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We’ve scoured the Earth to bring you this week’s EarthWord...

EarthWords is an on-going series in which we shed some light on the complicated, often difficult-to-pronounce language of science. Think of us as your terminology tour-guides, and meet us back here every week for a new word!

Image shows scour damage on a bridge
Contraction scour and abutment scour at the upstream right abutment at a bridge over Battle Creek in South Dakota following a flood event in August 2007.Public domain

The EarthWord: Scour


  • Although we searched hard for this EarthWord, that’s not the definition we’re going with today. Instead, we’ll be looking at the version of scour that affects bridges and other infrastructure.

  • Scour occurs when water erodes the sediments that surround the base or support structures for bridges, roads, and other man-made buildings.

  • Scour is often caused by fast-moving water, so scour often occurs during floods.


  • Scour originates from the Latin excurare, which meant “to clean off.”

Image shows a graphic of water scouring out sediment near a bridge support
This graphic shows how scour occurs.

Use/Significance in the Earth Science Community:

  • Scour is a big concern for infrastructure managers, as it’s one of the primary structural threats that bridges face. The U.S. Forest Service, in a 1998 report, said that scour was the single most common cause of highway bridge failure in the United States.

  • The phenomenon of erosion due to flooding is also a significant issue to the field of hydrology, as it can affect the behavior of rivers.


  • USGS studies scour as part of its Office of Surface Water, where we had an entire project dedicated to bridge scour.

  • We’re currently working with the Federal Highway Administration to analyze the effectiveness of anti-scour installations on bridges and other infrastructure using high-tech tools like lidar and other survey methods.

  • We also often partner with other agencies like the U.S. Forest Service or the U.S. Army Corps of Engineers to do studies on bridge scour following significant floods.

Next EarthWord: On the 1st day of summer, we’ve got an EarthWord that’s a fan-just not the cooling kind...

Hungry for some science, but you don’t have time for a full-course research plate? Then check out USGS Science Snippets, our snack-sized science series that focuses on the fun, weird, and fascinating stories of USGS science.

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