Retrospective Benefit-Cost Analysis of BC Disasters: Technical Report

Porter, Keith Alan

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Retrospective Benefit-Cost Analysis of BC Disasters: Technical Report Público Deposited

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Citeable URL: https://scholar.colorado.edu/concern/reports/tq57ns632

Abstract

This study asks how much loss and suffering can be avoided by prudent mitigation using
accepted procedures most strongly recommended by authorities such as the Institute for
Catastrophic Loss Reduction, National Research Council of Canada, and U.S. Federal Emergency
Management Agency. These measures have been shown to have a high benefit-cost ratio and
effectively reduce damage in severe storms, wildfires, and earthquakes. It estimates what it
would have cost to comply with these measures before three large, historic storms and fires in
British Columbia and before four large, hypothetical – but inevitable – future earthquakes,
as shown in Table ES-1. It reaches three major findings:

1. We can reduce flood and storm losses through pluvial and fluvial flood mitigation measures
and by improving connections between building elements to resist strong winds. Undertaking
these measures to improve 12,400 buildings prior to the 2021 November Rainstorm would
have cost $1 billion but avoided $2.3 billion in losses, for a retrospective benefit-cost ratio of 2:1.

2. We can reduce wildfire losses through vegetation management, use of noncombustible
building materials, and undertaking community protection measures. For 100 Lytton
buildings to comply with the National Guide for Wildland-Urban Interface Fires would have
cost $2 million to avoid $300 million in losses, for a retrospective benefit-cost ratio of 170:1.
For 6,400 buildings affected by the 2017 Wildfires to similarly comply would have cost
$110 million but avoided $340 million in losses, for a retrospective benefit-cost ratio of only 3:1.

3. We can reduce losses in inevitable future earthquakes by strengthening weak foundations in
older woodframe buildings, strengthening the soft-story parking level of older woodframe
apartment buildings, and adding engineered tie-downs to manufactured homes. Mitigation
prior to four hypothetical earthquakes would require retrofitting 50,000 to 80,000 buildings
at a total cost of $1 billion to $4 billion, avoiding up to twice the retrofit cost in losses.
Retrospective benefit-cost ratios are approximately 2:1.

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