Plans to develop a flood monitoring system in the Texas county hit hardest by deadly floods were scheduled to begin only a few weeks later.

A retired nurse, her son and a family friend say they were lucky to survive last week's flash floods in Texas that killed more than 100 people, including many summer campers.

The Texas Hill Country has been notorious for flash floods caused by the Guadalupe River. Here's why the area is called "Flash Flood Alley."

Rain rushing to the Guadalupe took it from a depth of less than 8 feet to 37.5 feet, a deluge with as much volume as an aircraft carrier over five minutes.

Flash floods last week in Texas caused the Guadalupe River to rise dramatically, reaching three stories high in just two hours.

In what experts call "Flash Flood Alley," the terrain reacts quickly to rainfall steep slopes, rocky ground, and narrow riverbeds leave little time for warning.

With more than 170 still missing, communities must reconcile how to pick up the pieces around a waterway that remains both a wellspring and a looming menace.

As the Guadalupe River swelled from a wall of water heading downstream, sirens blared over the tiny river community of Comfort -- a last-ditch warning to get out for those who had missed cellphone alerts and firefighters going street-to-street telling people to get out.