Thursday, July 7, 2011

Bad Science on levees makes it into the paper

© 2011 Joshua Stark

Alas, having an advanced degree in a field doesn't always mean you are always right all the time.

Take this op-ed piece in yesterday's Sacramento Bee.  In it, a Dr. Lund from UC Davis, a man who is probably nearly a genius in his field, makes some very dubious claims about Central California's levees.  Sadly, here he refers to no studies nor historical evidence to prove his position.

The professor's claim is that we should remove trees from all "urban" levees, per a requirement by the US Army Corps of Engineers, even though doing so may have bad impacts to riparian habitat and recreational values.  He is concerned because trees may weaken levees, and hide burrows from workers checking them.

What does the professor use to support his claim?  The fact that other parts of the world - namely, China, Japan, & the Netherlands - remove trees from their levees.

That's it.

He offers no studies in this article that have shown these levees to be superior to California's.  He offers no examples of California levee failures (or any levee failures) due to trees.  He offers no support whatsoever for such an environmentally devastating act, for an act that will forever change habitats and recreation on our levees.

After some research, I found Dr. Lund's article as a blog post where he actually does cite references.  However, the references are largely skewed (most being from the Corps), or almost never support his position.  For example, this Power Point presentation lists trees and vegetation that are more or less problematic according to their research on European levees.  The list describes a host of bramble bushes - blackberries and such - as less problematic for levees.  However, I daresay that a burrow would be harder to find in a blackberry bramble than under a valley oak.

Another example, from the Ca. Dept. of Water Resources link he cites:  "... California asserts that the Corps’ strict enforcement of the ETL and PGL will adversely impact public safety."

An earlier report by the Sacramento Bee, about the lawsuit by environmental groups against the Corps for this horrid idea, did mention the science on levee failures:
"But it (the Corps) offers little scientific evidence for those conclusions (to remove trees).  A 2007 symposium hosted by the Sacramento Area Flood Control Agency (SAFCA) offered evidence for the opposing view: Tree roots may, in fact, strengthen levees by binding soils together."

I am no levee engineer.  However, a quick google search of images from the last major levee failure on the California Delta, at Jones Tract in 2004, are telling; do you see any trees?  Also, think back to times when you've noticed tree roots, perhaps sticking out of the side of a cut-bank on a road or a creek.  Think about the dirt and rocks sticking to it, and how it and the land touching it stick way out from the eroded places around it, places that only had short grasses growing on it.

Last, I want to make a point about Dr. Lund's tone (and nearly everybody else talking publicly) when talking about levees:  It is super-easy to make dire predictions, because nobody wants to have been the Pollyanna the day one fails, and because the old saw about there being two types of levees (those that have failed, and those that are about to) is true.  But I would like to point out that this year we have experienced well over double our average runoff, and have had no major levee breech. 

It may be time to reconsider a push for drastic actions to redesign a system that has been working pretty well for quite a while.  Eventually, a levee will fail.  Far less likely will multiple levees fail, and the event that would cause multiple failures will also likely go beyond what we actually accomplish to protect them now, regardless of the current wild-eyed rhetoric.  Perhaps we should look at smaller-scale solutions to a recurring issue, rather than panicking about a potential catastrophe.

And for the record, I was born and raised on the Delta, and I live on the Delta now, as do my parents, a sister, and a nephew.


NorCal Cazadora said...

Dude, you should pitch this to the Bee - this viewpoint needs to be heard!

Josh said...

I can never seem to get traction with the Bee... perhaps you could steal it from me and pitch it to them?

geomusicon said...

I'm not convinced that this is bad science. My experience is that op pieces don't include sources and are not peer-reviewed. Have you checked out his website and CV to see his peer-reviewed paper on the topic? He is an environmental engineer...I would be very surprised if he doesn't have a wealth of his own peer-reviewed data to support his claims.

Josh said...

geo, thanks for stopping by!

In my post here, I note that I did find the sources he put up. Click on the link I put up to his post, and check them out. The ones I looked in on are either from the Army Corps of Engineers, or from sources that do not fully support the need for tree removal to the extent the Corps (and this Prof) are calling for.

Op-ed pieces are not peer reviewed, true, but any time somebody makes a claim to fact, they sure as heck better have at least one source for people to check on ("according to ___, blah blah"). That is just good op-ed writing practice.

Besides, the State of California's experts firmly believe that tree removal will be dangerous.

We are past the "have an expert inform us" phase of this controversy, and well into the, "the science for such a dramatic act must be shown, and it must be completely convincing." His own argument is unconvincing, as are his sources. Add to that the fact that he didn't even bother to point us in the direction of scientific evidence in his public testimony, and we are led nowhere, except by his title. At this point, title alone don't cut it.