Flood risk is about where you build stuff

The stretch of the Rio Grande in Albuquerque where we worry most about flood risk is called the “Montaño Gap”, a couple of miles on the west side of the river in the center of town where a school, some homes, and businesses are located in lowlands with essentially no levee protection.

There was an interesting discussion Monday at the meeting of the Middle Rio Grande Conservancy District, one of the government agencies with shared responsibility for the problem (we’ve also got a city, a county, and a flood control district with confusingly overlapping jurisdictions) about how to address the problem. We’ve got a $7 million federal grant for new levee work from FEMA, so we’ve got a path forward for this. But it’s interesting to think about why this problem exists, and why we’re asking the federal taxpayers to bail us out of the problem.

“Flood” is a loaded word. Its common dictionary definition involves water flowing over land “not normally submerged” (that’s OED’s version), but we really don’t gear up the use of “flood” until the water’s reaching places where we’ve built stuff. Just downstream of the Montaño Gap (the name comes from a local street name) are stretches of open riparian forest and some sandbar islands that are also occasionally subject to water flowing over “land not normally submerged”, but when the water reaches those spots we have more modest, neutral language. “Overbanking” is the word if anyone notices, but usually when it happens there the only people who notice are water nerds. When the “overbanking” submerged my bike trail last spring, that’s when it became a “flood”.

This suggests that flooding is in part linked to human agency – not just higher water on the weather/climate side, but also the act of building stuff that’s in the way. The problem is that we tend to blame the former (weather) and think less about the latter (our responsibility for building stuff that’s in the way).

The University of California’s Nicholas Pinter published a piece this week that talks about the role of the federal government in helping sort this question. It has to do with federal flood insurance guidelines, which help provide incentives (both good and bad) for where we build stuff:

The biggest problem with flood maps in the U.S. is that they are drawn as “lines in the sand”—implying that there is a flood risk on one side and none on the other. That is a false and dangerous message. The best way to approach a line on a flood map is like seeing a poisonous snake: Don’t panic, but stay well clear.

This issue was handled deftly by the Obama administration. In January 2015, Obama issued Executive Order 13690, which established the new Federal Flood Risk Management Standard (FFRMS). In brief, this standard called for a more cautious approach to construction at the boundaries of flood hazard zones. The approach was flexible and didn’t even require an admission of climate change as being the cause—just more caution.

In Houston, we built a lot of stuff that’s now in the way of water from Harvey running off the land on the way to the sea. That’s a big part of what’s making this event a “flood”.

We’ve had quite a few opportunities recently to rethink this question. Sadly, as  Pinter points out, two weeks ago the Trump administration rescinded the Obama-era executive order aimed at bringing a bit of sanity to the incentives (good and bad) associated with federal flood insurance.

One Comment

  1. In addition the reliance on levees for protection. A lot of the homes along the Brazos (in Fort Bend County) are in levee districts to pay for the construction and upkeep of the levees. So the subdivisions now come with 200 or so foot of the low water state of the river. (Look on google earth at the southern part of Sugarland Tx which backs up to the river) The levees here are not yet long enough to raise the river crests to much at this point, possibly in Brazoria County Downstream where again there a number of subdivisions downstream that have flooded. (Above Richmond/Rosenberg, the river flows thru pretty rural areas)

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