Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Improved remote mapping of disaster zones

28.10.2003


Comparison of various types of remote sensing data over the Tsaoling landslide within 18 months of the September 1999 magnitude 7.6 Chi Chi earthquake in central Taiwan.

a) Surface classification map made from radar scattering mechanisms obtained through analysis of airborne L-band (0.25 m wavelength) Synthetic Aperture Radar (SAR) polarimetry (obtained September 27, 2000). Purple = bare surface, green = forest, black = other (including missing data).

b) Grayscale C-band (0.06 m wavelength) image of vertically-polarized backscatter SAR intensity (obtained September 27, 2000).

c) False-color image of Landsat 7 Thematic Mapper (TM) data (February 2001). Green areas are forested, the purple areas are the landslide source area and debris apron, dark areas in the lower half of image are lakes impounded by landslide. Vegetation regrowth is occurring on the debris apron 18 months after the landslide. Compare with radar classification map in a),

d) Indian Research Satellite visible band panchromatic data (October 31, 1999) obtained within six weeks of the landslide. The landslide is the light colored


Columbia researchers develop "fingerprinting" techniques for SAR mapping

Research by scientists at the Lamont-Doherty Earth Observatory at Columbia University shows that Synthetic Aperture Radar (SAR) polarimetry is a more superior technology for rapidly identifying disaster zones than the currently used optical remote sensing technologies, such as Landsat and SPOT. Their findings are published in the Journal of Geophysical Research, and coincide with an opportunity to outfit satellites scheduled for deployment in 2004 with SAR polarimetry instruments.

Rapidly assessing land damage and responding to natural disasters is key to saving lives. SAR mapping has a clear advantage over optical mapping-the results are not hindered by darkness, clouds, or the smoke and dust frequently associated with disaster zones. This new SAR research marks the initial step in developing radar-based maps of damaged landscapes that can be rapidly provided to rescue workers.



Kristina Czuchlewski and Jeffrey Weissel, Lamont-Doherty Earth Observatory at Columbia University, and Yunjin Kim, Jet Propulsion Laboratory at California Institute of Technology, have developed a classification system for turning the data acquired by SAR into detailed maps depicting landscape elements such as water, vegetation, rocks, and elevations on a per-pixel basis (i.e. for areas as small as 5 x 5 m).

Czuchlewski et al. evaluated the effectiveness of using SAR polarimetry by mapping the massive Tsaoling landslide that resulted from the 1999 earthquake (magnitude 7.6) in Taiwan, damaging highway transportation systems and isolating communities in the area. The Tsaoling landslide slid into the Chingshuichi Valley killing 34 people and requiring rapid construction of a new road to facilitate rescue efforts. Debris covered about 1.3 square miles of the Valley floor, damming the river and forming an artificial lake that had to be drained to avoid the possibility of dam failure during the monsoon rains.

"Our SAR polarimetry data was taken one year after the Tsaoling landslide occurred. When you compare this map to the one generated from the Landsat optical data just 5 months after ours, we find SAR polarimetry to be equally proficient, with the critical added advantage of not needing clear skies to get an image," said Kristina Czuchlewski, Doctoral Candidate, Department of Earth and Environmental Sciences, Columbia University.

The researchers currently utilize NASA’s AIRSAR DC-8 aircraft to collect SAR polarimetry data. Electromagnetic energy is transmitted from the air to the disaster zone and measures the electric field backscatter. This backscatter is then further processed to determine scattering mechanisms, or the "fingerprint," of the surface materials. The different types of scattering mechanisms are applied to the various elements of the terrain. For example, backscatter from bare, rough surfaces generally consists of a single "bounce" back toward the receiving antenna. In contrast, backscatter from leafy trees is diffuse, becoming more random as the radar wave interacts with the trunks, branches and leaves of the canopy. These fundamental properties of the surface can be easily extracted from fully-polarimetric SAR because this type of data records the amplitude and phase of the backscattered electric field, allowing us to measure the organized and random bounces occurring within each pixel. Optical imagery, on the other hand, detects these different surface cover types based on their electromagnetic signature at very short wavelengths. Instead of scattering, optical techniques measure reflectance, a property that is strongly disturbed by the atmosphere and dependent on the sun’s energy.

Lamont-Doherty Earth Observatory researchers are also conducting studies to apply SAR polarimetry mapping to other natural disaster sites, including those devastated by wildfires and lava flows.

"If carried aboard a fleet of robotic, unmanned aerial vehicles (UAVs) instead of on satellites, SAR polarimeters could be rapidly deployed in a cost effective way to disaster sites anywhere on the globe. We could take advantage of the long endurance of UAVs to monitor the development of emerging disasters such as floods, wildfires and volcanic eruptions. In this way, SAR-based disaster response technology could play a vital role in evacuating populations placed at risk by many different kinds of natural disasters," said Jeffrey Weissel, Doherty Senior Scholar and leader of the research team at Lamont-Doherty Earth Observatory.



The Tsaoling landslide research was supported by the National Aeronautics and Space Administration (NASA) Solid Earth & Natural Hazards program and an Earth System Science Fellowship award.

Lamont-Doherty Earth Observatory

The Lamont-Doherty Earth Observatory, a member of The Earth Institute at Columbia University, is one of the world’s leading research centers examining the planet from its core to its atmosphere, across every continent and every ocean. From global climate change to earthquakes, volcanoes, environmental hazards and beyond, Observatory scientists provide the basic knowledge of Earth systems needed to inform the future health and habitability of our planet. For more information, visit www.ldeo.columbia.edu.

The Earth Institute

The Earth Institute at Columbia University is the world’s leading academic center for the integrated study of Earth, its environment, and society. The Earth Institute builds upon excellence in the core disciplines-earth sciences, biological sciences, engineering sciences, social sciences and health sciences-and stresses cross-disciplinary approaches to complex problems. Through its research training and global partnerships, it mobilizes science and technology to advance sustainable development, while placing special emphasis on the needs of the world’s poor. For more information, visit www.earth.columbia.edu.

Mary Tobin | EurekAlert!
Further information:
http://www.ldeo.columbia.edu/
http://www.earth.columbia.edu

More articles from Information Technology:

nachricht Underwater acoustic localization of marine mammals and vehicles
23.11.2017 | IMDEA Networks Institute

nachricht NASA CubeSat to test miniaturized weather satellite technology
10.11.2017 | NASA/Goddard Space Flight Center

All articles from Information Technology >>>

The most recent press releases about innovation >>>

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

Im Focus: Frictional Heat Powers Hydrothermal Activity on Enceladus

Computer simulation shows how the icy moon heats water in a porous rock core

Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Underwater acoustic localization of marine mammals and vehicles

23.11.2017 | Information Technology

Enhancing the quantum sensing capabilities of diamond

23.11.2017 | Physics and Astronomy

Meadows beat out shrubs when it comes to storing carbon

23.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>