Hurricane Harvey provides lessons learned for flood resiliency plans

ScienceDaily | 4/10/2019 | Staff
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ASU researcher Manoochehr Shirzaei of the School of Earth and Space Exploration and former graduate student and lead author Megan Miller (now a postdoctoral researcher at the Jet Propulsion Laboratory, California Institute of Technology) used satellite data to map the Houston-Galveston area impacted by Hurricane Harvey to understand why the flooding was so severe and widespread. The results of their study have been recently published in the journal Remote Sensing of Environment.

For their study, Miller and Shirzaei mapped the Eastern Texas area of Houston-Galveston impacted by Hurricane Harvey using satellite radar data collected from the European Space Agency's Sentinel-1 A/B satellites and Japan Aerospace Exploration Agency's Advanced Land Observing Satellite. From this data, Miller and Shirzaei then compiled a snapshot of the extent of standing water in the area following the hurricane.

Land - Subsidence - Land - Surface - Area

They also measured land subsidence (how much the land surface moves downward) for the area before the storm using space-borne Interferometric Synthetic Aperture Radar (InSAR), a radar technique used to generate maps of surface deformation using differences in the phase of the waves returning to the satellite. The technique can measure millimeter-scale changes in deformation over spans of days to years.

"Earth-orbiting radar satellites provide us with an opportunity to map areas when other techniques fail due to cloud coverage and lack of ground access to the area of the disaster," says Miller.

Satellite - Data - Miller - Shirzaei - Areas

In analyzing the satellite data, Miller and Shirzaei were surprised to see that large flooded areas fell outside the Federal Emergency Management Agency (FEMA) designated 500-year flood zones. "This highlights the need for revising both flood hazard zone maps and flood resilience plans in coastal regions," warns Shirzaei.

Through this analysis, they found land subsidence in the Houston-Galveston area of more than 0.19 inches (5 millimeters) per year in...
(Excerpt) Read more at: ScienceDaily
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