Taxonomy term

flood

Small floods can carve big canyons

Through the early 20th century, geologists argued over how the giant canyons of the Channeled Scablands in Eastern Washington were formed. Ultimately, a theory proposed by J Harlen Bretz in the 1920s — that the canyons were carved by catastrophic, short-lived outbursts of floodwaters unleashed when natural dams holding back glacial lakes collapsed — was shown to be correct. Controversy still exists, though, about the size of these ancient floods.
 

03 Feb 2017

A story in the sediment: Emperor Yu's "Great Flood" may have been real

Ancient Chinese texts re-count the story of a great flood on the Yellow River some 4,000 years ago and Emperor Yu’s heroic efforts to dredge and redirect floodwaters, thereby taming the prolonged and catastrophic floodwaters and setting the stage for the agricultural boom that followed. His success is said to have proved a divine mandate for establishing the Xia dynasty, the first in China’s history. But in the absence of geological evidence for such a flood, scholars have long disagreed as to the veracity of the story.

13 Dec 2016

Earthworms build big mounds to escape floodwaters

When researchers looking for archaeological remains in satellite imagery came across unidentified mounds — some as tall as humans — in the seasonally flooded wetlands of northern South America, they found a landscape shaped not by ancient civilizations but, rather, by modern earthworms.

26 Aug 2016

Geomedia: Books: 'Floodpath' recounts the deadly collapse of California's St. Francis Dam

The catastrophic collapse of the St. Francis Dam, located 80 kilometers north of downtown Los Angeles and east of the town of Santa Clarita, just before midnight on March 12, 1928, claimed more than 400 lives when towering floodwaters destroyed homes, bridges and farmland, as they swept through downstream communities. The disaster was initially blamed on the failure of the west abutment, anchored in soft conglomerate rock. Additional studies have revised this explanation, with recent research citing other geologic and design factors that likely contributed. Regardless, the collapse effectively ended the career of William Mulholland, the self-taught engineer whose 1913 Owens Valley Aqueduct made the explosive growth of Los Angeles possible. Yet, despite the magnitude of the disaster and its impact on local and national policy, it has been almost entirely forgotten, except by a few historians.

08 Jun 2016

Coastal cities will see regular flooding

Rising sea levels will likely lead to regular flooding in most coastal cities in the future, according to a study conducted by the National Oceanic and Atmospheric Administration (NOAA). The report, which used tide-gauge records to chart annual flood rates, showed that these rates have increased substantially in the past 50 years and projected that a majority of U.S. coastal areas will likely experience 30 or more days of flooding each year by 2050.

 
03 Apr 2015

Can dam releases restore river ecosystems?

Scientists and dam managers are studying how the very dams that disrupt river ecosystems can be used to restore them using controlled releases of water.

18 Mar 2015

The '100-year flood' fallacy: Return periods misleading in communication of flood risk

The “100-year flood” is a familiar term to anyone who lives in a flood-prone area or has ever looked at a flood map before buying homeowner’s insurance. Return periods, or recurrence intervals, like this are standard parlance for describing the magnitude and potential hazard of floods, as well as other hydrologic events like storms and droughts. Although such terms have long helped policymakers and the public try to make sense of severe weather, one researcher suggests they may confuse the issue more than clarify it.

11 Jan 2015

Better flood forecasts eyed from space

Satellite measurements of total water storage in river basins — including surface waters, snow, groundwater and soil moisture — may help indicate, months in advance, whether those basins will be predisposed to major flooding, according to new research published in Nature Geoscience. Thus, they could help improve on conventional flood forecasts, which are often based on shorter-term weather forecasts combined with incomplete estimates of basin saturation and offer abbreviated lead times for predictions.

09 Dec 2014

Mississippi sand still abundant

Flood control measures along the Mississippi River have likely saved countless lives, but the effects of upstream dams and containment on the river’s delta have been ecologically catastrophic: In the past 80 years, more than 5,000 square kilometers of wetlands along the Louisiana coast have been starved of vital sediment and drowned. Now, researchers have found that the lower river contains a significant reservoir of the sand needed to mitigate land loss at the river’s mouth — if  it can be diverted downstream.
 

01 Sep 2014

When water, gravity and geology collide: Firsthand observations of the impacts of the 2013 Colorado floods

Around almost every bend in the road on our tour of the Colorado Front Range and points downstream in the weeks after the September floods, the physical devastation confronted us like a punch in the gut. Even though we had all seen graphic images on the news, observing the destruction firsthand, especially from a geologic perspective, was truly stunning and humbling.

21 Jan 2014

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