It’s time to talk about flooding

flood risks by deborah

No, seriously — it’s time to talk about flooding.

The fall rains saturated the ground. In the past 48 hours Austin has seen more than two inches of rainfall in places such as the Onion Creek area, with nearly three-and-a-half inches in portions of the Hill Country where runoff feeds the Highland Lakes, which are nearly full. Rains are expected to continue through the week and, though the heaviest is probably behind us, even a relatively modest downpour in the right place could cause flooding.

El Niño is still spinning the Pacific, as well, and will likely continue into summer,  producing a rainy spring, most forecasters say. And — March is traditionally a month that brings severe storms.

“When I talk about severe storms, I’m referring to storms that can produce damaging winds, large hail, tornadoes and even flooding,” Bob Rose, a meteorologist with the Lower Colorado River Authority, said in a recent blog post. Add El Nino to the typical pattern and you get a strong possibility of a spring “with more severe storms than we’ve seen” in recent years.

The LCRA manages the Highland Lakes, a series of connected bodies of water that are dammed to limit flooding. There is no imminent flood threat, according to the agency. But lakes Travis and Buchanan, which rise and fall and are often used to absorb flooding, are 95 percent and 83 percent full, respectively. A good rainfall in the right place can cause a rapid rise “with very little warning,” said John Hofmann, who oversees river operators for the agency.

That can put homes and businesses along the lakes at some risk. The agency must strike a balance during a flood between releasing water down the lakes and ensuring it does not release so much it imperils downstream communities such as Austin, which the dams were built partly to protect. The agency recently advised property owners to repair docks and generally prepare for the possibility of flooding.

Other areas are also at risk in “flash flood alley.” The soil is still plenty moist, diminishing its absorptiveness and putting places such as Southeast Austin’s Onion Creek neighborhood, which was hit with devastating floods in 2013 and 2015, at greater risk. Last Memorial Day weekend, San Marcos was hit with floods so devastating that the city still has not fully recovered. That led the U.S. Department of Housing and Urban Affairs to recently take the unusual step of earmarking $25 million relief to the city, specifically, along with Houston ($67 million) and the rest of Texas ($51 million).

Though floods are generally the most devastating creation of Central Texas storms, they can bring other damaging phenomenon. One day to watch this month: March 25. That’s a day to park the cars in the garage, if possible, because the hail that tends to come in spring has a nasty habit of hitting hard that day. Three of the six costliest hail storms in Austin history, Rose said, struck on March 25.