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Rain isn't always good news amid a major drought

A school bus drives across a bridge over a roaring creek
Gabriel C. Pérez
/
KUT
A school bus drives across a bridge over Blunn Creek in South Austin during heavy rain last month.

As Texas experiences various levels of drought across the state, Austin has plenty of rain in the forecast. But rain during a major drought isn't always good news.

Heavy rain during a drought can increase the risk of flooding, and Austin is a little too familiar with that. The city sits in the middle of “flash flood alley,” a stretch of land that runs from San Antonio to Dallas, one of the most flood-prone regions on the continent.

Many things contribute to Austin’s flood risk, according to Kevin Shunk, the city's floodplain administrator.

Austin lies on the Balcones Escarpment, a fault line that separates the Hill Country from the coastal plains. Shunk said the moist air from the Gulf of Mexico can wreak havoc on weather systems in Austin.

On top of that, parts of Austin have low levels of topsoil, which means water cannot effectively soak into the earth when there are large amounts of rain. Droughts only worsen this: The ground hardens and dries, creating an impervious surface that can’t absorb water. When it rains for a prolonged period of time, the water accumulates and has nowhere to go.

“We are designing urbanized areas in a way that we expect the landscapes to be our natural sponge. But they're not becoming those buffers.”
Dev Niyogi, professor at UT Austin

Although creeks do a good job of collecting water, Shunk said, they often can’t hold the amount needed to prevent buildings and roadways from flooding.

Dev Niyogi, a professor at UT Austin, specializes in climate adaptation and smart cities. He said one issue with flood mitigation and how we build cities is relying on the surrounding natural land.

“We are designing urbanized areas in a way that we expect the landscapes to be our natural sponge,” he said. “But they're not becoming those buffers.”

Niyogi said Texas is a water-sensitive region and cities in flash flood alley should be structured to benefit from downpours rather than suffer.

“That it rains, we cannot control," he said, "but once the rainwater reaches the ground, it is completely in our control.”

Recurring and prolonged droughts can permanently change a landscape. Slowly, the ground becomes less and less absorbent, and vegetation struggles to grow. When it finally rains, there’s a higher probability of runoff than absorption. This causes topsoil to erode further, leaving behind rocky layers and even less permeable earth. Without vegetation to intercept rain and bind soil with roots, the pattern repeats itself.

Niyogi said creating more pockets of lush vegetation to absorb and redirect water is a step in the right direction.

Building widespread rain-catching and storing systems is another step. Rather than water going into a storm drain where it’s treated as waste, Niyogi said, it should be used to ecologically "recharge" a drought-stricken region.

“With proper use of data, planning tools and working with your policymakers," Niyogi said, "we can benefit from the rain that comes in to recharge the ecosystem and not let it become a hazard.”

The City of Austin has taken precautions to mitigate risk by identifying areas prone to flooding. Unfortunately, Shunk said, those areas are "across the entire city."

“I’m sure that it’ll flood again in Austin,” he said. “I don’t know when, I don’t know where, but it will flood again in Austin. And when it does, we hope that we are prepared.”

The city offers these tips for residents ahead of the next flood watch:

  • Be alert to your surroundings.
  • Monitor local media.
  • Avoid driving.
  • Stay away from creeks, trails, culverts, ponds and other drainage infrastructure.
  • If water starts to rise, seek higher ground. This may mean getting on your roof.

If you must drive:

  • Check ATXfloods.com for known, flooded roads.
  • Avoid low water crossings.
  • Actively look for water over the road.
  • Turn around if a road is barricaded or if water is over the road. Keep in mind that the road may be heavily damaged underneath the flood water.

Austinites can also visit the ATX Flood Safety website or floodplain maps and resources on flood preparedness and safety.

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