THINGS TO KNOW: Houston's floods and politics of growth

HOUSTON (AP) - 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.

A look at what's happening:

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MORE EXTREME DOWNPOURS

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.

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RUNAWAY DEVELOPMENT

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.

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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.

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HOUSTON'S DRAINAGE DEFICIT

Detention ponds that capture stormwater and pipe it out slowly have been Houston's preferred approach to flood control, along with drainage improvements. But critics say developers skimp on detention systems.

"Areas that never flooded before now flood in the smallest event," said Ed Browne, chairmen of the citizens' group Residents against Flooding.

Harris County Flood Control Director Mike Talbott wishes he had $200 million a year - more than triple his $60 million budget - to improve drainage. A key half-billion-dollar project is seven years behind schedule.

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BIG DONORS

Commercial developers are big players in Houston politics.

Nearly half of the $313,000 that Harris County's top elected official, Judge Ed Emmett, collected in campaign contributions in the first half of 2014 came from engineers, builders, developers and real estate interests. Emmett, who won re-election in November 2014, denies giving favorable treatment.

Last December, when Houston Mayor Sylvester Turner won a runoff, more than a quarter of the $726,000 in contributions to his campaign came from developers, engineers, buildersˆ and real estate interests. Turner's spokeswoman, Janice Evans, said projects to improve drainage in Houston are chosen solely based on where need is greatest.

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WHAT COMES NEXT

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.

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Borenstein reported from Washington, D.C.

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