Daniel Champton didn't buy flood insurance for his home in the Ascension Parish town of Galvez. Based on federal flood maps, he wasn't required to.

In August, he became one of the tens of thousands of south Louisianians living outside of federally designated high-risk flood zones whose houses took water.

Yet Federal Emergency Management Agency officials — tasked with not only responding to those victimized by floods but also with helping prevent the damage to begin with — have made it clear over the past month they won't revisit the accuracy of those maps.

Even more recently, officials doubled down on that promise, saying that not only would the flood maps stay the same, the widespread devastation won't prompt increases in flood insurance premiums. The reason is simple, FEMA officials have said: The rain that brought on the flood was so unprecedented it won't force a re-examination.

Leaders in the hard-hit Baton Rouge area have welcomed FEMA's assurances as needed continuity for their constituents. 

But some researchers and critics of the flood-map process are raising questions about that approach, saying the scale of the flooding is actually a reason to take another look at the maps. They argue that inspection should not only reflect on the conclusions the maps come to but dig deep into the way they are developed and how construction throughout the region over the past couple of decades has altered drainage.

Craig Colten, an LSU historical geography professor, urges revising the maps. He noted the August flood was Louisiana's second major flood caused by rain in 2016. Severe rain in March brought high water to Livingston and Tangipahoa parishes and elsewhere. But he said he understands why people might be glad to hear FEMA doesn't plan to change the maps, which could lead to higher insurance costs or even pricey elevation of homes.

"I'm always sympathetic. If my house was out there and been flooded, I'd be in the same boat, and I would be basically facing extraordinary expenses, but I think in the long run, what's really unfair is to force these people who've suffered damage to face the risk again and face the peril that that they'd have to rebuild again," said Colten, who has written about Louisiana's efforts to tame its swamps and coastal environment. "Which is more expensive? Raising a house now or relocating now, which might be a big financial burden, but if they have to do this again in five or 10 years, it's an even bigger burden, to say nothing of the emotional cost."

Bigger storms?

Meanwhile, nationally, experts are rethinking the FEMA maps relied on by the National Flood Insurance Program. Some see the current map methods as out-of-date, painting with too broad of brush that, in combination with local building rules, fails to adequately convey the risk of flooding to property owners.

Sally Ann McConkey, who coordinates hazard assessment and mapping for the Illinois State Water Survey and has advised FEMA on updating its maps, said the flood maps are designed for a bigger picture purpose than what's needed for local growth planning. They're created to manage the financial risk for national flood insurance and don't provide the kind of safety standard that the public or even local government officials might expect, she said.

The threshold used by FEMA on those maps is the 100-year flood. Where such a disaster is likely to strike drives who must have flood insurance if they have a mortgage on a property.

Despite the name, the 100-year flood is statement of probability — a flood that has a one-in-a-hundred chance of happening in a given year, though also a more than one-in-four chance of happening over the life of a 30-year mortgage.

Further, the models behind the FEMA maps don't take into account additional levels of uncertainty from the growing effects of incremental sea level rise and the prospect of even more severe increases due to global climate change, floodplain experts say.

Chad Berginnis, executive director for the Association of State Floodplain Managers and a former Ohio hazard mitigation officer, said the nation's flood modeling, which relies on statistics from years of past rainfall and flooding, has the built-in assumption that the future will be the same as the past. But floodplain managers across the nation are seeing that storms are increasingly more intense than the statistical data used to create flood maps had predicted, he said.

"We are seeing change in our atmospheric events, and so what does that mean for the future?" Berginnis asked. 

Flood maps also might not adequately reflect changes in drainage because of construction. McConkey said FEMA chronically has lacked the funding to consistently update flood maps to account for new development and other changes. She suggested the best solution to avoid future flooding is to tightly control and limit development in the 100-year floodplain.

"That's really the key, is to get of out high risk areas because the rains are going to come. You can't build enough reservoirs; you can't build enough levees," McConkey said.

East Baton Rouge, Ascension and Livingston parishes all have flood maps that are 9 years old or newer, but important studies of the hydrology that underlie those maps mostly date from 2005, before periods of strong home construction in the parishes.

However, Shannon Dupont, East Baton Rouge's floodplain manager, said he believes with the flood mitigation the city-parish has long required on new development, the map is still current. FEMA also updated parts of the parish map in 2012.

Elevation requirements

FEMA maps define the breadth and depth of a 100-year flood, designating the area that would be affected as a "floodplain" that is at highest risk of inundation. Researchers create the maps by combing through historical river and rainfall data, using airborne laser surveying equipment and tapping other information. When interpreted by local building codes, the 100-year-floodplain sets the mark for how high new properties must be built at a minimum, also known as the "base flood elevation."

In most of East Baton Rouge and Ascension parishes, new structures and subdivisions generally must be built 1 foot above the 100-year flood elevation determined by FEMA. In Livingston Parish, they must be built at or above that elevation.

Local officials around Baton Rouge said any bid to remap based on the August flood could deal a death blow to their communities. The governments of East Baton Rouge and Ascension parishes, as well as the city of Central, actually took steps post-flood to ease elevation regulations, which in some cases had previously been set higher than federal minimum requirements.

The exact toll of the flood across south Louisiana is still being tallied, but state officials estimate waters swamped 150,000 homes and businesses in at least 25 parishes. Thousands of homeowners are now awaiting damage assessments that will determine if they have to bear the added expense of elevating their homes, in addition to the repairs. Those within the 100-year floodplain that incurred damage adding up to 50 percent or more of the value of the home might have to elevate, depending on how high the structure is already raised. 

"If they were to take this flood event that was so much of an anomaly and change the base flood elevation, you decimate the city, and folks are going to want to leave this city," Central Mayor Jr. Shelton said.

