Surface-water level refers to the elevation or height of free water surfaces in rivers, lakes, reservoirs, wetlands, or other surface-water bodies relative to a defined vertical datum or local reference point. It is a fundamental hydrologic state variable controlling hydraulic gradients, flow directions, storage volume, and exchange with groundwater and the atmosphere. Surface-water level is monitored using gauges, pressure transducers, radar or ultrasonic sensors, and remote sensing, and is used to derive stage–discharge relationships, flood frequency statistics, and water-balance components. Temporal variability in surface-water level reflects the integrated effects of precipitation, evapotranspiration, inflows, outflows, regulation, and anthropogenic withdrawals.
Communities worldwide rely on reservoirs for drinking water, hydroelectric power, irrigation, and more. These critical freshwater resources are affected by seasonal and long-term changes; water levels in reservoirs can dip ...
Earth Sciences
Mar 31, 2026
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Across much of the Western United States, winter 2026 was the year the snow never came. Many ski resorts got by with snowmaking but shut down their winter operations early. Fire officials and water supply managers are worried ...
Earth Sciences
Mar 25, 2026
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The Sierra Nevada snowpack, the source of nearly one-third of California's water supply, is looking a little like a New Year's resolution: full of hope and promise at the beginning of January, but now struggling with a bothersome ...
Environment
Jan 30, 2026
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What's the shape of water? In 2022, NASA launched the Surface Water and Ocean Topography (SWOT) satellite to answer this question by precisely measuring the height and extent of bodies of water. Virginia Tech geoscientists ...
Earth Sciences
Jan 19, 2026
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When it rains, it pours. And that's good news for California's water supply.
Earth Sciences
Jan 6, 2026
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Seawalls and other unyielding structures meant to keep rising waters at bay and to protect against storm surges can cause other significant harm to the coast, often by disrupting natural processes and accelerating erosion. ...
Environment
Nov 18, 2025
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As summer comes to an end, and if you enjoyed Lake Michigan this summer, you might have noticed lower water levels. While you may wonder about lower water levels, the higher water levels in the past decade continue to have ...
Environment
Sep 12, 2025
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As Great Salt Lake's levels continue to sag, yet another strange phenomenon has surfaced, offering Utah scientists more opportunities to plumb the vast saline lake's secrets.
Earth Sciences
Jul 11, 2025
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Over just two hours, the Guadalupe River at Comfort, Texas, rose from hip-height to three stories tall, sending water weighing as much as the Empire State building downstream roughly every minute it remained at its crest.
Environment
Jul 11, 2025
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The water beneath our feet that we use to bathe, drink and water crops is vanishing faster than ever in the Colorado River Basin, according to a new study.
Environment
Jun 16, 2025
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