How melting snow affects underground water reserves
Most of us have strong opinions about snow during the winter. For some, it’s a curse. Others enjoy the recreation heavy snowfall brings. Yet, once warmer weather comes, we tend to forget about those piles of fluffy white stuff that once towered over our driveways.
In mountainous regions, snow cover plays a critical role in water supplies. Typically, melting snow meets with three fates. It can run off the surface of the soil. It can evaporate and return moisture to the air. Finally—and most importantly—it can replenish underground water levels. This process is groundwater recharge.
Changing climate conditions have caused dramatic changes in groundwater levels. “The lower than historically normal snowfall in recent years is one environmental factor that has contributed to the current drought in California,” says Ryan Webb, a Ph.D. student in the department of civil and environmental engineering at Colorado State University.
Webb’s group recently published a study aimed at understanding the changes in soil wetting and drying that occur as snow melts in mountainous, snow-packed regions. The study examined subsurface water content levels in the Sierra Nevada mountains in California. In these regions, soils do not freeze during the winter and remain wet beneath the snowpack.
It’s not easy to measure groundwater levels, due to variability in soil composition and bedrock. In addition, a melting snowpack introduces its own variables. “Because the variability in groundwater recharge is occurring beneath the ground surface, it can be costly to observe,” says Webb. For example, drilling multiple wells at different locations to measure groundwater would be cost-prohibitive—and disruptive.
Instead, the study used a computerized network of moisture sensors—97 in all, buried at various depths. The sensors were located at varying elevations (1,750-2,000 meters) and types of slopes (north, south, or flat). In addition, the study considered the type of tree cover: open, drip edge, or canopy. The researchers took soil moisture measurements directly beneath snow depth measurements, so they could relate these two measures.
Curiously, Webb and coworkers found melting snow could produce highly variable results within the top meter of soil. “One set of sensors could experience quite different wetting and drying dynamics, relative to a sensor only a couple of meters away,” says Webb. This variability persisted at different measurement sites and under different tree cover conditions.
Many soil moisture studies use uniform, one-dimensional models. Webb’s results suggest such models will either over- or under-estimate the amount of groundwater recharge, depending on the location and depth of the sensors used.
Webb concludes that further study will help us understand why groundwater recharge from melting snow is so variable. He adds, “Long-term periods of record could be used to conduct a similar study over a longer timescale.”
Ultimately, these studies will help understand how climate change impacts groundwater supplies—a precious resource in drought-stricken areas of the country.
Read more about Webb’s research in Vadose Zone Journal. The co-authors of the paper are Steven R. Fassnacht and Michael N. Gooseff. Data for this study were provided by the NSF-supported Southern Sierra Critical Zone Observatory.
Public and Science Communications Director
Susan Fisk | newswise
Seismic study reveals huge amount of water dragged into Earth's interior
18.12.2018 | National Science Foundation
A damming trend
17.12.2018 | Michigan State University
Researchers from the University of Basel have reported a new method that allows the physical state of just a few atoms or molecules within a network to be controlled. It is based on the spontaneous self-organization of molecules into extensive networks with pores about one nanometer in size. In the journal ‘small’, the physicists reported on their investigations, which could be of particular importance for the development of new storage devices.
Around the world, researchers are attempting to shrink data storage devices to achieve as large a storage capacity in as small a space as possible. In almost...
The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.
Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...
What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...
A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.
The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...
A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.
Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...
12.12.2018 | Event News
10.12.2018 | Event News
06.12.2018 | Event News
18.12.2018 | Materials Sciences
18.12.2018 | Physics and Astronomy
18.12.2018 | Physics and Astronomy