New flood maps show more of Alachua County at risk

Jul. 4--For prospective home buyers, mapping that determines the likelihood of a piece of property to flood can make or break a deal -- flood insurance required for property in a flood zone is expensive, while most other polices don't cover flooding at all.

Homeowners and local governments have relied on mapping by the Federal Emergency Management Agency -- FEMA -- to determine the risk of flooding for any particular parcel of land.

But new flood mapping by a nonprofit is available, and it shows that Alachua County has slightly more homes at risk than the FEMA maps.

First Street Foundation, a research and technology group, has developed mapping to better define areas that are prone to flooding and predict flooding at intervals for the next 30 years.

The importance of accurate mapping is evident throughout the county -- think of the inundation of Meadowbrook, Hills of Santa Fe and Robin Lane, among other subdivisions, when tropical storms sweep through.

Lalit Lalwani, a civil engineer and head of Alachua County's development review department, knows the issue thoroughly, including the history of the flooded neighborhoods.

"They were built in the 1970s, and the regulations and the modeling done at the time was a lower model than what we have today," Lalwani said. "Nowadays, those neighborhoods would have different regulations if they were developed today."

New developments, for instance, are required to build stormwater retention basins that can result in modifications to FEMA maps if approved by the county and by FEMA.

The county can also require that new homes in flood zones be elevated.

In 2006, FEMA revised its flood maps for Alachua County, adding 3,000 more properties to flood zones. Residents flooded County Commission meetings to protest, with many contending their homes were high and dry.

FEMA data indicates that 6.3% of parcels in the county have a 1% percent chance of flooding in any year -- commonly referred to as a 100-year flood. Flooding is defined by FEMA as water getting into the footprint of a house.

But First Street, which developed its models with assistance from researchers from several universities, contends that 8.4% of parcels are at risk.

That number rises to 8.9% by 2035 and 9.4% by 2050.

Two primary reasons exist in general for differences between First Street and FEMA, said Jeremy Porter, First Street's director of research and development.

"FEMA maps are highly politicized. There is a lot of community buy-in that has to take place and there are a lot of restrictions placed on FEMA. They are handcuffed in ways that a nonprofit like ourselves are not," Porter said. "There are technological differences. We map a lot of smaller streams, tributaries and smaller rivers that FEMA doesn't map. And we map rainfall ... and allow the elevation to tell us where the rainfall is going to go."

First Street modeling indicates that FEMA overestimated the number of flood-prone parcels in some North Central Florida counties, perhaps forcing owners into unnecessary flood insurance.

For instance, Bradford County has 19.5% in FEMA flood zones while First Street puts the calculation at 7.1%.

That discrepancy exists because FEMA sometimes puts wide swaths of land in its flood zones while First Street's is more precise, Porter said.

Gainesville Realtor Betsy Pepine said prospective home buyers must be told if the property is in a flood zone under Florida law.

Some buyers will reject a house outright if it is in a flood zone. Others are not bothered by it.

In Alachua County, the designation typically adds $500 to $1,200 to the cost of insurance, depending on the size of the home and other factors, Pepine said.

"Definitely it is a big deal. From my experience it will decrease the value by 10%," Pepine said. "You have buyers who will rule it out immediately because they are scared of it and not familiar with it, or they lived through major storms and have had floods."

Because the buyer pool for a home in a flood zone is small, a true market dynamic does not come into play. That reduces the value of the home, Pepine said.

First Street uses historical flood data, high-definition imaging, satellite flood imaging, high resolution elevation data and other technology to develop its flood models.

The difference between FEMA and First Street is fairly modest for Alachua County but more substantial for other counties.

In Levy County, where parts of downtown Cedar Key often flood at certain high tides, FEMA has 15.9% of property at risk of flooding. First Street has it at 22.5% and rising to 27.7% by 2050.

The University of Florida has done modeling in Cedar Key to help forecast what the city will face with sea level rise so it can begin to adapt.

Among those involved in the project was Morris Hylton III, director of historic preservation for UF's College of Design, Construction and Planning.

Hylton said maps from the National Oceanic and Atmospheric Administration -- NOAA -- are more reliable than FEMA maps.

Shortly after UF did its modeling involving digital imaging and other technology, Hurricane Hermine blew through the region. UFs modeling on the impact of storms proved to be accurate, Hylton said.

Similar UF projects have been done in other historic coastal cities including St. Augustine.

"I don't know any expert who does coastal resilience who believes that FEMA's numbers are accurate," Hylton said. "NOAA's data tends to be, at least from my experience, what most municipalities are using for planning and adaptation resilience."

First Street's goal is not to compete with FEMA, but instead to offer property owners, local governments and others a new option for evaluating the current and future likelihood of flooding.

Matthew Eby, First Street founder and executive director, said the group is able to provide information for specific property that has not been available before from FEMA.

It also takes into account the potential impacts from climate change.

"All of our statistics are calculated for the singular property and on our website for that specific property rather than just being a zone," Eby said. "If you plan to own your home for 30 years, here's the flooding statistics for the 30-year period accounting for that changing environment so you know what to expect as a homeowner."

___

(c)2020 The Gainesville Sun, Fla.

Visit The Gainesville Sun, Fla. at www.gainesville.com

Distributed by Tribune Content Agency, LLC.