Author: Brian R. Haines
The work of hazard mitigation is designed so that today’s investment will pay off in the event of a future threat; it’s playing the long game. While the damages done in Western North Carolina by the remnants of Tropical Storm Fred are undeniable, even greater losses would have occurred without the hazard mitigation measures put in place after Hurricane Frances and Tropical Storm Ivan more than a decade ago.
In the wake of those storms, 22 structures near Canton were acquired in 2006 through the Hazard Mitigation Grant Program for just over $938,000. Those structures were torn down and the land returned to a natural state where the waters of the Pigeon River could flow freely when water levels are high. The cost to acquire those structures by 2020 standards would be more than $1.2 million. It’s estimated that the damages avoided during Tropical Storm Fred where those acquisitions were made is $1.19 million, resulting in recouping nearly 100% of the investment.
“Assuming that the damages incurred due to Tropical Storm Fred in August 2021 would have been similar to those incurred in 2004-06, the period in which the acquisition project was developed and implemented to remove these structures from the flood plain, we estimate the benefit cost ration is nearly one to one,” said Chris Crew, mitigation plans manager with NCEM. “With the expected life of this project, or the amortization period, being 100 years, we have 85 years during which to accrue the rest of the benefit.”
Using GIS data, N.C. Emergency Management Hazard Mitigation staff ascertained that the flood depths after Frances and Ivan showed flood depths of 54 to 120 inches in the same floodplain. According to records provided by the N.C. Climate Office, Hurricane Frances delivered approximately 5.4 inches of rain to the area between Sept. 6 and 8, 2004, and Tropical Storm Ivan 5.4 inches from Sept. 16 - 17, 2004. Likewise, Tropical storm Fred delivered approximately 6.9 inches of rain to the area between Aug. 15 - 17, 2021.
Crew adds that this estimate does not include losses such as the content of the structures, displacement or other economic or intangible losses that may have occurred. It’s also important to note that the rainfall amount recorded for Tropical Storm Fred was at least 1-inch greater than either Frances or Ivan, which means the benefit of the mitigation actions is likely somewhat higher.
Since 1998, the Hazard Mitigation Section of NCEM has administered more than $1 billion in mitigation funding. In 2018, the Pew Charitable Trust reported on a National Institute of Building Sciences study finding that every dollar invested in natural hazard mitigation returns six dollars in avoided future losses. When adjusted for riverine flooding (the principal hazard in North Carolina) that figure jumps to a 7:1 benefit/cost ratio.