An estimated 6.9 trillion gallons of rain fell on Louisiana between Aug. 8-14. In less than one week, 31.30 inches fell. This was a rain event of Biblical proportions, and it caused massive suffering and destruction.
Our first response, of course, is humanitarian. Many New Orleanians were on their way north and west last weekend, bringing food, tearing out soggy Sheetrock, mudding out living rooms.
Once the situation has stabilized somewhat, we need to do more than respond: We need to think ahead. Chances are, this will happen again. We must think about how we can learn to live with water, even at this scale of inundation. We can’t avoid the rain, but we can prevent the flood.
Let’s not let this crisis go to waste. Let’s think hard about how we can make the interconnected system of urban development, infrastructure, and nature work for us in a way that allows the water to dissipate as quickly as it pours down on us.
Consider this: A live oak or bald cypress tree drinks up to 1,000 gallons of water per day, transpiring it back into the air. These are beautiful, native, water-loving trees that thrive for hundreds of years in our semitropical climate. Anyone who has had one in their backyard knows how quickly they can absorb tremendous amounts of water. One million of these trees — about as many as SOUL estimates New Orleans needs — can soak up 1 billion gallons per day. This would help.
Much of New Orleans used to be swamp. It was densely forested with abundant shade and enormous water absorption capacity. Incredibly, today it is the least- forested city in the United States. We can reverse this. It’s not just about floods, though. There are so many other benefits — trees lower the temperature, they create oxygen, they make our streets and neighborhoods inviting, beautiful and even safer.
Rural Louisiana suffers from deforestation as well, largely due to development of subdivisions and commercial areas that raze the forest and level the land before construction. Many times, subdivisions are built right to the river’s or swamp’s edge, without a buffer that can absorb runoff. Gigantic shopping mall parking lots, paved with impermeable asphalt, inundate their neighbors with runoff. We may need subdivisions and shopping malls, but there is a whole world of design knowledge about how to construct them to work in harmony with nature, not against it. Let’s use that knowledge.
And then there is the issue of infrastructure. We need to respect the gravity of gravity. Water always travels downhill, and it needs to have an unobstructed path to the huge part of Louisiana (19,000 square miles!) that consists of floodplains, creeks, and basins. Our state is naturally designed to absorb water — let’s make use of it!
Roads are one problem — if they are badly designed, they turn into dams during heavy rains, causing massive flooding. We can fix that. There is so much we can do in cities, too, such as grading streets to drain into sidewalk detention areas, or using permeable surfaces to allow water to seep into the earth, thus stopping the subsidence of our neighborhoods. Everything we build can be designed with water in mind.
Fundamentally, we need to seriously rethink our baseline assumptions for new development. Katrina was a 100-year event. The recent floods were 1,000-year events, and it sure seems like these “rare” events are not so rare at all. Are there really good reasons why new residential and commercial developments should not be designed to withstand a 1,000-year flood, or a 2,000-year flood? And why should new development be allowed to increase stormwater runoff, without also creating the means to absorb it? Does this make sense?
All of the above concepts are pretty simple. But they involve all of us “thinking with water,” from the citizen level to the Governor’s Mansion. If we all get on the same page and implement these changes collectively, we can continue living in this beautiful gumbo of a place we choose to call home.
Susannah Burley is director of Sustaining Our Urban Landscape (SOUL), an NGO dedicated to reforesting New Orleans. SOUL is a project of The Trust for Conservation Innovation. She can be reached at email@example.com, or www.soulnola.org. Andreas Merkl chairs the SOUL Advisory Committee. He is a resident of New Orleans. He also spends time in Washington, D.C., as CEO of Ocean Conservancy, a national NGO with offices across the Gulf of Mexico region.