Filling in the flood gaps

RMS is hoping to fill in the gaps left by what re/insurers consider to be a dearth of flood claims data from the Federal Emergency Management Agency (FEMA) with its newest flood model. According to Pete Dailey, vice president of model product management at RMS, the modelling firm is looking to release its flood model later this year which will cover the entirety of the contiguous United States. In contrast, FEMA’s flood maps only cover parts of the US. “The 100 year FEMA flood zone is just a delineation of whether you’re inside or outside. It’s not saying that at a 100-year return period this is the inundation depth that you can expect. It’s just saying you're inside or outside. Because it’s a line, you literally can walk outside of the neighborhood, and be inside here, and outside there, but we all know the risk doesn’t change that rapidly,” said Dailey. Mapping as large a landmass as the US is no easy task, but one that Dailey said RMS has taken to heart. As Dailey explained, one of the requests he and his team regularly receive from clients is that any flood model from the firm must be comprehensive. “This model is five times the size of the European flood model, which at the time it was developed was the largest single investment that RMS had ever made in a model. There was roughly 50 man years packed into a six year development cycle,” Dailey said, highlighting the scope of such an undertaking. “Most of the model vendors have modeled storm surge and coastal flooding for roughly 20-plus years, because it’s related directly to the hurricane modeling work. That’s been covered, but what’s been missing is the inland flood piece. Some models cover a portion of the gap, but they mainly focus on riverine flooding. What many of them may not cover is surface or urban flooding, when heavy rainwater floods an area beyond a drainage system’s capabilities to absorb it, which can cause just as much damage as riverine flooding.” Flooding in Houston following Hurricane Harvey was an example of this type of inundation. “You also have to cover inland flooding from tropical and non-tropical storms in order to be comprehensive. At least two of the five major vendors, if not more, are completely missing the tropical cyclone component of the inland flooding risk, they simply do not model that. "Harvey was a great example of a tropical storm where the predominant loss driver was inland flooding, and some models would be missing that component completely,” Dailey said. Another component that RMS had to take into account was the presence of flood defences, namely levies in different areas. According to Holy Widen, product manager for the Americas climate models at RMS, only 15% to 20% of levies are documented in the US. “Data from sources regarding levies only covers 15% or so of the river network. We’re missing roughly 85% in terms of levy presence. To get a standard of protection or the level at which you known a defence would protect against an event is even smaller, maybe just a handful of percent. So we actually have a model within our model that looks at defences and the probability of the presence of a levy and the level of protection it provides,” she said. According to both Dailey and Widen, many levies in local jurisdictions were simply never documented, while natural levies also exist that provide flood protection, and in turn can be modeled as well.

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