| Title | Wetlands status and trends in Canada: development of a baseline |
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| Author | Brisco, B; Saleh, B; Grenier, M; Pratt, A; Boychuck, L; Merchant, M; Mahdianpari, M; Mohammadimanesh, F |
| Source | Program, 41st Canadian Symposium on Remote Sensing/Programme, 41e Symposium canadien de télédétection; 2020 p. 33-34  Open Access |
| Links | Online - En ligne (complete
volume - volume complet, PDF, 17.5 MB)
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| Image |  |
| Year | 2020 |
| Alt Series | Natural Resources Canada, Contribution Series 20200545 |
| Publisher | Canadian Remote Sensing Society |
| Meeting | 41st Canadian Symposium on Remote Sensing; July 13-16, 2020 |
| Document | book |
| Lang. | English |
| Media | on-line; digital |
| File format | pdf |
| Province | Canada; British Columbia; Alberta; Saskatchewan; Manitoba; Ontario; Quebec; New Brunswick; Nova Scotia; Prince Edward Island; Newfoundland and Labrador; Northwest Territories; Yukon; Nunavut |
| NTS | 1; 2; 3; 10; 11; 12; 13; 14; 15; 16; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 52; 53; 54; 55; 56; 57; 58; 59; 62; 63; 64; 65;
66; 67; 68; 69; 72; 73; 74; 75; 76; 77; 78; 79; 82; 83; 84; 85; 86; 87; 88; 89; 92; 93; 94; 95; 96; 97; 98; 99; 102; 103; 104; 105; 106; 107; 114O; 114P; 115; 116; 117; 120; 340; 560 |
| Lat/Long WENS | -141.0000 -50.0000 90.0000 41.7500 |
| Subjects | hydrogeology; surficial geology/geomorphology; geophysics; Nature and Environment; Science and Technology; wetlands; surface waters; organic deposits; ecosystems; environmental studies; remote sensing;
satellite imagery; mapping techniques; Canadian Wetland Classification System; Sentinel-1; Sentinel-2; Trends; environmental baseline studies; Classification; Geographic data; synthetic aperture radar surveys (SAR); Maps |
| Illustrations | sketch maps |
| Program | Canada Centre for Remote Sensing Flood Mapping Guidelines |
| Released | 2020 07 10 |
| Abstract | Wetlands are important ecosystems delivering goods and services to a number of important functions including providing key habitat to many plants and animals, maintaining water quality and quantity such
as controlling floods, offering food and recreational opportunities for humans and acting as a carbon sink. They are also key components of both the water and carbon cycles. Thus, baseline information on the large-scale spatial distribution of
wetlands is critical for monitoring these productive ecosystems, obtaining information on their historic status and trends, and acquiring accurate inputs for carbon budget, habitat, biodiversity, and resource management strategies. Production of
nationally synoptic baseline information is of particular concern in countries such as Canada, which contains a quarter of the world's wetlands. Traditionally wetland classification is a time-consuming and expensive activity involving airborne
photography and field visits to conduct wetland surveys. These considerable expense and time requirements means these type of classification efforts can only done periodically. The state of the art of satellite remote sensing for wetland
classification has been developing for the last couple of decades and has now reached the point of cost-effectively producing accurate wetland classifications at a reasonably high scale on a global basis.
The Canadian Wetland Classification System
has five classes: shallow water, marsh, bog, fen, and swamp. We produced a high-resolution 10-m wetland inventory map of Canada using these five classes, covering an approximate area of one billion hectares, using 2016-2018, multi-source (Sentinel-1
and Sentinel2) EO data and a large volume of reference samples within an object-based random forest classification scheme on the Google Earth Engine cloud-computing platform. Sentinel-1 GRD data in GEE already subjected to several preprocessing
steps. These include thermal noise removal, radiometric calibration, and terrain correction, resulting in the production of geo-coded SAR backscattering coefficient images in dB. An adaptive 7x7 sigma Lee filter was then employed to suppress the
effect of speckle noise and further speckle noise reduction was accomplished by producing the multi-year seasonal median composite. Both Sentinel-2A and Sentinel-2B Level-1C reflectance data used in this study. A total of 211,926 Sentinel-2 images
from the summers of 2016, 2017, and 2018 were queried from the GEE data pool. However, some of these observations contaminated with cloud coverage and were not useful. Accordingly, a selection criterion applied to remove observations with cloud
percentage greater than 20% then the 'QA60' bitmask band (a quality flag band) available in the metadata used to detect and mask out remaining clouds and cirrus. The reference sample sources came from a number of federal, provincial, and NGO sources.
The accuracies exceeded 80 % in most regions with an overall accuracy of 78.88 %. This consistent, similar timeframe, national coverage large scale maps can be produced annually or even seasonally, resources permitting.
The resulting nationwide
wetland inventory map illustrates that 19% of Canada's land area is covered by wetlands, most of which are peatlands dominate in the northern eco-zones. This represents a general increase of wetland extents in Canada (~6%) relative to past studies
potentially reflecting recent climate change. Importantly, the resulting ever-demanding wetland inventory map of Canada provides unprecedented details on the extent, status, and spatial distribution of wetlands, thus, is useful for many stakeholders,
including federal and provincial governments, municipalities, NGOs, and environmental consultants. |
| GEOSCAN ID | 327816 |
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