Planning, modern mapping keep Virginia a step ahead of natural disasters
By Ana Constantinescu
Related story: Low points of Virginia weather woes
It doesn’t always take waters rushing through the streets to devastate homes or other property. Many times, just a single inch of rain can leave costly damage behind.
According to the National Weather Service, flash flooding and river flooding are the deadliest weather-related disasters in Virginia. During the past three-and-a-half decades, there have been 36 presidentially declared natural disasters statewide, of which almost three in four were floods, according to the Virginia Department of Emergency Management (VDEM).
“I remember going out to the Virginia Tech campus to take pictures after the July 5, 2006, storm in Blacksburg. I was expecting rain puddles and soggy ground. I wasn’t prepared to see a foot of water in places such as the University Bookstore’s parking lot,” recalls Randy Dymond, co-director of Virginia Tech’s Center for Geospatial Information Technology (CGIT) and professor of civil and environmental engineering.
To give Virginians the upper hand against floods and other weather tantrums, and natural disasters, CGIT floodplain specialists and civil engineers led by Dymond are working with the Virginia Department of Conservation and Recreation (DCR) and VDEM.
The CGIT team has coordinated numerous local and regional hazard mitigation plans to make Virginia communities disaster-resistant through planning before disasters, such as floods, winter storms, hurricanes, and earthquakes, strike. And they are updating outdated flood maps for local communities and coordinating statewide efforts to help other communities bring their flood maps up to date.
“We are an interdisciplinary research center that specializes in advanced geospatial data analysis and applications, such as risk assessment, spatial analysis, decision support, and mapping” says Dymond. “So, projects like flood map modernization and natural hazard mitigation are among the things we do best.”
New flood maps
CGIT is replacing the decades-old, paper flood maps that Montgomery and Giles counties and the city of Radford have been using with new, digital maps.
How exactly do flood maps keep us safe from floods? “They tell land developers, contractors, and finance companies where it is safe to build new houses and other structures,” explains Dymond. “Flood maps also allow homeowners to pay the correct flood insurance premium, instead of a standard rate that may or may not reflect the actual risk for flooding.”
Old flood maps become obsolete as new developments, roads, and parking lots are built. Such urban sprawl means that the land loses its natural ability to absorb water and thus to reduce flooding.
“Blacksburg is a good example of a growing town that is gradually losing land uses that naturally defend against flooding,” says Dymond. “While we cannot eliminate flooding altogether, we can be as prepared as possible to limit its costly consequences.”
One of the technologies used by CGIT floodplain specialists is GIS or geographic information systems.
“GIS is a computer-enabled information system that allows users to superimpose different map layers containing a variety of information on top of each other,” says Steve Prisley, co-director of CGIT and professor of forestry. The technology links physical features on the earth to a database of their descriptions, locations, and characteristics.
“Using GIS software, we combine data from topographic surveys and hydraulic models to generate accurate flood boundaries,” says Thomas Dickerson, certified floodplain manager and research assistant at CGIT. “We then compare our results with the latest aerial photography to confirm conditions on the ground.”
New digital flood maps for Montgomery and Giles counties and Radford city are projected to be ready in spring of 2008.
Statewide efforts
Another flood map project underway at CGIT is the statewide Map Modernization Management Support (MMMS) initiative, which the Federal Emergency Management Agency (FEMA) launched on a national scale in 2004.
The MMMS program was created by FEMA to help local communities transform their outdated flood maps into more reliable and easier-to-use digital maps. In addition to actually updating the flood maps, CGIT has managed the challenging task of monitoring floodmap modernization progress in almost 300 Virginia communities since 2004.
“We have created an MMMS website for the local governments and public about the floodplain map modernization program, including information about the status of the new floodplain maps, the National Flood Insurance Program, and a local up-to-date floodplain contact database,” says Rachael Heltz Herman, the environmental GIS manager at CGIT.
The updated and modernized flood data will also be used to create Digital Flood Insurance Rate Maps (DFIRMs) for more than 20,000 communities across the U.S. DFIRMs are special maps on which FEMA has delineated the flood-prone areas along with the corresponding flood insurance premiums applicable to communities.
Assessing Virginia’s risk to natural disasters
When CGIT was founded in 2003, one of the first projects that stood out through scope and magnitude was developing natural hazard mitigation plans for the entire state of Virginia. A CGIT team headed by Dymond and Herman worked closely with VDEM as information was gathered about the potential risks and developed hazard-mitigation strategies for various state facilities, including Virginia Tech’s main campus in Blacksburg.
CGIT created the Hazard Identification and Risk Assessment (HIRA) as a part of the hazard mitigation plans for Virginia. The HIRA report includes information about the risk from such natural hazards as winter storms, floods, wildfire, landslides, wind, hurricanes, or earthquakes. The report also summarizes historic catastrophic occurrences for Virginia, including details about the hazards that contributed to the events and the damage they caused.
“We developed profiles for each of the recorded hazards that occurred in Virginia, including information about their frequency, magnitude, and impact,” explains Herman. Some of the data went back to the mid-1800s, as was the case with hurricanes.
Next, the CGIT team evaluated vulnerabilities using special technologies, such as GIS. “Using GIS, we located nearly 13,000 state facilities and then compared their locations with existing hazard mapping to analyze the buildings’ risk and vulnerability,” says Herman.
Some of the findings of the hazard mitigation analyses are intriguing. For example, Montgomery County seems to be more prone to fires, severe winter storms, and land subsidence than other Virginia counties. Another hazard mitigation study focused on Virginia Tech’s Blacksburg campus found that some of the buildings with the highest risk for flooding are the Eggleston Hall dormitory, the Graduate Life Center at Donaldson Brown, and the University Bookstore.
So, when Dymond photographed the University Bookstore’s parking lot after the violent July 2006 rain storm, he captured a real-life snapshot of CGIT’s natural hazards analysis. “The flooding that occurred in Blacksburg in the 2006 summer gave a whole new meaning to the projects that we develop at CGIT,” says Dymond. “We realized how deeply our work can impact our community.”
