It’s sedimentary, my dear Watson
May 27, 2011 § 4 Comments
Calling your attention to an excellent op-ed in the Los Angeles Times this past week, Let the River Run – providing some historical context for the construction of dams on the Mississippi River that have contributed to the massive loss of coastal wetlands along the Louisiana coast (they lose approximately 25-30 square miles a year) and floodplain development – and therefore heightened flood risk, and background to the recent opening up of the Morganza spillway. The piece also gives space to an often unconsidered, forgotten, human dimension: the forcible relocation of Native Americans, in the middle of the 20th Century.
To those unfamiliar with the issue, dams trap sediment, but sediment builds and rebuilds river channels, floodplains, wetlands and coastlines – via flooding.
So dams interfere with this natural process, and we (the collective we, who have handed responsibility over to our Publics Works departments) are then stuck with the management problem of clearing dams and basins of sediment and all sorts of things to manage downstream effects. We need to make the connection: this story about the Mississippi and its management problems has information for us. Their trapping of sediment had downstream effects, our trapping of sediment has downstream effects. And in an emergency situation, flooding had to be brought back into the picture…meanwhile we in LA fight over whether or not to clear basins of sediment to prepare us for inevitable large storms.
What’s missing from our discussions is recognition of a San Gabriel Mountain-sized elephant in a corner of the room: the absence of a long-term sustainable solution, one that involves some measure of floodplain restoration, in-channel sediment transport. How much money have we sunk in diesel fuel alone over the decades to truck this stuff around, supplanting the free, emissions-less, work of gravity? And how much more are we willing to spend? How many more oak woodlands or canyons are we willing to fill with dirt that naturally washes downstream? How many times will we watch increasingly rare species colonize in debris basins only to be wrenched out to protect downstream humans? Some of the outrage and fighting over short-term management issues is a worthy reaction, a wake-up call to the fact that surprise! our rivers aren’t exactly healthy, but I believe that we need to refocus on that not-healthy-rivers bit, reach a little further in our scope, and recognize the beautiful simplicity of a gravity-based solution. That, yes, entails dealing with my favorite two words (after sediment and flooding, that is): political will.
Reading the L.A. Times, between this fine piece about a far-away river, and our local flood control dramas, such as the Devil’s Gate sediment removal, may make your head spin for the lack of consistency in perspective and understanding, insofar as the Times editorial staff is keeping a much narrower view of managing our waterways in the name of public safety. Would they ever acknowledge the value of floodplain restoration as a key to unlocking the sediment troubles at Devil’s Gate and beyond? Perhaps someone in Louisiana is writing an op-ed to that effect, albeit no doubt while grumbling about the Morganza spillway.
I suggest everyone who is concerned about fires, flooding, sedimentation,dams,levees,etc. read John McPhee’s “Control of Nature” for a better understanding of these issues. It’s complicated but if the San Gabriel Mts. are permanent and if vegetation, fires, floods sedimentation aren’t revoked, we have a long time problem that needs a long term solution. Perhaps 606 grads have a better understanding than most.
I like this phrase “gravity based solution”
That’s a phrase that’s worth using…
Hey Jessica, I like that you’re raising this issue and asking these questions. What’s your take on the recent NYT article regarding waterway restoration in Mexico City?
Daniel! Haven’t seen you guys in a long time! Hope you are well.
As a native angelena, I don’t actually read the NYT unless someone sends it to me with underlines and notes saying READ THIS! I’ll take your post as such and look up the piece, sounds interesting! Avenida Rio Churrubusco has its name for a reason, and one of my original inspirations for Seeking Streams was the efforts by Homero Arjidris in DF to map and restore the old lakes of the city. And since I admitted this weakness of character(not reading NYT), I should add it’s not that I actively resist the NYT, but that I read the LA Times fairly faithfully out of habit, and will continue to root for the home team until it dissolves completely into advertisments and comics.