In at-risk riparian areas of northern New Jersey, surveyors are using drones as part of the documentation for a Federal Emergency Management Agency (FEMA) program that saves Pompton Lakes residents hundreds of thousands of dollars per year on flood insurance premiums.
Land-use consultancy Dresdner Robin of Jersey City, N.J., recently worked with the Borough of Pompton Lakes, N.J., using unmanned aerial vehicles (UAVs) to gather overlapping photographs of three rivers in the borough.
Greg Gloor, survey director at the firm, volunteered on a project to assess Pompton Lakes’ flood-prone waterways. Gloor flew 11 individual flights over the rivers at 215 feet above the water level. The UAV moved at 10 mph, using a 15-millimeter, fixed-zoom lens, capturing 60-foot sections of the terrain. Images were snapped every two seconds (1,042 total) and were later analyzed to locate obstructions in the river channel. The photos aided a stream-cleaning project that is part of the borough’s flood mitigation program, says the firm.
The UAV-collected data was also submitted as part of Pompton Lakes’ application to FEMA’s Community Rating System (CRS) program. Waterway assessment is a key component of the CRS program, and active participation saves the borough’s residents over $300,000 on flood insurance premiums, according to Dresdner Robin. Outside of cost benefits, the UAV program also saved the borough’s volunteers hundreds of hours of firsthand analysis time, according to Pompton Lakes’ councilman, Erik DeLine.
He says that the drones “produced stunningly clear imagery, which enabled us to fully understand and prioritize which hazards needed to be cleared, providing an invaluable service to our residents.”
On the project, Gloor notes, “Assisting a borough that houses three rivers – which can pose a threat to homes and other structures – is rewarding. Historically, the flood threat can be quite active here, but this emerging technology helps mitigate it.”
He adds that the image-capture project offers a feasible way to spot obstructions, and the visuals help facilitate FEMA’s CRS program, spurring immediate financial benefits.
According to Dresdner Robin, Gloor’s work has helped expand similar waterway assessments in New Jersey, including the Ramapo River in Oakland. There, both video and still photography – including for the adjacent tributaries – are used to assess river conditions for restorative work with the state.
As flooding continues to plague areas of northern New Jersey, especially following a particularly wet 2018, surveyors anticipate the need for survey and data acquisition of river corridors to rise, the firm says.
Unlike traditional surveying or photogrammetric surveying performed with a pole-mounted camera, UAV surveys can be performed without interfering with traffic flow or placing surveyors close to dangerous conditions near rivers and roadways, the firm points out.