“What we're doing now is to be better prepared, using science to better prepare ourselves for that next flood,” said Justin Ehrenwerth, president and CEO of the nonprofit Water Institute.

In other words, it is a global water cooler to study water. The campus is home to the just-opened Water Institute of the Gulf, a striking structure that appears to hang over the edge of the river.

“A collaborative environment,” according to its website, where experts from around the world will be “studying coastal threats, formulating theories, exchanging ideas, and cooperating to arrive at innovative solutions that might never be possible working alone.”

Ironically, as the rain came down in Baton Rouge, a $60 million research center was going up, specifically to study water. The Water Campus covers 35 acres on the edge of the Mississippi River, adjacent to downtown Baton Rouge. The plan over the next decade is for it to employ more than 4,000 researchers and scientists in 1.6 million square feet of laboratories, research facilities and commercial space.

Rivers and creeks overflowed into each other within hours, flooding neighborhoods. More than 100,000 homes were inundated, some destroyed. The water caused nearly $4 billion in residential property damage alone, according to Louisiana Economic Development.

BATON ROUGE, La. — In August 2016, a massive rain storm stalled over Louisiana , dumping nearly 30 inches of rain across the Baton Rouge area.

The project grew out of the destruction from Hurricane Katrina. After that devastating 2005 storm, researchers from Louisiana traveled to the Netherlands to see how the Dutch were defending their coastline from rising water and increasingly severe storms.

“And they’ve developed remarkable structures and remarkable sciences," said Ehrenwerth.

It is also home to an applied research group, Deltares, which employs 850 people in 40 countries. The group from Louisiana was so impressed by the projects and by Deltares, they came back to Louisiana and built the Water Institute

“We look at every aspect of the coastal set of challenges, from the ecosystem, environmental stressors, to what it means for the people, the economies that are on the coast,” said Ehrenwerth. “There are ways to use the best available science to better prepare, to better respond, and to be able to get assets and people — out of harm's way.”

This is happening as Baton Rouge is in the midst of a building boom. The number of construction permits has nearly doubled in the last five years, according to the Downtown Development District.

John Davies is a local real estate developer and also CEO of Baton Rouge Area Foundation, which is working to fund the Water Campus.

“If we don't deal with the issue of water rise and the loss of land in South Louisiana, there will be no South Louisiana,” said Davies. He says the institute is already paying off, not just for Baton Rouge, but for communities, infrastructure and economies up and down the Mississippi.

“What we didn't realize would happen as a result of the floods is that, the Water Institute of the Gulf developed a methodology to be able to predict inland flooding.

And they have the sole model to do that in the country,” he added.

Next door to the Water Institute, another unique weapon in the battle with water, is a giant Mississippi River simulator, the centerpiece of the Louisiana State University Center for River Studies.

The $16 million laboratory is the size of two basketball courts and at first looks like a giant skating rink. It enables researchers to literally play with the river, pushing water and sediment in different directions to better understand the interplay between land and water. They can then test new levees and barriers to prepare for rising water.

“We harness the power of science to figure out how can we build structures, how can we build new wetlands and new barrier islands, that will help protect properties and infrastructure along the coast so that when the next storm comes, you've got buffer,” said Ehrenwerth.

Jeff Hebert was chief resilience officer of New Orleans before joining as vice president of the Water Institute, where he is helping to bridge the science and the tools that they develop there to help communities better adapt to changing environments. The 2016 floods provided him with an example, right outside the front door of the lab.

“The flooding that happened in Baton Rouge happened in areas that are more newly developed and basically areas that were built on what you would call the natural drainage system of a community,” said Hebert. “I do think that with Hurricane Harvey in Houston and all of the destruction you saw in Puerto Rico and the threats that Florida faced — near misses every time last summer. I think that really woke people up a lot, and you see more discussion about what can we do to prepare for what's happening today.”

Hebert said he believes most developers are paying attention to the science of rising water and extreme weather, but they have little incentive to invest in resilience.

“Because insurance is still covering it. You can still get insurance. You can still get financing to build the product,” he said.

But, he notes, investors, financial institutions that fund real estate projects, are paying more attention to the impacts of climate change on their portfolios.

“And I think over time you’ll start to see a transition, but I think for a very long period of time, you will continue to see investment in coastal areas,” added Hebert, who also points to redevelopment in Houston.

In May, the campus hosted its first international conference, drawing more than 200 experts from around the world.

“This science is taking place in Baton Rouge, and we are exporting it around this state, across the Gulf of Mexico, and all over the world,” said Ehrenwerth.

Much of the talk at the conference was about past experiences, floods in other cities and what city planners are still learning. There seemed to be no question that the dangers of rising water and increasingly extreme weather are only getting worse.

“We’re planning for a future event that is actually going on,” said Hebert.

That means not just rethinking how to rebuild, but reimagining how to live.

“We are preparing ourselves for the worst,” said Ehrenwerth.

-- CNBC's Erica Posse contributed to this report