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 Construction of practical quantum computers radically simplified
05.12.2016 | University of Sussex

nachricht UT professor develops algorithm to improve online mapping of disaster areas
29.11.2016 | University of Tennessee at Knoxville

All articles from Information Technology >>>

The most recent press releases about innovation >>>

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

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Scientists track chemical and structural evolution of catalytic nanoparticles in 3-D

08.12.2016 | Materials Sciences

Decoding cement's shape promises greener concrete

08.12.2016 | Materials Sciences

Will Earth still exist 5 billion years from now?

08.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>