As we continue to grieve the loss of so many Hill Country flood victims, there is a lot of information being thrown around.
KSAT wants to remind people what a “100-year flood” actually means.
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STATISTICAL, NOT LITERAL
A 100-year flood is a flood event that has a 1% chance of occurring in any given year, not once every 100 years. It’s calculated using past rainfall, streamflow and topography to estimate flood risk.
That means there could be another catastrophic flood event next year, unfortunately.
Just weeks before the Guadalupe River flooded, 13 people were killed in a flood on the Northeast Side of San Antonio, which is only 20 to 40 miles away.
San Antonians live in Flash Flood Alley. Therefore, it’s important to be prepared.
100-YEAR FLOOD LEVEL CAN CHANGE
The “100-year flood level” is not a fixed benchmark. As the climate warms, storms grow more intense and frequent.
At the same time, land development, especially in floodplains, changes how water flows across the landscape.
Paved surfaces prevent water from soaking into the ground, increasing runoff and raising the flood risk. In other words, what was considered a 100-year flood a few decades ago might now be a 25-year event, or even more frequent.
WHAT CAN WE DO
We cannot prevent floods, but we can do everything we can to stay prepared.
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Know your flood zones and evacuation routes
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Sign up for all emergency alerts
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Stay informed on the latest weather
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