Water securitySnow science in support of U.S. water supply

Published 23 February 2017

More than one-sixth of the world’s population relies on seasonal snow for water. In the western U.S., nearly three-quarters of the annual streamflow that provides the water supply arrives as spring and summer melt from the mountain snow packs. Right now, predictions of streamflow can vary widely due to limited ground measurement sites. This is one of the reasons scientists and resource managers are interested in a comprehensive view from space of what they call snow-water equivalent — the amount of liquid water contained in snow cover. Scientists use snow-water equivalent to estimate the amount of water that will melt into mountain streams, rivers and reservoirs.

Researchers have completed the first flights of a NASA-led field campaign that is targeting one of the biggest gaps in scientists’ understanding of Earth’s water resources: snow.

NASA uses the vantage point of space to study all aspects of Earth as an interconnected system. But there remain significant obstacles to measuring accurately how much water is stored across the planet’s snow-covered regions. The amount of water in snow plays a major role in water availability for drinking water, agriculture and hydropower.

Enter SnowEx, a NASA-led multi-year research campaign to improve remote-sensing measurements of how much snow is on the ground at any given time and how much water is contained in that snow. SnowEx is sponsored by the Terrestrial Hydrology Program at NASA Headquarters in Washington, D.C., and managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland. The first year of the ground and air campaign takes place in February in western Colorado.

“This is the most comprehensive campaign we have ever done on snow,” said Edward Kim, a remote sensing scientist at NASA Goddard and the SnowEx project scientist. “An army of nearly 100 scientists from universities and agencies across the U.S., Europe and Canada are participating. Our goal is to find and refine the best snow-measuring techniques and how they could work together.”   

Scientists know that they will need multiple sensors to measure the water content in snow.  “No one instrument is perfect,” said Charles Gatebe from NASA Goddard, SnowEx deputy project scientist and senior scientist with Universities Space Research Association. “One of our biggest problems is detecting snow through trees. We will work closely with our ground team to try new techniques to see if we can figure out how to do that accurately.”

Why snow?
NASA notes that more than one-sixth of the world’s population relies on seasonal snow for water. In the western U.S., nearly three-quarters of the annual streamflow that provides the water supply arrives as spring and summer melt from the mountain snow packs. Right now, predictions of streamflow can vary widely due to limited ground measurement sites. This is one of the reasons scientists and resource managers are interested in a comprehensive view from space of what they call snow-water equivalent — the amount of liquid water contained in snow cover. Scientists use snow-water equivalent to estimate the amount of water that will melt into mountain streams, rivers and reservoirs.

Snow also affects and is affected by