Should Your Family Evacuate?
Whether or not to evacuate in the event of a hurricane? Given the forecast for an unusually active hurricane season, this is a question thousands of Houston area families may have to face this year. Unfortunately, for most the answer is not as clear as we might hope. Many emergency managers recite the well known adage, "run from the water; hide from the wind." As a general proposition this is good advice and supported by the statistical evidence that the vast majority of deaths in hurricanes are caused by drowning. However, attempting to interpret this admonishment in residents' individual situations is not always clear and, I believe, there are significant exceptions to this general rule.

We discovered in Hurricane Rita that there are very serious consequences from the decision to evacuate. Approximately 150 individuals died in the Rita evacuation. Most were elderly and died from stress-related afflictions. A few died from carbon monoxide affixation while sitting in an idling automobile. Of course, hundreds of thousands were trapped in miserable circumstances. While evacuation plans have greatly improved since Rita, she proved that the idea that evacuating is "better-safe-than-sorry" is not necessarily accurate. There is one group for which the answer is very clear. If you live in the State designated evacuation zones you must evacuate. These are areas that have been identified by the State as likely to be inundated by a hurricane's tidal surge. They are demarcated by zip

code. Residents of these areas have no hoice. They must, by law, evacuate. You can find out if you live in one of the surge zones at: http://www.hcoem.org/documents/EvacuationMap.pdf

For any of you that live in those areas and are thinking that you might ignore the evacuation order, think again. A hurricane tidal surge is like a tsunami that keeping coming for hours. As the surge destroys structures in its path, the flotsam created from that debris becomes a battering ram that flattens anything in its path. If you doubt this, go on-line and do a search for pictures of the Mississippi coast after Katrina. In the area hardest hit by the surge it appears that God took his hand and wiped everything clean for a mile or so inland. And the water coming at you is not pristine beach water. It has picked up everything in its path, including oil, sewer from over-run

treatment plants, chemicals and dead animals. It is a filthy, polluted soup that can kill you. If you live in the surge zone and do not evacuate, you are seriously jeopardizing your life and your loved ones who live with you.

If you do not live in the surge zones, the question of whether you should evacuate becomes much more difficult. At the outset let me say that absent special circumstances, you should not to evacuate because you are concerned that you may lose electricity. If you are only concerned that you will not have electricity you will be much better served to wait out the storm and see if you lose service or not. If you do, then you can leave after the storm has passed and the roads are clear.

This is especially advisable when you consider the degree of forecast uncertainty that still exists. When Rita was 24 hours from landfall, the area in which there was a one-in-four chance of being the direct hit was still almost 250 miles wide. Considering that we will have to call an evacuation in the 48-72 hours ahead of landfall, many calls for evacuation will likely be false alarms. If you evacuate every time a storm threatens our area because you are concerned that you will lose power, you may find yourself on the road a lot for no reason. For most residents who do not live in the hurricane evacuation zones, sheltering place or, as Judge Emmett has now made famous, "hunkering down" will be the best option. However, there are some good reasons for people living outside the surge zones to evacuate or shelter in the area in a location other than their home. There are principally two risks that you should assess.

Rita Cone of Uncertainty 24 hours before landfall

The first is the risk from wind. A Category 4 storm will have 100+mph winds extending as far inland as Montgomery County. Most structures will survive even these winds. I took a helicopter flight over the path of Rita. Many homes lost their roofs and had significant water damage, but few totally collapsed.

There are, however, significant exceptions. One, of course, is mobile homes. If you live in a mobile home and you are anywhere near the central wind cone, you should leave or find other shelter. The other exception is trees. When I took my helicopter tour of the Rita path it was hard to comprehend the number of trees that were blown down. Pine trees are particularly problematic. On that flight I saw a number of instances where a pine tree had fallen through a house, cutting it in two like a knife going through a cake. If you have large trees in your yard (and particular pine trees) that would fall on your house if they came down, I would recommend that you evacuate or find other shelter.

Even if you do not have either of these special risks to deal with, you should be mindful that while a hundred-mile-per-hour wind might not blow down your house, it will pick up all sorts of things and turn them into lethal projectiles. This is particularly dangerous for homes that have large plate glass windows. If you have this situation and are unable to secure the windows with plywood or other protective covers, again, I would leave or find other shelter.

In addition to the wind, residents outside the surge should also consider their vulnerability to upland flooding. This is flooding that is caused not by the hurricane pushing the Gulf of Mexico up on us, but rather from the storm dumping torrential rainfall on the watershed and flooding the bayou system. The tidal surge can exacerbate upland flooding by acting as dam and not allowing the bayous to drain as they would normally.

