The Berm Won’t Work

11 Reasons the Proposed Berm WILL NOT Protect Bowness Residents from Flood Damages

Conclusions

In 2021, The City completed hydrogeological (groundwater), geophysical and geochemical investigations in the Bowness community to obtain data on alluvial sediment thicknesses, compositions and distribution, as well as groundwater flow directions and sources.  BRFM commends the City for completing the studies. The study results are critical before a decision is made as to whether or not a barrier would be effective in protecting residents from future flood damage losses, be they physical or financial. The results of all of these studies have now been presented to the Bowness Community Flood Mitigation Working Group, with the possible exception of the final Stormwater study which is being conducted by The City itself and due to be completed early in 2021.

After reviewing the long-awaited studies conducted by The City and in consultation with 3rd party experts, BRFM maintains its original position that with the proposed surface event barrier Bowness residents who live adjacent to the river or nearby will experience costly flood damages from groundwater.

It is apparent from the tone and content of the Community Information Booklet that were delivered in January 2021, that The City is reluctant to admit that they are only concerned with overland flooding, while recognizing that widespread groundwater flooding will occur in the neighbourhood with the barrier in place. It appears, The City is not considering in the barrier decision, the extensive damage and financial losses that will be incurred by Bowness residents.

Lastly, upstream flood mitigation, designed to limit flow through Bowness to less than 800 m3/s, should be the sole focus of The City’s efforts at this time through cooperation with the GoA. Their focus should  not be a technically flawed surface event flood barrier that  will be environmentally destructive, cost an estimated $35 million and a demonstrably ineffective waste of taxpayers’ dollars. The imperative continuation of the TransAlta Operating Agreement by The GoA affords the Bowness community significant protection from both groundwater and overland flooding for up to about a 1:30 year flood event. Other communities are being offered effective protection from both overland and groundwater flood damages up to at least a 1:100 year event, and the residents of Bowness should be provided the same consideration through the construction of sufficient upstream mitigation to achieve this.

References Cited

Abboud JM, Ryan MC, Osborn GD. (2018) Groundwater flooding in a river connected alluvial aquifer. J Flood Risk Management.
2018; 11:e12334. https://doi.org/10.1111/jfr3.12334

AMEC Earth & Environmental (2007), Calgary, City of Lethbridge Flood Risk Mapping Study Report

Associated Engineering (2018), Permanent Flood Barrier Protection Assessment, report for the City of Calgary p:\20133936\00_flood_protect_cd\engineering\03.02_conceptual_feasibility_master_plan_report\20161012_finalreport\final\rpt_cgy_river_flood_final_2018-04-26.docx

Cantafio, L. (2012), Groundwater-surface water interaction, non-point source chloride loading, and flow generation along an urban river, M.S. thesis, 164pp., Univ. of Cal. at Calgary, Alberta. September.

City of Calgary. (2016). Flood Mitigation Measures Assessment. Calgary: City of Calgary.

City of Calgary. (2021). Bowness Flood Barrier: Feasibility Study, Community Information Booklet (distributed in January, 2021).

Government of Canada, Environment and Natural Resources; https://wateroffice.ec.gc.ca/search/historical_e.html

Hugo, K. (2015). Bow river floods and groundwater. Water Technologies Symposium, Alberta, Canada: Kananaskis.

IBI Group/Golder Associates Report (2017). Flood Mitigation Options Assessment-Phase 1. Prepared for the City of Calgary

Klohn Crippen Berger (January, 2021). CoC Bowness Flood Control Barriers, Hydrogeological Characterization and Groundwater Flow Modelling Report, prepared for The City of Calgary

Klohn Crippen Berger, 2021, Hydrogeological Characterization and Groundwater Flow Modelling, 201103DR Bowness Numerical Model, APPENDIX V, Numerical Groundwater Model – Groundwater Flood Mitigation Simulations

Ryan, Cathy (2014). The Role of Groundwater in Flooding. Canadian Water Resources Association’s (Alberta Chapter) conference on the 2013 Alberta Floods, The Rains, Response, Recovery & Resiliency, March 23-25, 2014 in Calgary, Alberta. https://www.youtube.com/watch?v=I3I5PolKGlg