Flood-mitigation best practices, flood depth

Three Flood-Mitigation Best Practices That Could Help Houston Region

On 3/22/23, I attended a lunchtime seminar on flood-mitigation best practices hosted by FEMA Region 3 (Philadelphia, Baltimore, Washington DC). The topics covered included building hazard-mitigation plans, resiliency hubs, and flood awareness programs.

The seminar showed dozens of excellent thought-provoking ideas – too many to list in one post. But three in the last category (awareness) really jumped out at me. I will share them below.

It Was How Deep!

This bright display below in a little pocket park shows the depth of flooding during historical and statistical (i.e., 100-year and 500-year) floods. The historical floods go back to 1937.

Image courtesy of FEMA

That will certainly keep people from forgetting.

How Deep Could It Get at My Home or Business?

Flood Depth Grids are a related idea. They go far beyond the types of flood maps we currently rely on that show flood frequency zones, like the 100-year (1% annual chance) flood zone. These answer the question, “How deep would the water get in a 100-year flood?” In this case, 2.88 feet of water would invade the building shown beneath the pointer.

Image courtesy of FEMA

This gives people additional useful information they can use to protect their homes and businesses from flood losses. For instance, how high do I need to elevate my home? Or how high do I need to elevate critical machinery used in my business? That’s far more useful than just knowing whether you’re in a zone that has a 1% annual chance of flooding.

How Much Damage Could I Expect?

The flood-mitigation best practice took that flood-depth information to the next level. It answers the question, “If we get a 100-year flood, how much damage would it do to my structure?”

The screen capture below shows a highlighted home on the right. The box on the left shows the assessed value of that home. And at the bottom in blue, it shows the estimated damage in dollars to that structure based on a flood that deep.

Image Courtesy of FEMA

Good or Bad for Property Values

Not everyone will like these ideas. Some might say they could affect property values negatively. But they also could affect property values positively. How? By giving people valuable information they need to protect themselves.

For instance, some people may feel they don’t need flood insurance. Two thirds of the people flooded in Harvey felt that way. But seeing those brightly colored markers dangling at the height of a basketball hoop could motivate you to get flood insurance. And that could protect your neighborhood from abandoned, derelict homes like we still see all over Houston five years after Harvey. All said, I’d personally rather know than not know.

These best practices could help in another way, too – by motivating home and business owners to keep up the pressure on political leaders to mitigate flood risk. Going a few years without a flood can lull people into believing their risk has been mitigated when it hasn’t.

Personalizing Risk

Getting a couple feet of water in my house sounds bad. But losing $168,700 dollars in the process really grabs my attention!

If you saved $200 dollars per month, it would take 500 months (41.6 years) to save just $100,000. During that time, you would have a 34.2% chance of experiencing a hundred year flood. Yep! More than one in three! Check out this flood risk calculator by the National Weather Service.

That kind of knowledge makes people think much harder about how much flood risk they take on.

MAAPnext Will Provide Similar Information

Harris County Flood Control District (HCFCD) currently has an ongoing effort called MAAPnext. It will provide similar information to residents in Harris County.

However, FEMA is reportedly still vetting all the LIDAR data and calculations. FEMA should release the new information sometime this year. They will not pin a date down closer than that.

Posted by Bob Rehak on 3/27/23

2036 Days since Hurricane Harvey