Alberta Government Study Update Notice
Mar 16, 2018 Bow and Elbow River Hazard Study Update
© 2018 Government of Alberta
Bow and Elbow River Hazard Study Update
We would like to provide an update on the status of the Bow and Elbow River Hazard Study.
Substantial progress has been made since the multi-year study started in fall 2015. All components of
work are either complete or in late stages. Although the study was expected to be complete in
December 2017, project timelines were extended to include additional analysis and an expanded set of
deliverables. Technical work is now expected to continue through spring 2018.
We recognize there will be tremendous interest in any new flood mapping. Our study finalization
process includes municipal and First Nation review and public engagement for major components, as
appropriate. Our goal is to provide useful tools to communities and the public as soon as possible.
The Bow and Elbow River Hazard Study is being completed under the provincial Flood Hazard
Identification Program, the goals of which include enhancement of public safety and reduction of future
flood damages through the identification of river and flood hazards.
More information about the Alberta Flood Hazard Identification Program can be found at:
If you have any questions regarding this work, the project engagement specialist, Ruth DeSantis, can
be contacted at:
• Telephone: 403 355-2493
Project Background and Study Progress
The Bow and Elbow River Hazard Study will identify and assess river-related hazards along 80 km of
the Bow River and 70 km of the Elbow River, including lengths of Bragg and Lott Creeks. The study
area covers the Bow River between Bearspaw Dam and the Highwood River confluence, and the
Elbow River between Bragg Creek and the Bow River confluence. The study project reach includes
Calgary, Bragg Creek, Municipal District of Foothills, Redwood Meadows, Rocky View County, and
The main study deliverables outlined below include a hydrology assessment, new hydraulic river
models, updated and new flood inundation and flood hazard mapping, a flood risk inventory, and a
channel stability assessment – all of which will be provided to each community within the study reach to
support their local emergency response and land-use planning needs.
• Survey & Base Data Collection – Complete
Hydraulic models and flood maps require high-accuracy base data. Field surveys and LiDAR
remote sensing are used to collect river and floodplain elevations, channel cross section data,
bridge and culvert information, and dedicated flood control structure details.
• Hydrology Assessment – Complete
The hydrology assessment estimates flows for a wide range of possible floods along the Bow
and Elbow Rivers, including the 2, 5, 10, 20, 35, 50, 75, 100, 200, 350, 500, 750 and 1000-year
floods. The analysis will include the 2013 flood.
• Hydraulic River Modelling – Late Stages
A new hydraulic computer model of the entire river system will be created using new survey
data and modern tools. The model will be calibrated using surveyed highwater marks from past
floods to ensure that results for different floods are reasonable.
• Flood Inundation Mapping – Late Stages
Flood maps for thirteen different sized floods, based on the hydraulic model results and the
hydrology assessment, will be produced. Flood inundation maps can be used for emergency
response planning and to inform local infrastructure design. These maps show areas of isolated
flooding or areas that could be flooded if local berms fail.
• Flood Hazard Mapping – Late Stages
Flood hazard mapping divides the 100-year floodplain into floodway and flood fringe zones,
which show where flooding is deepest and most destructive. These maps can be used to help
guide long-term development planning.
• Flood Risk Assessment & Inventory – Late Stages
An inventory of structures at risk of flooding for all of the mapped flood scenarios will be created.
This flood risk assessment and inventory can support future flood damage assessments.
• Channel Stability Investigation – Late Stages
The main goal of this study component is to provide insight into general channel stability along
the Bow and Elbow Rivers. We will compare current and historic riverbank locations and
channel cross sections as far back as 1949 using historic aerial photos.