands provide for that area. As stated earlier, wetlands provide important roles for fish, groundwater recharging, water quality, shoreline protection, habitat for numerous species, and help with carbon control.

Full report

Future steps

  • Mapping Protocol - The DEVELOP team created a protocol that can assist other regions of the Great Lakes in mapping wetlands.
  • More study times - Include more years between to identify the changes in response to the fluctuating water levels of Georgian Bay.
  • Other locations - Explore the possibility of transferring the methods used in this project to other locations around the Great Lakes.

Sources used on this page

Adams, Emily; Del Valle Martinez, Idamis; Harris, Miriam; Zimmerman, Stephen; Ross, Dr. Kenton. "Great Lakes Climate II. Impact of Decreasing Water Levels on Great Lakes Wetlands". NASA DEVELOP National Program. Langely Research Center. Spring 2015. Retrieved December 28, 2015 from

Adams, Emily; Del Valle Martinez, Idamis; Harris, Miriam; Zimmerman. (Powerpoint) Great Lakes Climate II. Impact of Decreasing Water Levels on Great Lakes Wetlands. NASA.

Owen, Nathan. "NASA DEVELOP Explores Georgian Bay Using NASA Earth Observations".GBF's Winter 2015 Newsletter, Vol 6, Issue 1.Retrieved December 28, 2015 from

Ronca, Debra. "How Wetlands Work". Retrieved December 28, 2015 from

Sweetnam, David. "NASA to investigate Georgian Bay Water Levels". GBF's Autumn 2014 Newsletter, Vol 5, Issue 3. Retrieved December 28, 2015 from

"Groundwater Basics". Retrieved December 28, 2015 from . Retrieved December 28, 2015 from

Great Lakes Climate - NASA DEVELOP Fall 2014 @ Langley Research Center. NASA DEVELOP National Program youtube.

Great Lakes Climate II - 2015 Spring NASA DEVELOP @ Langley Research Center. NASA DEVELOP National Program youtube.