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In South Carolina, mapping played a critical role in situational awareness and damage assessments before, during and after the extreme weather event.
In emergency management and disaster response work, decision-makers and frontline staff rely on geographic information systems to help inform their response, including damage assessments and data collection needed to secure federal recovery funding.
In the South Carolina, which saw Hurricane Matthew move up the Atlantic coast last month bringing inland flooding and coastal erosion, local jurisdictions have not only been using GIS tools but also drone aircraft in their response.
Horry County, South Carolina—home to popular resort city Myrtle Beach—purchased drone aircraft on July 1 to more easily monitor beach erosion.
Modeling sand dune shape and contours establishes a baseline beach line, and Hurricane Matthew proved to be the perfect proof of concept.
Using a mapping tool from Redlands, California-based GIS software company Esri called Drone2Map, Horry County created orthomosaics and 3D meshes from still imagery captured from the unmanned aerial vehicle, which was used to survey the county’s 60 miles of Atlantic coastline.
To establish a baseline, the county flew the southern portion of its coast a day before the then-Category 1 storm made U.S. landfall southwest of Myrtle Beach. It did so again a day after the storm renourished the coast. Erosion quantities were calculated comparing the two datasets, and it was found that 6 to 8 feet of beach was lost.
“We were able to show immediately the effect of the storm on beachheads and the erosion, the dune losses,” Tim Oliver, Horry County’s IT/GIS director, told Route Fifty in an interview.
Fast turnaround means speedier access to Federal Emergency Management Agency renourishment and reimbursement funding.
A little more than a two-hour drive south, the city of North Charleston saw around 300 damage assessment points, two homes destroyed, flooded streets full of debris, and downed trees and power lines resulting from the hurricane.
“The big deal is getting FEMA to give their assistance,” said Kathleen Brenkert, the city’s GIS manager, said in an interview. “We have to be able to show we actually had damage, and the quicker we do that, the quicker we can get help.”
Inspectors didn’t need much training to perform damage assessments with Collector on their tablets to upload pictures and citizen information like homeowners insurance and contact numbers. A GeoForm was employed for “windshield assessments” field workers could do from the comfort of their vehicles.
Residents were also provided an online Citizen Report for alerting the city to damage, and about 230 logged in. Officials had already mapped areas of anticipated impact but then could compare it to areas of actual impact.
“We were aware of where some of the damage was, but this gave us a good idea of stuff we didn’t know about,” Brenkert said.
For instance, the portion of the city that falls within Dorchester County is a generally well-insured area that doesn’t call in with damage reports too often, and the Citizen Report filled in gaps in official knowledge.
As a result of ArcGIS, most damage assessment points were collected and mapped within two days of the storm, Brenkert said.
During the hurricane, City Hall lost power in the middle of the night, and the generator didn’t kick in—taking all network switches down. Servers couldn’t be accessed, so Brenkert quickly hosted the disaster response system in Amazon’s cloud.
Within 15 minutes, North Charleston’s recovery team was working again.
Damage data gathered by the city will later be used to obtain funding for flood studies to help with local drainage, and first responders will be trained to use ArcGIS in the future for faster reporting.
The region experienced a King Tide, an especially high increase in water levels, causing historic flooding that hadn’t been seen since 1928.
Using the county drone, damage assessments were performed on parcels before recovery teams could even get inside closed off neighborhoods.
The county will eventually fly over all critical buildings and supply 3D models to first responders for future emergencies.
“Drone imagery is higher quality than a helicopter’s,” Oliver said. “At the last count, we’ve seen over $20 million in damages, and that was before the flooding event.”