Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Roots of deadly 2010 India flood identified; findings could improve warnings

14.11.2012
On the night of Aug. 5, 2010, as residents slept, water began rushing through Leh, an Indian town in a high desert valley in the Himalayas.
Average total rainfall in the area for August is about a half-inch. During this 24-hour period more than 8 inches fell, causing severe damage and leaving 193 dead, hundreds missing and thousands homeless.

“Flash flooding events don’t happen often but when they do they are some of the scariest, most dangerous and quickest natural disasters that can happen,” said Kristen Rasmussen, a University of Washington graduate student in atmospheric sciences. “But now that we know what types of conditions to look out for, flash flood warnings in remote regions of India might be possible.”

Rasmussen and Robert Houze, a UW professor in atmospheric sciences, studied satellite images and what’s called re-analysis data to piece together what happened to create such a torrential downpour. Their conclusions – including that the flash flood was set off by a string of unusual weather events not unlike those that caused devastating flash floods in Colorado and South Dakota in the 1970s – appear in the Nov. 14 Bulletin of the American Meteorological Society.

They found that on three consecutive days clouds formed high in the mountains to the east over the Tibetan Plateau. By itself, that isn’t uncommon, Rasmussen said.

“What’s different in this case is that there was the unusual wind coming from the east and blowing west,” she said. That helped the clouds clump together and build into a larger storm system capable of creating heavy rain over Leh, which is 11,480 feet above sea level.

At the same time, low-level winds carried in moisture from both the Bay of Bengal and the Arabian Sea. “The storm, forming just up the slope, was able to tap into that additional moisture,” she said.

Typically, such large storm systems don’t have the chance to build because each day as the sun sets, the warm air that has helped the clouds form and lift gets cooler. The clouds then die out in the evening. But during those three days of August 2010, the unusual wind blew through the night, spurring the clouds to continue building into a system capable of heavy rain.

Above-average rain fell on the first two days. Since the region typically gets so little rainfall, the soil doesn’t absorb water well.

“The key is that this happened for three successive days. If the third day hadn’t happened or if the first two days hadn’t set the process in motion, there probably wouldn’t have been such a devastating flash flood,” Rasmussen said.

The situation is reminiscent of weather that caused deadly flooding through the Big Thompson Canyon in Colorado in 1976 and the Black Hills of South Dakota in 1972. In all three cases, large organized clouds gathered high in the mountains and drew moisture up the slope of the mountain into the storms.

The resulting heavy rains are uncommon in mountains, where there typically isn’t enough moisture to cause such dramatic rain. They are also more dangerous than storms in the plains, where water can spread more evenly. In the mountains, the water is funneled into valleys where it accumulates into a narrow space and can form a flash flood.

“A flash flooding-type storm could be moved out onto the plains and simply cause rain across a wide area. But in the right place at the wrong time it can be devastating,” Rasmussen said.

Now that researchers have identified these common elements, including organized clouds high in the mountains on the edge of an arid plain with unusual access to moisture, weather forecasters can potentially warn people who could be in danger if a flash flood happens, she said.

There were some differences between the U.S. floods and the Leh incident. For instance, in the U.S., the storms didn’t move very much. In Leh, for three days the storms moved along the Tibetan plateau but all the rain funneled into the valley where Leh is situated.

In addition to viewing satellite images, Rasmussen and Houze examined data created by using observations of actual conditions to adjust forecasts in retrospect. This re-analysis data included information collected from surface measurements and weather balloons that track things like pressure patterns and moisture in the region. The researchers also recently completed a high-resolution modeling study confirming the findings in the paper.

The National Science Foundation and NASA funded the research.
For more information, contact Rasmussen at kristen@atmos.washington.edu or Houze at 206-543-6922 or houze@uw.edu

Vince Stricherz | EurekAlert!
Further information:
http://www.uw.edu
http://www.washington.edu/news/2012/11/13/roots-of-deadly-2010-india-flood-identified-findings-could-improve-warnings/

More articles from Earth Sciences:

nachricht NASA finds newly formed tropical storm lan over open waters
17.10.2017 | NASA/Goddard Space Flight Center

nachricht The melting ice makes the sea around Greenland less saline
16.10.2017 | Aarhus University

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Ocean atmosphere rife with microbes

17.10.2017 | Life Sciences

Neutrons observe vitamin B6-dependent enzyme activity useful for drug development

17.10.2017 | Life Sciences

NASA finds newly formed tropical storm lan over open waters

17.10.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>