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.

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."

Walston drove from his home to the Center Point Bridge on FM 480 near Highway 27, where he shot video of the river below. He recorded nearly 38 minutes of surging water as it rose over 20 feet, carrying massive cypress trees, debris and even a house.

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.

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.

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.

Emergency responders kept hope alive as they combed through fallen trees and other debris that littered the hard-hit central Texas communities on the fifth day after devastating floods killed more than 100.