Victims Had No Chance

Deadly Floods: Climate, Policy Failures in Fatal Collision

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There's no such thing as a natural disaster, geographers like to say – a reminder that human choices turn hazards into tragedies. The Texas flash floods this weekend that left more than 100 dead, including many children, offer a stark illustration.

Here is a look at the intertwined forces that amplified this storm's impact: Texas's Hill Country sits in an area known as "Flash Flood Alley," said Hatim Sharif, a hydrologist at the University of Texas at San Antonio.

Warm Gulf air rushes up the Balcones Escarpment – a line of steep hills and cliffs that arcs southwest down from near Dallas – cools and dumps torrents onto thin soils that quickly give way to bedrock. Runoff then funnels through a dense web of creeks.

"Water will rise very, very quickly, within minutes or a few hours," Sharif said.