NICK GOSNELL
Hutch Post
HUTCHINSON, Kan. — At the request of Reno County Commissioner Don Bogner, County Planner Mark Vonachen explained the process of how floodplain maps are determined for the county after one of Bogner's constituents asked.
"The floodplain is through FEMA (Federal Emergency Management Agency), Vonachen said. "FEMA contracts with the state, the state, in turn, contracts with various engineers throughout the region to analyze and develop the floodplain maps. As far as why they would change? Part of that would be development. When you develop in a floodplain, when you bring fill in, when you construct houses, then you're changing the floodplain dynamics out there. That's one reason why the maps can change over the time. The second reason they could really change is through better technology."
Vonachen explained that they have upgraded technology in recent decades from dot matrix maps all the way to the latest and greatest, which is Lidar technology.
According to the NOAA, lidar, which stands for Light Detection and Ranging, is a remote sensing method that uses light in the form of a pulsed laser to measure ranges (variable distances) to the Earth. 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. A lidar instrument principally consists of a laser, a scanner, and a specialized GPS receiver.
"The goal, always, of floodplain maps, is to provide the best and accurate maps, where people can understand what that floodplain is," Vonachen said. "Not just based off of a computer drawing, or somebody's recollection of the area. We base it off of now, lidar, the majority of the county right now is under review for a revision to the floodplain maps. You'll recall, in 2021, we adopted new floodplain maps, mainly because of the levee certification for the city of Hutchinson. We did the Cow Creek watershed area north of town. That map was recently adopted. There is a project underway to finish the county and base it off of lidar."
Vonachen doesn't know when that will be done, as FEMA, and therefore, the downstream agencies, are behind on that work. However, once it is done, the county is obligated to approve those maps, in order to retain eligibility in the National Flood Insurance Program.
"The map needs to be adopted by the governing body, in order for citizens to be able to purchase flood insurance," Vonachen said. "Without adoption of the map, then nobody can purchase flood insurance, and existing policies that are in place, once they are up for renewal, those would expire and not be able to be renewed."
It also could have an effect on disaster funding in the case of a flood, as well. Most of the county's floodplain maps, with the exception of the portion approved in 2021, date back to around 2010, so it's time to work on them again.