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Amid Drought, Explaining Colorado’s Extreme Floods


Photo retrieved from: www.nationalgeographic.com

“U.S. President Barack Obama declared an emergency for Boulder, Larimer, and El Paso Counties on Friday and the Federal Emergency Management Agency (FEMA) has deployed four rescue teams to the area, the most ever in the state.

Just as troubling as all the damage, Udall says, is that this week’s floods do not fit into the usual pattern of high water in the West.

The floods were not the result of springtime rains or intense summer thunderstorms that quickly dump large amounts of rain in concentrated areas, such as the 1976 Big Thompson or 1997 Fort Collins floods.

“This was a totally new type of event: an early fall widespread event during one of the driest months of the year,” Udall said.

So what explains the anomaly?

Sandra Postel, National Geographic’s Freshwater Fellow, said that the long-term drought that has parched the area and gripped much of the Colorado River Basin over the past 14 years may be partly to blame for the severity of the floods.

Drought tends to harden the soil, she said. When rains do come, less of the water can absorb into the ground, so it quickly runs off the land.

Similarly, fires can lead to worse flooding, because they remove vegetation that can slow down and trap rainfall, Postel said. (See “Fire and Rain: The One-Two Punch of Flooding After Blazes.”) In 2012, the Boulder area was afflicted by theFlagstaff Fire. In 2010, the Fourmile Canyon fire caused damage to Boulder County worth $217 million.”

Read more: National Geographic