Hydrological Habitats
Hydrological features across Alberta change continually and require regular mapping. The Geospatial Centre’s Earth Observation Insights Unit uses regular, repeating satellite image streams alongside other geospatial data, such as terrain, to capture aspects of the province’s dynamic hydrological habitats. Combining province-wide imagery from multiple years and seasons enables us to map changing surface water extents, while including terrain can help us pinpoint depressions and areas likely to flood.
We have two key areas of work on hydrological habitats:
- Algal bloom monitoring
- Hydro-temporal variability
Each focuses on changes to surface water features and relies on geospatial inputs from multiple dates, as well as cloud computing and machine learning technology.
The effective and timely monitoring of harmful algal blooms in Alberta lakes is important for managing freshwater quality, aquatic ecosystem health, and potential risks to human and wildlife health.
We are collaborating with the University of Alberta, the Alberta Lake Management Society, Alberta Environment and Protected Areas, and several other organizations to develop methods for the near-real time mapping of algal blooms. Work has focused on the satellite remote sensing of cyanobacteria pigments in particular lakes, identifying the right combination of wavelength reflectances in optical satellite imagery, and linking these to surface water samples. Imagery from both Sentinel-2 and Sentinel-3 are being explored. The former offers higher spatial detail with less frequency, while the latter offers frequent images at a coarser scale.
This collaboration is ongoing; a detailed description of a previous project on Pigeon Lake in central Alberta can be found under Projects and Collaborations.
Cyanobacteria algal bloom in Pigeon Lake, summer 2020 (photo: Alberta Lake Management Society).
Surface water is dynamic and its extent can vary daily, seasonally, and annually. Monitoring changes in extent is important for effective water resource management.
Previous work in the Geospatial Centre took advantage of the new radar data available through the European Space Agency’s Sentinel-1 satellites. Images covering the growing season for several years were compiled to extract summaries of surface water variability over time. The result is our hydro-temporal variability layer containing the percentage of time that a particular location (e.g., a 10-m pixel) is classified as “water” in the images from that time period. This ranges from 0% for areas with no open water to 100% for permanent water bodies. The data offer an estimate of water permanence and variations in extent over the represented time period.
The hydro-temporal variability dataset can be accessed in our Open Data Portal. Read more details about this product and how it was created in the accompanying technical documentation and in this publication.
