New floodplain maps in the works for Ozark County

Missouri’s State Emergency Management Agency (SEMA) has begun the process of updating outdated floodplain maps to better reflect flood hazards in the state, including those in Ozark County.

SEMA personnel and a representative of Wood, the mapping contractor company, met Dec. 24 in Gainesville to share information with local officials and other stakeholders. “It was a helpful meeting. There are gonna be some areas that change,” said Western Ozark County Commissioner Greg Donley after the meeting. 

“A lot of houses will come out of the floodplain,” said Ozark County Emergency Manager Curtis Ledbetter, who also attended the meeting. 

Due to new mapping technology, those attending the meeting discussed the likelihood that some properties that fall within the flood zone on the current maps will no longer be within a flood zone, while other properties will likely be added to the mapped flood zones. This change could affect flood insurance requirements for those landowners. 

Gainesville and the village of Theodosia participate in the National Flood Insurance Program, which means anyone in those communities can purchase flood insurance through NFIP, but the rest of Ozark County does not participate in the program.

“Residents whose houses are in the floodplain and have a federally backed mortgage are required to purchase flood insurance. The new maps should define the extent of the floodplains much more accurately than the previous 2007 rendition by using new topography data and applying new two-dimensional flow analysis processes,” SEMA Floodplain Engineer Section manager Darryl Rockfield told the Times.

A system called LiDAR (light detection and ranging) is one of the new technologies that will help improve the accuracy of the floodplain maps. At the meeting, presenters explained how LiDAR data is collected via a transmitter that emits laser pulses that reflect off of a surface then return to the LiDAR sensor on an “airborne platform.” According to the National Oceanic and Atmospheric Administration, these light pulses—combined with other data recorded by the airborne system— generate precise, three-dimensional information about the shape of the Earth and its surface characteristics.

“The LiDAR data was collected during the 2018 flight season. This data should encompass any stream-altering that occurred during the 2017 flooding event. Surveying in Ozark County for detailed study miles will likely occur in late January/early February of 2020,” said Rockfield.

After information on the ground topography is collected, a study of the area’s hydrology will determine how much water from a given rainfall makes it to the creek, stream or river. Then, a hydraulic study determines how high and wide the water will get after reaching the stream. The height of the water surface is determined by the slope of the ground, presence of plants and trees – which slow the water and make it go higher – how confined the channel is, and infrastructure such as roads.

“I thought it was a very good meeting, and I think it’s going to turn out the way I was hoping, in the end,” said Tecumseh resident Joe Corbin, who has been an active proponent of making FEMA’s flood maps more accessible to local residents who may be at risk. Corbin said the new maps will be online as well as in printed scroll form, which will be available free upon request.

Drafts of the new maps will be available for the local community to review in about nine months, but it could take three to four years for the maps to be completed and ready for official use, he said.

Draft data of the new maps will be available at http://bit.ly.MOSEMAOutreach. To view current FEMA flood maps (created in 2007) visit: https://msc.fema.gov/portal/home and enter a location.