New Device Will Help Assess Snowmelt, Predict State Water Supply

Apr 29, 2016

The ability to assess water supply is becoming increasingly important, especially since data shows statewide reservoir storage is lower than last year. Utah State University soil scientists and climatologists have created a device to track snowmelt, that could lead to better assessments on water supply. 

    

It’s called a heat pulse probe and it’s a new way to track the amount of water coming out of snowpack. 

“Basically it fires a heat pulse for eight seconds and then you measure the temperature near the needle for another two minutes," said Dr. Scott Jones, a soil scientist from the department of plants, soils and climate at Utah State University. "We have a model that describes this heating in the soil and you fit the model to those temperature rise measurements. The parameters that are fitted are basically describing the thermal conductivity and the thermal diffusivity of the soil.” 

Jones said there is not a lot of historical data on soil moisture in mountain settings.

"We’re interested in soil moisture in the mountains because one of the aspects of the soil and the vegetation on the surface is that it forms the bottom boundary for all of the weather and climate interactions, and so understanding that boundary becomes quite important for getting better estimates of climate change and weather," Jones said.  

Researchers hope the sensor will improve knowledge and understanding about how much water will be available in the coming year by measuring the water that comes out of the snowpack in real-time. Researchers have deployed the probe in the T.W. Daniel Experimental Forest up Logan Canyon and have been experimenting with it for the last decade. Although the probe has the ability to track water coming out of snowpack, it can't quite do everything a snow telemetry site or SNOTEL site does. 

"But at that lower cost, you could probably get a better idea of the spatial distribution of the infiltration of water," Jones said.

Data shows statewide reservoir storage is lower than the previous year.

Simon Wang, an associate professor of climate, meteorology and weather forecasting added it is important to measure the snowmelt down to a certain precision in order for water managers to infer how much water they will get once the snowpack melts. 

The snowmelt has been monitored for years, it's just not very widespread in resolution, Wang said. 

"In the process you have to consider, for example, how much precipitation has fallen and how much of that translates into snowpack," Wang said. "If we have this much snowpack how much of that will get into streams, rivers and dams — that water they can keep?" 

Three consecutive years of drought in Utah have led to dryer soil conditions. Wang said the state finally got a decent amount of snowpack this year, which is supposed to allow for more streamflow. 

"After three years of drought, if you think linearly, soil moisture would be dryer than normal, so it really can stop the waters from going into downstream," Wang said.

Because of this, even though snowpack might be at an average this year, the soil moisture, groundwater and reservoir storage numbers will take longer to come back to a normal value, Jones said.

Researchers are looking at other ways to use the probe, including examining soil heat flux — the energy that goes into the soil — to measure snowmelt. Beginning next year, the device will be put in the hands of other researchers so they can continue to develop it.