Sept. 2, 2016 10:45 AM

Much of the flooded areas across South Louisiana share something in common — sprawl. But climate change connects it all.

Youngsville's Highland Ridge subdivision
Photo by Daniel Landry

To call the catastrophic flooding of August the Great Flood of 2016, or a 1,000-year flood or even a 200- year flood, seems desperate and delusional. Type “Great Flood of” into Google and the drop-down will offer “2016,” “1993” and “1927.” Remind me what we called the rain four months ago that inundated the Sabine River at the Louisiana-Texas border, flooding communities and shutting down I-10 for nearly a week? These great floods seem to be getting routine. But their effects are often most pronounced where there is sprawl.

Consider two of the hardest-hit communities in August — Youngsville and Denham Springs. Each is a small town in proximity to a faster-growing urban area, and each once used to have enough of a rural buffer to maintain its small-town character. As those urban areas, Lafayette and Baton Rouge, respectively, underwent the typical transformation of the

20th century — white flight to the suburbs and the residential and commercial development to accommodate it — Youngsville and Denham Springs became less small town and more bedroom community. Today it’s hard to tell where Lafayette and Baton Rouge end and Youngsville and Denham Springs begin.

Denham Springs (population 10,215 at the 2010 Census) and Youngsville (11,961) grew rapidly over the last decade, and the agriculture and woodlands that surrounded them and served as a sponge during highrain events were paved over and replaced with cookie-cutter subdivisions. A hydrologist quoted recently in The Daily Advertiser referred to it as “pavementization” — roads, parking lots, driveways and buildings replacing woodlands and farmland, leaving rainwater with dwindling means of retreat.

Yet it wasn’t just bedroom communities born of sprawl that flooded. Lafayette neighborhoods that had never taken on water were inundated, and there’s likely little we could have done in the recent past to prevent it. As Lafayette, like communities across South Louisiana, grew over the 20th century, we adopted a drainage model that promoted cementing in natural drainage coulees to get rainwater to the closet bayou or river as quickly as possible, in our case the Vermilion. Historically it worked, but there was simply no way that modest waterway could have digested the nearly 20 inches of water the Lafayette area received in a matter of days, causing the coulees that feed it to overflow. According to estimates, the no-name storm in August dumped three times as much rain on parts of Louisiana as Hurricane Katrina — 7.1 trillion gallons, or enough water to fill Lake Ponchartrain four times. It boggles the imagination.

A former member of Lafayette’s Planning Commission tells me that city-parish government has more recently placed an emphasis on retention ponds for commercial and residential development — on keeping water in place rather than directing it immediately to the Vermilion. But that’s been a recent emphasis, and the catastrophic rain in August was simply too much for our lagging infrastructure to manage.

Regardless of whether you accept what an overwhelming majority of climate scientists have come to believe based on the evidence — that human activity is having an adverse affect on the climate — there’s no argument that the climate is changing and that these “extraordinary” weather events are likely to become rather ordinary.

NASA reported at the end of August that Earth is warming at a pace without precedent in the last 1,000 years, with the last 30 years proving to be “exceptional territory,” according to the director of NASA’s Goddard Institute. Whether our smoke stacks and SUVs are causing it might be debatable among politicians — it’s not among climate scientists — but it’s happening, and the next “Great Flood” won’t be in another 200 years. How and where we develop, and how we mitigate such phenomena with future infrastructure will say much about our willingness now to live in an evidence-based reality that will serve us in the future.

Email Walter Pierce at walterp@theind.com

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