July 19, 2012 By Brian Heaton
When heavy rains trigger rising waters in Austin, Texas, an early warning system is giving city officials and residents a heads-up on what to expect.
Called FEWS — Flood Early Warning System — the technology provides predictive modeling based on real-time data. With precision flood maps, decision-makers and emergency personnel can make timely evacuation decisions and potentially save more lives.
Although a version of the system has been online since 1985, FEWS operators only had access to numbers on a screen to indicate flood danger. In the old system, there weren’t maps of flooded locations or automated reports showing road closures.
Work began on the new version of FEWS in 2008 and was completed in 2010. The new system features a city-built Supervisory Control and Data Acquisition (SCADA) running via a human-machine interface. The SCADA interface incorporates flood-related information from a variety of sources to determine, up to six hours in advance, which roads will flood and what areas need to be evacuated.
Data is compiled by the system through an assortment of sources, including a privately hosted gauge-adjusted radar rainfall system, which pulls in rainfall data from the National Weather Service Doppler radar and then adjusts the radar and data based on what a network of 4,883 virtual ground rainfall gauges in the Austin area are recording.
A vendor-hosted hydrologic and hydraulic model runs every 15 minutes using the gauge data that shows peak stage and flow of flood waters at various locations throughout Austin. The models are then calibrated against sensors operated by the U.S. Geological Survey (USGS).
The advanced warning system is a far cry from what existed in years past. In 1998 and 2001, the city had to evacuate hundreds of citizens because of flooding. Since predictive modeling wasn’t yet in place, the evacuations occurred at the height of the flood waters.
That shouldn’t happen again. FEWS now provides Austin with much greater lead time if a flood situation begins brewing in the city.
Belinda Perez, an IT manager for Austin, said the large number of rain gauges out in the field and the telemetry they send into FEWS is the key cog in determining if there’s a potential flood situation. Perez explained that the mapping system and observation of the USGS data allows city officials to create a dependable prediction based on past events.
“We will look at the historical data and that will tell us based on what we are seeing from the USGS, how much water is coming and will help us predict what could potentially happen,” Perez said.
The system apparently has been a success. According to a narrative about the system prepared by the city, since FEWS’ launch in 2010, there have been no vehicular deaths in Austin due to flooding. The only exception happened two years ago, when a driver went through a barricaded road during Tropical Storm Hermine.
FEWS involves many data sources and a variety of people rely on the modeling to do their jobs. So coordinating the project in 2008 was a challenge, according to Perez. She said IT staff and the city’s engineers weren’t communicating well at the time.
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