NASHVILLE (AP) - Thousands of property owners may have to purchase flood insurance for the first time as new flood maps go into effect next year in Davidson County.

The Federal Emergency Management Agency last month finalized revised flood maps for the county, and more than 4,400 properties were added to high-risk zones, The Tennessean reported (http://tnne.ws/2fRUYDT) Sunday.

Since the last update in 2001, engineers flew laser instruments over more areas of the county, improving topographic base maps, Metro Water Services Assistant Director of Stormwater Tom Palko said. That allowed more accurate flood modeling. Land not previously studied in detail was also surveyed.

"The intent of the flood maps is to identify risk," Palko said. "If an area was previously unstudied, then we did not know the risk associated with living or building in that area."

Mortgage companies typically require coverag e if a property falls into the 100-year flood plain - an area with a 1 percent chance of being inundated each year.

Homeowners whose properties fall into the flood plain may be eligible for subsidized policies through the National Flood Insurance Program. But they have to sign up before the maps become effective in April.

According to federal officials, an average flood insurance premium costs about $700 per year. Homeowners first have to survey their properties and calculate their flooding risk to determine the exact premium.