This site presents a comparison of flood maps produced in the City commissioned report titled “Hydrogeological Characterization and Groundwater Flow Modelling Report” by Klohn Crippen Berger(KCB) dated Jan 4, 2021, and flood maps produced by the City in their Bowness flood barrier: Feasibility Study - Community Information Booklet, both copyright the City of Calgary 2021.

The first map below is from the KCB report, and has had property lines added to it for easier navigation. This map shows the extent of groundwater flooding for a flood which reaches the designed flow rate of the barrier (1200 m3/s or 1:20 year flood level), with the barrier in place.

  • Red colour is the worst with the water rising through the ground to surface and becoming overland flooding.
  • Dark Blue is the deepest representing 6.5 to 8 feet. 6.5 ft would be a typical basement depth.
  • All other colours - water will rise between 6.5ft and surface. Basements are highly likely to be flooded.

According to the City's groundwater video, basement floors are not impermeable and will flood once the water table rises above the basement floor elevation, if there is no other mitigation.

The KCB Report may be read in full by visiting the City of Calgary website here: https://www.calgary.ca/uep/water/construction-projects/construction-projects-and-upgrades/community-flood-barrier-related-studies-and-reports.html

Instructions:
Use the zoom buttons +- at the bottom of the image to zoom in.
Click and drag to move image. 

This flood information is from the City commissioned Klohn Crippen Berger report (Jan 2021).


The map below is from page 9 of the City’s community information booklet.

 

As you can see, these maps are very different indicators of groundwater. The first shows red (which is groundwater to surface) for most of Bowness east on Bow Crescent. The city booklet map above only shows a few (5-6) pockets. As well the city booklet does not show anywhere on the map, the light blue, yellow, or orange colours, which represents water levels above the typical basement floor.

In the City’s information sessions on Jan 13 and Jan 19 2021, the question was asked as to what the City map in the booklet represented. KCB answered that it represented a moment in time earlier in the flood. Also asked was why the City did not publish a map showing the water levels relative to people’s basements. The City responded with the “focus” of the barrier is overland flooding.

For more information go to bownessrfm.ca

 

 

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