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Colorado Flood Offers Data Goldmine To Scientists

Grace Hood
State Climatologist Nolan Doesken works in his Fort Collins office.

The rainfall that led to September’s floods in Colorado has been described as “biblical.” State Climatologist Nolan Doesken is trying to quantify that description.

Flooded watersheds were dotted with rain gauges. Now that the preliminary deadline has passed for the Colorado Climate Center’s efforts to gather rainfall totals, scientists have precise estimates of rainfall totals.

The precipitation totals are being plugged into a Google Earth Map that can produce maps like the one below.

Credit Credit MetStat, Inc. and Applied Weather Associates in collaboration with CSU, CU and NOAA. / Google Earth
A view of Larimer County precipitation totals.

Inside places the like Four Mile Canyon and the High Park Fire burn zones, Doesken says it was a happy accident that researchers had installed instruments and stream gauges.

Right now one key question is how the storm could have been better predicted. At the National Weather Service in Boulder, forecasters like Chad Gimmestad knew large amounts of rain were coming, but pinpointing exact locations was challenging.

“We didn’t really know until a few hours in advance when the thunderstorms were starting to develop,” he Gimmestad said.

Two months after September’s historic flooding, scientists are evaluating computer forecast models against what happened to see why some of their models failed.

The U.S. Geological Survey is also crunching data that could be used to regulate development and design of future infrastructure in flood plains. The USGS Colorado Water Science Center expects to release this data in the next few weeks.

A project that will take longer is replacing about 24 stream gauges that were damaged in the flooding.

Credit Marisa Lubeck / USGS
Before and after photos of the gauge on the Cache La Poudre River near Timnath, Colo. Relatively minor bank erosion caused this stream gauge to lean into the river and almost wash away. The recording instrumentation stopped working when this happened.

“The USGS is going to a relatively newer design using sensors that are mounted above the water and we use non-contact radar sensors,” said Bob Kimbrough, associate director for the Center. “These sensors are out of the water and aren’t subject to being damaged by high flows.”

Perhaps the most difficult question will be determining what role climate change played in the September floods. Doesken says he can’t finish a presentation on Colorado’s flooding without an audience member asking about it.

“Mostly it’s not related to climate change,” he said. “[It’s] possibly an incremental enhancement, but a small increment.”

Just how incremental? It’s all about where the data leads now, as scientists tally Colorado’s unprecedented deluge.

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