Data Limitations

Throughout the Environmental Sensitivities Project, a number of observations were made about sensitivity, restoration opportunities and Edmonton’s ecological network. Those learnings must be framed in context of the limitations of this study.
Specifically, the following limitations apply:
  • Sensitivity analysis was GIS-based and relied on existing digital data where available. Additional data was created through GIS analysis and digitizing of existing reports to address known data gaps (e.g., non-native vegetation mapping at the neighbourhood level, stream and wetland mapping, unique landforms), but ground-truthing was not part of the scope of this study. The resulting mapping is best considered a landscape level assessment. Important notes to be aware of:
    • If this information is used in site-specific studies, surveys should be conducted to confirm local sensitivities and identify assets that could not be included in this landscape level analysis due to a lack of data.
    • Wetlands less than 0.5 ha were remotely sensed using a combination of depression analysis (2012 LiDAR (1 m) data) and wetland vegetation classification (using the Normalized Difference Vegetation Index (NDVI) measurement of spectral reluctance values captured in 2013 four band orthoimagery). Therefore, all wetlands should be considered desktop derived and any site analysis should confirm wetland status.
  • Strict criteria were imposed on the selection of digital datasets incorporated into the model to ensure the comprehensive analysis of the entire City at a comparable scale of resolution. Accordingly, some assets with known environmental sensitivity could not be included in the assessment due to a lack of available digital datasets, lack of City-wide coverage, or coarse resolution.
    • Known data gaps include groundwater recharge/discharge areas, and specific archaeological, historical and paleontological sites on the Tablelands.
    • Other datasets are suspected to be incomplete, but met other criteria and thus were included. For example, unique landforms included only large features mapped in previous studies (e.g., Devon sand dunes, Beaver Hills moraine). Smaller local features such as groundwater springs and bentonite bluffs are known to exist, but have not been mapped digitally.
    • Rare plant and wildlife observations obtained from Provincial datasets do not represent comprehensive inventories, and may not include locally known occurrences.
  • Environmental sensitivity analysis incorporated recent mapping of the ecological network of native and non-native vegetation, streams, wetlands and other waterbodies as much as possible, with practical limitations. The City’s urban Primary Land and Vegetation Inventory (uPLVI) and remote sensing data used for this assessment were completed in 2015 and 2013 respectively, which is relatively recent, but not current. Similarly, infrastructure data (roads, subdivision development and stormwater facilities) provided varied in month of acquisition in 2015. Some discrepancy between mapped and actual features may result, due to loss and changes from ongoing development activities.

Despite these limitations, the environmental sensitivity (ES) classification approach provides a solution to the key challenge of ecological network planning in Edmonton - that of putting the river valley and Tablelands sites on the same scale of environmental sensitivity in a way that can best inform management. The ES data provides important baseline information of an area’s assets, threats and constraints which should be further explored and confirmed through site survey when site-specific initiatives are being evaluated. 

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