Aerial system helps predict ‘depth’ of Colorado’s largest reservoir

LOVELAND — Predicting how much water will be available from the American West’s largest reservoir — the snowpack — has taken on new importance because of the changing climate. As a result, new technology enables the predictions to be more accurate, said Jeff Deems, cofounder of Airborne Snow Technologies.

Deems was among the speakers at the annual Spring Water Symposium, an annual event hosted by the Northern Colorado Water Conservancy District.

Deems’ organization conducts detailed flyovers of the water basins in the West. Using LIDAR and other technology, the organization can accurately measure the depth and water content of mountain snow and predict how quickly it will melt.

The data generated supplements what is available from manual snow-tube data gathering and the SNOTEL technology that measures snowpack in a more automated manner. 

The manual method records depth and water content based upon weight of the sample. It depends upon having a person available to collect the sample.

SNOTEL, which began in the 1970s, uses “snow pillows,” which are permanent installations in the mountains. Snow that falls on them can be measured hourly based on depth and weight. 

Both of those systems are limited to the locations where the data is collected, but they offer the benefit of historic data.

The airborne system, which was spun out of NASA in 2019, provides data over an entire basin, not just at SNOTEL points or manual collection sites.

LIDAR — light detection and ranging — uses laser pulses to measure depth of snow as well as the “albedo” or reflectivity. Dust coverage of snow will speed the melt, Deems said. 

The equipment also can measure the density of the snow. Depth multiplied by density determines the snow water equivalent. 

“When you know where the snow is on the landscape, you can better predict melt patterns,” he said. North-facing slopes will melt slower, for example.

The technology and data collected can enable water managers to predict snow melt peaks. If a secondary peak is predicted, then managers can make room in reservoirs to capture it, he said.

Emily Carbone, water resources specialist for Northern Water,said that the district has only two to four SNOTEL stations in each basin. Since 2022, the district has used airborne observations to supplement and help determine how accurate the SNOTEL data is for an entire basin. The new data, she said, helps to set the annual quota of water that will be available, optimizes reservoir operations and optimizes power generation.