RMS’ Jeff Waters enforces the importance of the use of modeling tools and datasets to help the market quantify the risks of major hurricane events.

Jeff Waters, senior product manager, RMS

“Hurricane Pam” was a hurricane that never happened. In response to Hurricane Georges in 1998, Pam was a FEMA-led exercise based on a fictional category three strength hurricane hitting New Orleans. It saw a range of federal, state and local agencies involved in planning for an event that could threaten 60,000 lives, trapping hundreds of thousands more and dramatically impacting utilities and resources. The exercise saw draft plans formed in early 2005 — but was never finished.

Just a few months later, Katrina made landfall in Louisiana on Monday, 29 August 2005 as a large category 3 event. New Orleans and surrounding areas suffered maximum sustained winds of 125 miles per hour (200 km/h), rainfall in excess of 8-10 inches (20-25 centimeters), and storm surge up to 25 feet at Lake Borgne. Eighty percent of the city was flooded. The impact is well documented. Katrina fell heavily on impoverished communities, FEMA’s response was heavily criticized, and more than 1,000 people died.

Fifteen years on, New Orleans has seen $20bn of federal, state and local government investment on over 350 miles (560 kilometers) of levees, flood walls, gates and pumps. The US Army Corps of Engineers have turned New Orleans into a “fortress city” with a Hurricane and Storm Damage Risk Reduction System based on protection against a 100-year return period event, though it is closer to protection for a 500-year event.

If Katrina struck again…

What would be different if Hurricane Katrina struck again? New Orleans has never been naïve to its situation—since its formation, the city has struggled with the water, sitting in a “bowl” which is mainly below sea-level. Sea levels are rising, the city is sinking and many scientific theories suggest tropical cyclones could become more intense as the climate changes.

But at the same time, resilience has grown to match these growing risks. New Orleans and the wider region is seen as a poster child for changing how coastal cities and states think about risk and resilience following natural disasters like Katrina.

“New Orleans is seen as a poster child for changing how coastal cities and states think about risk and resilience”

The risk is changing—climate change attribution has pointed to wetter hurricane events, published studies suggest that climate change likely boosted Hurricane Harvey’s rainfall by 20 to 40 percent. Much has changed from a cat modeling perspective as well. Since 2005, probabilistic hurricane models, such as the RMS North Atlantic Hurricane Models, have undergone significant improvements, incorporating new data, science, and methodologies to help (re)insurers and other users quantify the frequency, severity, and sensitivities of the evolving hurricane risk landscape, including those associated with the New Orleans levee systems in 2005 and today.

We’ve also seen the emergence of probabilistic flood models to help the market assess various types of inland flood risk at granular levels. The RMS US Inland Flood HD Model, for instance, considers the complex hydrodynamics of pluvial and fluvial flooding within and across regions, as well as individual building vulnerability, taking into consideration the presence (or absence) and failure likelihood of many types of natural and manmade flood defense systems.

Hurricane Katrina sparked necessary improvements in New Orleans, so it can withstand the next major event. Today, there are many modeling tools and datasets available to help the market quantify the risks of major hurricane events both near and long-term, and the cost-benefit of mitigation efforts, all of which can inform proper preparation and resiliency. Getting solid plans in place is vital, and unlike the hypothetical Hurricane Pam, those plans need to be in place now or put into action soon, before the next Katrina strikes.