Flood resilience program - studies and reports

The City completed the Calgary River Valleys Groundwater Study to better understand river-driven groundwater flood risk in river valley communities. The study included: 

• Modelling groundwater levels during flood events in river valley areas.
• Estimating potential impacts to buildings and properties. 
• Reviewing options to improve resilience. 
• Creating a new river flood induced groundwater risk map and “groundwater flood fringe” area for Calgary. 

The study found that during major floods, such as a 1:100 flood event, groundwater levels can rise and affect areas beyond the current flood hazard area. It also found that many Calgary buildings, particularly older homes in established communities, are vulnerable to river-related groundwater flooding. 

The Groundwater Flood Fringe identifies areas where a 1:100 river flood could raise groundwater to within three metres of the surface. This depth was used because groundwater at this level is more likely to affect a typical residential basement, which is usually about 2.4 to 2.7 metres, or 7 to 8 feet, deep. 

The study and maps provide insights to inform decisions on land-use planning, building practices, and emergency management, ultimately strengthening Calgary’s river flood resilience.

Prepared by: Associated Engineering (2018)

The City of Calgary requested a study into whether flood barriers may be an effective solution to reduce flood risk in our city. The Study used a Triple Bottom Line (TBL) approach to evaluate the social, environmental and economic costs and benefits, using a specific process built for this study.

The costs and benefits assessed barrier protection at various heights for many communities. Information from this study was included in our city-wide Flood Mitigation Measures Assessment.

Please note: Associated Engineering created conceptual designs for community-level flood barriers to help calculate rough costs and benefits, and to see if barriers in these general locations were technically feasible.

It’s important to note that height, location on individual properties, and/or aesthetics of the concepts are not indicators or a foundation of the proposed community flood barriers.

Prepared by: IBI Group and Golder Associates (2017)

After the 2013 flood, the Flood Expert Management Panel recommended a study to explore the impacts and benefits of mitigation measures beyond barriers to reduce flood risk in Calgary. This study looked at potential flood damages under different scenarios with different mitigation options in place. These options were combinations of reservoirs, flood barriers, stormwater improvements and emergency response measures.

The study compared the cost, benefits and social-environmental sustainability of each mitigation scenario. They were evaluated on social well-being, environmental protection, economic well-being and ease of implementation. The assessment criteria for each scenario was based on technical studies and expertise, international best practices and public engagement.

The recommended flood mitigation scenario included:

• upstream reservoirs on the Bow and the Elbow,
• small barriers at specific locations along the Bow, and
• policy changes.

This combination of measures provided the greatest flood protection, was the most environmentally sustainable and provided the timeliest and equitable protection to flood-prone communities.

Please note: : Rough costs were compared to benefits for each mitigation scenario. As each individual project design progresses, the cost-benefit of each project will be refined and reassessed. This will be done on an individual project level and within the context of how it contributes to flood resiliency for the city as a whole.

The cost-benefit is assessed using a triple-bottom-line approach that considers not only financial costs, but also social and environmental impacts and benefits.

• Flood Mitigation Options Assessment Summary
• Calgary Flood Mitigation Options Assessment Report - Full study

Prepared by: Klohn Crippen Berger (2017)

This study explains how the Bow River, Elbow River, Fish Creek, Nose Creek and West Nose Creek were affected by the 2013 flood, how they have recovered since the flood, and how they are likely to evolve in the future.

• Calgary Rivers Morphology - Table of Contents
• Calgary Rivers Morphology - Summary Report
• Calgary Rivers Morphology - Main Report

This report summarizes the status of various flood mitigation projects and provincial upstream mitigation in 2022.

This report is the recommended flood mitigation approach for Calgary. It is based on the technical studies listed below, expert advice and public engagement. Council directed The City to execute the strategy outlined in the report. We continue to engage and work with communities as we explore and design flood mitigation projects in their neighbourhoods.