Watershed Texas

Maeslant Barrier, Netherlands. Google Earth, December 2018

The US Army Corps of Engineers has just chosen the Ike Dike as the Tentatively Selected Plan (TSP) for coastal protection on the Upper Texas Gulf Coast. There is controversy over this choice, but all are agreed that “something must be done.”  We have put people and facilities increasingly in harm’s way over the years. Putting something between people and the harm, like an Ike Dike or one of its progenies (the Rice Mid-Bay Dike for example), seems like the most obvious thing to do.

I am not going to say that a large dike should not be built. I am suggesting, however, that we might not have enough information to make a rational choice.

We have not been told what the risk of failure is for a large dike.  Do levees or dikes fail?  Of course.  Dikes fail through a variety of mechanisms, overtopping one of the most common ways. Failure probabilities can be quantified, approximately to be sure, but within a well-defined range. There is no evidence that such an analysis has been done for the Ike Dike.

What happens the day the dike breaks? If the Ike Dike were to be breached, would it be a catastrophic failure or just a small rivulet of water down the sides?  Indications are that overtopping would be catastrophic.

This is an important question because the security that large dikes promise almost always induce development in areas that otherwise would not have been developed. If the dike fails, these people could be very much in harm’s way. Floodplain scientists call this inducement a “moral hazard.”

We experienced this very situation with Harvey. Our large storm reservoirs to our west came very close to overtopping, and flow had to be released at higher rates than ever intended. The people flooded from that release are just a small fraction of the people that would be impacted by an actual failure of one or both of the dams. Sixty years after construction there are in fact serious questions about the integrity of the dams.

The dams in a very real sense induced development much closer to Buffalo Bayou than anyone would have considered prudent before the dams were built. Engineers considered the floodplain to have been greatly reduced because of the dams. The “shadow” of that floodplain is still there, however, and that is where flooding occurred during Harvey. Engineers did not think a buffer would be needed. After all, who would build a dam or levee that could fail?

We also saw this with the levee districts in Ft. Bend County. No breach occurred, but we came so very close to overtopping. No one “protected” by those levees should be breathing easy.

With Harvey, we have now come close enough to see what catastrophic levee or dike failure might look like.

In terms of surge protection, is our choice then just between building a massive dike system, or taking no action at all?  Such is the choice outlined in the Corps Coastal Protection Feasibility Study.

There is a third way, but it is not nearly as easy as building an Ike Dike. But the payoffs might be much greater.

The University of Texas Medical Branch on Galveston Island took a very serious hit from Ike in 2008, but they came back way more resilient than they were before. At a recent symposium, UTMB facility managers outlined the impressive steps they took after Ike. When asked if they would have undertaken this massive $1 billion hardening if the Ike Dike had been in place, they responded unequivocally and without hesitation that they very definitely would not have done so.

Therein lies exposed the moral hazard. UTMB would have been perfectly happy to deposit their trust with the Ike Dike, and forgo the expense they undertook to harden their facility. But which way would be safer for them, or for that matter for others exposed to the risk of catastrophic surge damage? Would it better to spread the risk and the responsibility, or would it be wiser to put all of our eggs into the Ike Dike basket? This is the discussion we need to be having in terms of coastal protection.

But what about our highly-vulnerable petrochemical complex along the ship channel?  Could they harden their infrastructure? There are in fact best practices developed by the industry to harden facilities located in hazardous areas such as storm surge zones. Shouldn’t the burden of this hardening be borne primarily by industry?

In addition to hardening critical structures, what could we do in terms of planning for communities deep in the storm surge zone that would make them at least as safe what the Ike Dike purports to do?

First, we stay out of harm’s way, or build in a way consistent with the danger. Elevation is the number one predictor of damage in surge zones. When folks on Bolivar built back from Ike, they built back on stilts that were at significantly higher elevations above the ground than before. And they are much the safer because of it.

We could build community safe rooms, places of refuge we can go to if we can’t evacuate on time. Mixed-use development, particularly of the walkable variety, provides these kinds of spaces as a matter of course. The Galveston Strand is an excellent example – many flocked there and were saved during the Great Storm of 1900. The Strand, interestingly, is the walkable pattern so many communities are looking for today.

Building resilient communities on higher ground in the coastal zone is not a simple matter. But the payoff would be greater than what any dike could provide. Less risk but stronger communities. The problem is that getting there would require serious political leadership. And planning does not seem to be in our genes.

Even so, we could have a serious conversation about coastal protection that considers all the possibilities. Community conversation is the first step towards resilient communities. We can start that right now!

Jacob is Professor and Extension Specialist with Texas A&M  AgriLife Extension through the Department of Recreation, Park, and Tourism Sciences. He is the director of the Texas Community Watershed Partners based in Clear Lake. The opinions expressed here are strictly his own.