Runoff, in the context of environmental and Earth system topics, refers to the portion of precipitation, snowmelt, or irrigation water that does not infiltrate into the soil or evaporate but instead flows over the land surface or through shallow subsurface pathways to streams, rivers, lakes, or coastal waters. It is a central component of the hydrological cycle, governed by factors such as soil permeability, land cover, topography, antecedent moisture, and rainfall intensity. Runoff mediates fluxes of sediments, nutrients, pollutants, and dissolved organic and inorganic constituents, strongly influencing watershed biogeochemistry, aquatic ecosystem function, flood regimes, and water resource availability.
Hiking a picturesque valley or climbing a craggy gorge are among the most exhilarating experiences in nature. As a geologist, I have hiked and climbed some of the most intense terrain in the world, including in the Andes, ...
Environment
Sep 4, 2026
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Canada's capital, Ottawa, was bombarded with 167 millimeters (6.6 inches) of rain in five hours earlier this summer in what the city called a 1-in-200-year event. Close to 5,800 reports of basement flooding followed, and ...
Environment
Sep 3, 2026
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As many cities developed, streams that once flowed on the surface were buried underground to make way for growing infrastructure. However, as heavier rainfall, extreme weather and aging infrastructure place growing pressure ...
Environment
Aug 28, 2026
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The reappearance of Budapest's "Rock of Starvation" is a visible sign of a drought months in the making. IIASA researchers have traced its progression from missing rainfall and parched soils to exceptionally low flows across ...
Environment
Aug 26, 2026
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Microplastics are turning up almost everywhere—from oceans and rivers to soils and sediments—yet far less is known about what happens when they enter freshwater wetlands. Often overlooked in favor of marine and coastal environments, ...
Environment
Aug 26, 2026
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Collecting rainwater from rooftops and using it to spray buildings during hot weather could help cities cut air conditioning use, lower urban temperatures and lessen the impact of heat waves, according to new research from ...
Environment
Aug 5, 2026
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Watersheds that are flatter, drier and warmer are generally more vulnerable to increases in flooding after trees are harvested. Those with greater variation in elevation spread runoff out over time, reducing flood peaks.
Environment
Aug 5, 2026
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The small mountain streams that feed many of the West's rivers may face a much drier future. A new study led by NAU researchers found that groundwater-fed streamflow, known as base flow, has been steadily declining across ...
Environment
Aug 2, 2026
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Coastal cities are at increasing risk of compound flooding events, such as when heavy rainfall and storm surges occur simultaneously during hurricanes. However, the processes that contribute to urban compound flooding aren't ...
Earth Sciences
Jul 30, 2026
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Rowers on the River Po in Turin are battling vast blooms of algae, as high temperatures in northwest Italy and runoff from farms create ideal conditions for rampant plant growth.
Environment
Jul 16, 2026
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