Extent of Canada's wetlands indicator: data sources and methods, chapter 5


5. Caveats and limitations

Wetlands are difficult to map in part because different types of wetlands contain different vegetation, and because they vary seasonally. The lack of a consistent vegetation pattern can lead to errors when using automated or semi-automated methods designed for remotely sensed data such as aerial photographs or satellite imagery, and intensive ground campaigns are required to produce maps with low error rates. The indicator uses the highest quality datasets that are available, but accuracy varies regionally. The greatest uncertainty is in northern areas. Datasets with lower accuracy tend to underestimate wetland extent, so national estimates are likely conservative.

Wetland data accuracy for national wetland layer (circa 2000), Canada, 2016

Map
Long description

The map shows the expected accuracy of data contained in the wetland extent map. Areas shown in the lighter color (yellow) are based on CanVec data and have an expected accuracy of up to 70%. Areas shown in darker colors use additional datasets and have at least 70% accuracy.

Note: Values are estimated wetland classification accuracy of different contributing datasets. Darker colours are more accurate.
Source: Canadian Wildlife Service, 2016.

More than half of the wetland polygons (58%) are partially classified, meaning that they were identified as wetlands, but could not be clearly defined as bog, fen, marsh, swamp, or shallow water.

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