More Intense Rains, Development Worsen Houston Floods

Floods are getting worse and more expensive in Houston, the nation’s fourth-largest city, where entire neighborhoods are often overwhelmed shortly after a heavy rainstorm.

Since 1998, the Federal Emergency Management Agency has paid more than $3 billion in today’s dollars in Houston flood losses. The latest calamity occurred April 18, when floodwaters killed eight people and caused tens of millions of dollars in damage. Some of the victims had been flooded before.

With clay soil and tabletop-flat terrain, Houston has endured flooding for generations.

Climatologists say extreme downpours have doubled in frequency over the past three decades in part because of global warming. Intense downpours – the type that measure at least 10 inches – have doubled in frequency over the past three decades, and scientists say man-made global warming is a factor. Since 1985, rising average temperatures have packed 7 percent more moisture into the atmosphere above Houston, and waters in the Gulf of Mexico have warmed up.

The other main culprit is unrestrained development in the only major U.S. city without zoning rules. Metro Houston has added more than a million people since 1992, while the amount of water-absorbing wetlands per capita has been cut in half. Paved surfaces in Harris County, which includes Houston, increased by well over 25 percent in that period. Houston is the only major U.S. city without zoning, and critics say flood-prevention systems are inadequate because of local leaders’ cozy relations with developers. That combination means more pavement and deeper floodwaters.

An Associated Press Analysis of Federal Data Found:

• If Harris County were a state, it would rank in the top five or six in every category of repeat federal flood losses.
• While repeat federal flood relief payouts average about $3,000 per square mile nationally, they are nearly $500,000 per square mile in metro Houston.
• Six of Texas’ eight federally declared disasters since December 2013 included floods.
• Since the late 1970s, FEMA has made more flood-damage payments in Harris County than in any place outside New Orleans and two other Louisiana parishes also ravaged by Hurricane Katrina.

Mayor Turner has named a “flood czar,” but no initiatives have yet been announced.

Many experts prescribe voluntary buyouts of chronically flooded Houston homeowners – entire city blocks worth – for conversion into water-absorbing open spaces. Other homeowners will seek grants to elevate rebuilt homes above the flood plain.

Flood plain maps that determine eligibility for subsidized federal flood insurance will need to be redrawn – again.

A 2013 presidential directive told FEMA to start using computer modeling to update the maps, but that hasn’t yet become policy.