Association of State Wetland Managers - Protecting the Nation's Wetlands.

Counting Cattails: What’s Wetland-Loss Got to do with it?

final one againBy Melissa Mullineaux, Summer Intern, ASWM

As many of you may know, Louisiana is currently in a state of emergency according to Louisiana Governor John Bel Edwards, due to recent torrential rainfall and flash flooding in the Baton Rouge area. The federal government is declaring it a major disaster and, at the time I am writing this, 40,000 businesses and homes have been flooded, at least eleven people have lost their lives, 30,000 people have been rescued, and 40,000 have registered with FEMA for disaster assistance.

These floods have been deemed record breaking as, according to Climate Nexus, during this storm nine river gauges read record high levels. In fact, rivers in Baton Rouge remain above flood stage levels and Gov. Edwards is declaring it a “truly historic event.” That is because Baton Rouge saw double the amount of rainfall in a 24-hour span of time than it would see, generally, the entire month of August. For example, CNN reports that “one river, the Tickfaw, rose 20 feet in 14 hours, breaking a previous crest record by more than three feet.” Wow! This flood is unprecedented! I can’t help but keep wondering, though, if this disaster has been exacerbated by wetland loss.

flood2In my last blog post, Where Have all the Wetlands Gone?, I talked about wetland loss throughout the years in the United States. And, in the spirit of keeping the pattern going, it only seems fitting for my second blog to talk about this tremendous flood in Baton Rouge in relation to wetland loss in Louisiana.

So, what does wetland loss have to do with it, anyway? A wetland, as you probably know, is like a giant natural sponge that soaks up excess flood water through its abundance of live plants, roots and vegetation and also through its decaying plant matter. This process also slows down the flow of flood water and helps distribute it back into the floodplain more gradually. The combination of storing excess water and releasing it more gradually work together in not only lowering flood heights but reducing damaging erosion. In turn, this helps keep homes and businesses safe from floods!

wetland081816As I mentioned in my last blog, over 50% of our nation’s wetlands have been destroyed by being filled, dredged or drained to use for some other purpose. That means that many of them are no longer there to assist with keeping businesses and homes safe from flooding. That seems very scary to me.

I recently read a surprising statistic on EPA’s website that says “the bottomland hardwood- riparian wetlands along the Mississippi River once stored at least 60 days of floodwater. Now they store only 12 days because most have been filled or drained.” If all of Louisiana’s wetlands were still intact would this rainstorm have been as damaging as it was to the affected communities? Eric Holthaus (2016) states that this storm is considered a “500-year rainstorm,” meaning “a downpour with an estimated likelihood of just once every 500 years, and roughly three months’ worth of rainfall during a typical hurricane season.” At least the wetlands, if they were still around, might have held a portion of the water and might have lessened some of the damage. However, even a sponge can get so filled with water, it can’t absorb any more. Also the size and location of the sponge (i.e. wetland) determines whether it will absorb floodwater that would otherwise reach a community. At best the presence of wetlands can only be part of a solution to avoiding flood losses.  But they can be an important part and have the potential of become more important in the future.

While researching this terrible disaster, I have been coming up upon articles that are making connections between the record breaking rainfall and climate change. This is interesting to me because some climate observers are calling this “500-year rainstorm” a “classic signal of climate change.” Their reasoning behind this statement is based on research that states that warmer climate temperatures enable the atmosphere to hold more water vapor (“about 7% [more] per 1°C warming”) and global warming is producing warmer temperatures. Furthermore, Trenberth (2005) makes the argument that “storms, whether individual thunderstorms, extratropical rain or snow storms, or tropical cyclones and hurricanes, supplied by increased moisture, produce more intense precipitation events that are widely observed to be occurring, even in places where total precipitation is decreasing. In turn, this increases the risk of flooding.” This information is something for communities to think about, as storms increase and weather becomes more extreme, a trend we are seeing more of these days. Finding ways to absorb floodwaters through wetlands and other nature-based methods can be one of many cost effective approaches to reducing flood risk.

As for the folks in Louisiana and other states where this flood has caused havoc, my thoughts are with them. I know many are displaced from their homes and are suffering grief and loss. Healing and rebuilding will follow, but these things take time. I know I have learned some valuable lessons about the importance of wetlands and our natural environment through this process and stay tuned for some more blogs from Counting Cattails so that you may follow me in my journey as an intern here at ASWM.

Here is a link to a YouTube video that shows aerial drone footage of the Louisiana flood of 2016:

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One Response to Counting Cattails: What’s Wetland-Loss Got to do with it?

  1. Scott Yaich says:

    For more on this topic, check out a series of papers by S.D. Brody and colleagues that assess the connection between wetland loss (and other factors) and insurance payouts in the Gulf Coast states.

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