Taxonomy term

flood

No river meant no floods for ancient Indus settlements

Large Middle Eastern rivers like the Nile, Tigris, Euphrates and Tiber were critical for the development of early urban societies in Egypt, Mesopotamia and Ancient Rome. And researchers have long thought that the rise, and eventual decline, of cities in the ancient Indus Civilization, which spread across about 1 million square kilometers of what’s now northwestern India and Pakistan from roughly 4,600 to 3,900 years ago, also depended on major rivers, namely those emerging from the Himalayas. But a new study looking at river sediments from the time of the civilization and earlier suggests that wasn’t the case for every ancient Indus city; some may have benefited from being farther away from large rivers and their periodic floods.

01 Apr 2018

Both urban flooding and rural drying to intensify

In a comprehensive global analysis, including data from more than 43,000 rainfall stations and 5,300 river monitoring stations in 160 countries, researchers report that global rainfall is increasing, likely due to warming air temperatures that allow more moisture into the atmosphere, causing more intense rainfall. Rural areas tend to absorb excess water during storms, preventing widespread flooding in rural zones, but between storms, rising temperatures also mean more evaporation from exposed soils, creating drier conditions over the long term, the team noted in Scientific Reports. Meanwhile, in urban environments, more intense rainfall often overwhelms stormwater catchments in places with less exposed soil, leading to a higher incidence of flooding.

11 Dec 2017

Magnetic method dates glacial floods in Iceland

In Iceland, volcanoes buried under glaciers occasionally melt huge quantities of ice, setting off massive glacial floods called jökulhlaups. Dating past jökulhlaups helps geologists better understand the eruptive history of Iceland’s many active volcanoes, which, in turn, sheds light on future volcanic hazards. But such dating is no easy task. A new study of magnetic minerals preserved in large boulders moved by floodwaters might provide a new tool in the effort.

07 Jul 2017

More than a nuisance: Over time, small floods cost more than extreme events

Devastating storms like Hurricanes Katrina and Sandy dominate public attention when they hit, causing massive amounts of damage from high winds and waters. But small floods driven by rising seas may end up costing some coastal areas more in the long run. According to a new study published in the journal Earth’s Future, the cumulative property damage from these so-called nuisance floods could eventually match or exceed costs from rare extreme storms.

03 Jul 2017

An economic argument for reframing the geoscientist's role in disaster mitigation

Geoscientists don’t often weigh in on the long-term societal implications of the natural disasters they study — but perhaps they should. Thinking about disasters in the same way economists do might help them do more good.
14 May 2017

Comment: Atmospheric rivers increase water supply in California — but only to a point

Atmospheric rivers can cause floods; their absence can cause droughts. How can water managers adapt to capture and store floodwaters brought by these enormous storms for later use?

10 Feb 2017

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

Pages