South Carolina floods a wake-up call for the future

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While Hurricane Joaquin didn't make landfall in the United States, it contributed to the massive flooding that South Carolina is now enduring. The toll in terms of loss of life and damages continues to climb. It will be some time before the flood waters recede and attention shifts to rebuilding, but rebuilding shouldn't just be about putting things back the way they were. The aftermath of an event like this provides an opportunity to think about what to rebuild, where to rebuild, and how to rebuild so we don't just duplicate the same vulnerabilities.

An important aspect of that rebuilding effort should be to update the state's hazard mitigation plan, essentially the state's assessment of its vulnerability to future natural disasters and the actions it could take to be better prepared. My colleagues, Ben Chou and Joel Scata, have also written on the importance of updating flood risk standards and developing water infrastructure with future flood risks in mind.

The aftermath of the flooding in North Charleston, South Carolina caused by over 15 inches of rainfall resulting from Hurricane Joaquin. Photo by Ryan Johnson and used under Creative Commons license.

In 2013 South Carolina updated its Hazard Mitigation Plan. One glaring shortcoming of the plan is that it gives almost no analysis of how climate change might make natural disasters more frequent or severe. It does mention that the IPCC projects sea levels to rise up to 2 meters, but that's the extent of the state's assessment of climate change.

By and large, the state makes the same mistake that most states make in developing these plans. They rely almost exclusively on past history to determine the kinds of storms and natural disasters they should be prepared for. That approach is fine and dandy as long as the future looks exactly like the past. But climate change makes that a false assumption.

A full accounting of the damages will take weeks to compile, but early estimates from Aon Benfield, a prominent reinsurance company, suggest total economic losses could "easily exceed" $1 billion. But we don't have to wait for a full accounting to decide that it's time to make ourselves better prepared for storms like these in the future.

We've heard many times this week how these floods are the result of a one thousand year storm (a storm with a 0.1% chance of occurring in any given year). But the so-called "one thousand" or "one hundred" year storm of the past is likely to happen more frequently in the future. Flooding from Superstorm Sandy was considered a 500-year flood event, but scientists think similar levels of flooding could occur every two to twenty years due to climate impacts. Climate change slowly tilts the odds in favor of these kinds of extreme events.

And the last time South Carolina experienced damages on this scale was not one thousand years ago. It was 26 years ago, when Hurricane Hugo made landfall in September 1989. Hugo was a Category 4 hurricane that made a direct hit on the state's coastline, causing more than $10 billion in damages in South Carolina, Puerto Rico, and other parts of the Caribbean.

South Carolina would be wise to re-examine its hazard mitigation plan and account for the increasing likelihood of extreme events.

Eleven counties in South Carolina have been declared a federal disaster area due to the flooding. On the Black River, the previous record for floods was shattered as floodwaters rose 2.5 feet higher than ever before. Flood records were also set on the Congaree River and Black Creek. And waters will continue rising in some parts of the coast as floodwaters move downstream. Major flooding is expected on the Santee River, which isn't expected to crest for another four days.

As many as 15 people have lost their lives to flooding in South Carolina. In and around Columbia, many are without water or under a boil order due to water main breaks and a boil order that affects 375,000 people. Undoubtedly, other communities throughout the state face a similar situation. Another tragic result of these floods is the breaching of multiple dams around the state, six of which are in Richland County alone. South Carolina has 2,380 dams that it's responsible for inspecting, but the state's dam safety program is now coming under scrutiny in the wake of so many failures.

Updating South Carolina's hazard mitigation plan would not magically protect the state from these kinds of damages. But by examining future climate impacts, the state could anticipate events that may fall outside its historical experience.

These plans are essentially a blueprint for anticipating future disasters and determining what the options are for preparing for them. A state's hazard mitigation plan can be a resource for other state and local governments to help determine their vulnerabilities. That knowledge should be used to guide decisions on what to build, where to build, and how to build. But you can't trust your blueprint for the future if it fails to recognize what the future will look like. And climate change has, undeniably, altered the future of disasters.