Better Forecasting

March 17, 2000

Probably for as long as people have been on Earth, we’ve been trying—mostly unsuccessfully—to predict the weather. We’re getting better at it, though, and recently took a huge step in safeguarding ourselves from one of the worst types of flood disasters.

The more settled our communities, the more entrenched our buildings and roads and infrastructure, the more vulnerable we are to damage from flooding. We get new and devastating examples almost every year.  In 2004, a relentless series of hurricanes moved through Haiti and the Bahamas and into the US: Charley, Frances, Ivan, and Jeanne. Less than a year later, in August 2005, we had Katrina. Late in 2006, massive storms hit the Pacific Northwest.

Floodplain maps, master drainage plans, and zoning to keep new construction out of harm’s way are some of the most important tools we have to avert damage ahead of time. Very accurate flood-warning systems are also available to provide information on what’s happening in real time during the event. These automated systems can measure rainfall data, compute flow rates and calculate water elevations at key points, and map out where floods will likely occur. The systems can also trigger alarms when waters reach predetermined thresholds to give stormwater and emergency management staffs as much warning as possible.

Hurricane warning systems, too, have existed for nearly a hundred years in some form or another, from balloon-carried radiometeorographs that measured air pressure, temperature, and humidity to today’s weather satellites, which have been used since the 1960s to help determine which areas should be evacuated ahead of the storm. Near-term forecasting can now give us a pretty good idea of a hurricane’s movements 48 hours in advance.

But as the world realized in December 2004, not all flooding is caused by the weather: Far worse than any flash flood or hurricane, the Asian tsunami was caused by the Sumatra-Andaman earthquake in the Indian Ocean. The tsunami killed, by some estimates, more than 220,000 people. In November, the National Oceanic and Atmospheric Administration and the government of Thailand deployed the first tsunami-detection buoy in the Indian Ocean, the first of 22 planned “tsunameters” that will provide coverage for the entire region affected in 2004.

The system, DART (for Deep-ocean Assessment and Reporting of Tsunami), provides real-time detection, allowing people to be evacuated and resources deployed much as land-based flood-warning systems do. As described by the NOAA, DART will include pressure sensors anchored to the seabed as well as moored surface buoys; acoustic links transmit seismic data from the bottom to the surface buoys, which in turn relay the seismic data—as well as sea-level measurements, as the tsunami wave starts to move across the open ocean after an earthquake—to satellites. The satellites transmit the information to ground stations. Algorithms are used to forecast the height, at specific coastal locations, of the tsunami waves that will later reach land, allowing time for warnings and evacuations of those areas.

DART buoy stations are also in place off US East, West, and Gulf coasts and are planned for eventual placement around the globe. We’ve come a long way since the best means we had for seeing what was coming was scanning the horizon and the sea.  
About the Author

Janice Kaspersen

Janice Kaspersen is the former editor of Erosion Control and Stormwater magazines. 

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