FEMA says it ultimately will use the data from this flood for regular map revisions, but the agency does not typically change the maps after one major flood. And, in any event, the process of making the map changes probably wouldn't be finished soon enough to affect rebuilding, local officials say.

But the idea of quickly putting in new elevation standards after a major event is not without precedent. After Huricane Katrina in 2005, FEMA established advisory elevation standards for New Orleans when the levee failures called into question what a safe elevation would be in the future. Communities had to adopt the advisory elevations to get access to money through the Road Home, the state rebuilding program funded by federal dollars.

Some have speculated that the Augst storm wasn't just a 100-year flood but in fact a 1,000-year flood — an event that has a 0.1 percent chance of happening in a given year and is 10 times less likely than FEMA's benchmark.

Local officials point to that fact, and the record-breaking river levels, to suggest the flood shouldn't prompt map changes.

"This thing that we just experienced in this parish, by any stretch of the imagination, whether you ask any meteorologist that's an expert on this type of an event, is exceedingly rare," Metro Councilman Trae Welch said. "To the point to where — I don’t know where the 1,000-year number came from, but we don’t base base-flood elevations on 1,000-year events and we shouldn't base base-flood elevations on 1,000-year events."

FEMA officials themselves have said part of the reason they aren't remapping is the enormous scale of the flood.

“All we administer to is the 100-year. So there are not going to be any advisory base flood elevations or map changes,” Mark Lujan, FEMA’s top mitigation expert for the South, told Sorrento residents in a meeting last month.

While the recent flood was a big one, it may not hit that 1,000-year mark. Climatologists have documented that a 1,000-year rain occurred in several places hit by the flooding. But soil conditions and other factors can affect runoff, making the official "size" of the flood less than the rain storm.

Todd Baumann, data chief for the United States Geological Survey in Baton Rouge, said recently that his agency has not yet determined the extent of the flood, but early data showed flooding was "routinely higher than a 1 percent event and, in multiple locations, approaching the 0.2 percent (500-year) range."

Insufficient data

Put down in various shades and tied to an entire architecture of local building regulations, FEMA flood maps have an air of certainty to them. Like road maps, they are marked with lines, abbreviations and numbers, showing where and how high the 100-year flood will reach with an implied level of precision that filters down to local building rules.

But Bob Jacobsen, a consulting environmental engineer and hydrologist for the Amite River Basin Commission, argues that the maps, while they achieve what Congress has mandated, don't paint an accurate enough picture of how flooding happens in the basin. Instead, federal, local and state officials should come together to devise better models, he said.

One problem with the maps is they are based on a limited historical record, even though it can take several hundred years worth of data to establish the true extent of a 100-year flood, Jacobsen said.

With that range of uncertainty, the flood height at the Denham Springs gauge on the Amite River for a 100-year event could vary by plus or minus 4 feet, Jacobsen estimated. The gauge saw its record height exceeded by 4.7 feet last month, still falling within the 100-year flood range that Jacobsen believes exists.

A written statement from FEMA did not dispute Jacobsen's assertions but did say the agency works with local officials to improve the maps' accuracy, continually evaluates the maps in light of new data and scientific methods, and strives to improve communication of the maps' findings to the public.  

Insurance implications

Roy Wright, FEMA deputy associate administrator for insurance and mitigation, told a Congressional committee earlier this month that flood insurance claims filed over the August floods in Louisiana already had totaled 29,000, making it the fourth biggest storm since the creation of the program.

Only Katrina in 2005, Hurricane Sandy in 2012 and Hurricane Ike in 2005 were higher, he said.

While exact numbers are still uncertain, preliminary data suggests the flood touched thousands of homes in the Baton Rouge region outside the zones FEMA designated as at high risk of flooding — the areas where mortgage holders must have flood insurance. 

For years, federal officials, joined by local and state leaders across Louisiana, have urged people to buy flood insurance whether they live in a high-risk zone or not.

But Jacobsen and Wright agreed that by using hard thresholds like the 100-year flood, the insurance program often creates a binary choice with the homeowners: In the plain, you need insurance; out of it, you don't.

Champton, the homeowner in Galvez, got 6 inches of water. Unknown to him, more than half of the lots in the Twelve Oaks of Galvez subdivision, including his, had been in the 100-year floodplain at the early stages of development a decade ago and would have been required to have flood insurance. 

But, under parish rules, dirt had to be added to raise those lots above the floodplain before they could be sold, said developer Michael Boies. The lots were built up 2.4 to 3.6 inches above the projected level of inundation from a 100-year flood, according to FEMA map amendments. 

Boies then was able to get the flood map amended under a legal process through FEMA to exclude those lots from insurance requirements. 

Champton said he wasn't told about the map change when he bought his house. But the St. Amant native also said he never would have thought the Galvez area was vulnerable. "I never ever considered flooding until ... right after we flooded," he said.

In October, a committee that reviews FEMA's flood mapping procedures recommended the agency move away from the 100-year-flood threshold for insurance rating purposes. Instead of looking at swaths of homes, individual structures would be examined.

But Wright said that while he agrees with the goal, it's a “transformative” leap that will require lots of new data, major changes in what FEMA does for insurance underwriting and revamping local development rules.

“It will take us years to get there, and it’s not exactly clear what we’re moving toward,” Wright said.

Meanwhile, local officials who oppose map changes, like Central's Mayor Shelton, said this flood offers a succinct lesson: Buy flood insurance.

“If you’re somebody who flooded, I don’t care if it’s the first time your house flooded, if you see that possibility and don’t do something to minimize that issue, then shame on you,” Shelton said.

Follow David J. Mitchell on Twitter, @NewsieDave.