Rice professor, Phil Bedient, has created a model that projects flooding in the event of a simultaneous 22-foot surge and a 100-year rainfall. The model shows flooding over an enormous area extending as far west as SH99 and as far north as Beltway 8. The Brays Bayou and White Oak Bayou watersheds are particular vulnerable to this type of flooding. While having a bayou back up into your house does not create the same danger as the tidal surge, there are risks associated with any flooding and it is obviously extremely unpleasant. I believe that anyone living in the 100-year flood plain should also evacuate or find other shelter on higher ground in the event of a storm with a forecast of heavy rainfall. You can determine whether your home is in this area by accessing http://maps2.tsarp.org/tsarp/.

But here is the most important point, make your plans for evacuating or sheltering in place now. Do not wait to decide if you are going to evacuate and where you are going to go as a storm is grinding down on us in the Gulf. We all tend to make poor choices when under stress and people around us are panicking. Also, the last few storms we have faced have originated in Caribbean which gave us nearly a week to prepare for their arrival. However, there have been a number of storms that originated in the Gulf giving us as little as 48-72 hours to make preparations.

Set aside some time over the next couple of weekends and think about this issue. Do the research and determine if you are in a surge zone or a 100-year flood plain. Decide in advance at what level storm you will evacuate or seek alternative shelter. Make a plan regarding where you will go and what you will need to take with you. If you are going to shelter in place make a plan on what you will need to do to be ready. Make checklists. There is a detailed hurricane planning software that is available free on-line at www.OneStorm.org.

In the middle of the night on Wednesday, September 21, 2005, the Houston region was staring down a loaded gun barrel. Hurricane Rita was on a course to make landfall around Freeport and one of the strongest Category 5 hurricanes on record. Similarly even though Hurricane Ike came ashore as a Category 2 storm, if he had made landfall 20-20 to the west, the storm surge could have easily been ten feet higher. The truth is that we have dodged two bullets in just the last four years. We now know that a catastrophic storm making landfall is not just a hypothetical possibility. We also know what a mess a full scale evacuation of the area can be. Even with the improvement made to the evacuation plans since Rita, evacuating 1-2 million residents is never going to be a pretty picture. Nonetheless, you can minimize the effect of a major storm on your family by planning ahead. Do it today.

The Ike Dike:
A Dutch Perspective

In case you missed it over the weekend, the Chronicle published some of my reflections the levee system in the Netherlands that I had the opportunity to visit recently. http://www.chron.com/disp/story.mpl/editorial/outlook/6525027.html

There are many interesting aspects to the Dutch system, but undoubtedly the most impressive is the massive sea gate at Maeslantkering. This structure was built to provide a means to stop tidal surge from flooding the area around Rotterdam by backing up the Nieuwe Waterweg (part of the Rhine estuary system). The problem that the Dutch faced was that the Nieuwe Waterweg is one of the busiest waterways in the world, with a ship passing though it on the average of every 8 minutes. As a result, a traditional lock system was unworkable.

The reason the Maeslantkering sea gate is of particular interest to our area, is that it suggests a possible solution to building a levee system to protect the Texas Gulf Coast from a hurricane surge. To accomplish this, it would be necessary to have the means to block off the Houston Ship Channel, a daunting task to say the least.

The most logical place to attempt such a feat would be between the tip of the Bolivar Peninsula and the east end of Galveston Island. At that point there is about 1.5-mile expanse of water that begins very shallow on both sides but drops off fairly quickly to a depth of 15-20 feet then gradually deepens to the Ship Channel's depth of 40 feet.

The Ship Channel is about 500 feet wide in this area, however, the water immediately outside the channel is over 30 feet deep providing some maneuvering latitude. Preliminary concepts, such as Bill Merrill's design, contemplate a levee stretching from each side to a Maeslantkering-like sea gate across the Ship Channel. It is clear that a structure of that size can feasibly be constructed. The Maeslantkering gate actually spans about 1200 feet, more than twice the width of the Ship Channel.



Recently, the Dutch officials that operate the gate were kind enough to give me a tour of the facility. It is an imposing structure. In many ways it reminded me of an offshore drilling rig lying on its side.



The design is ingenious, but the technology is surprising simple. The arched barriers are actually large submarines. In their "resting" position, they float. When the gate is closed, small diesel engines on each side float the gates into the river using a simple cog and cam track. Once they are in place, they are flooded and sink to the river bottom.

The river bottom has been reinforced with a footing that is topped with enormous concrete blocks so that the gate has a hard surface on which it can sit. Interestingly, the bottom actually silts in over time and the gates initially "land" on this silt, about three feet above the concrete footings. However, the rush of water under the gate clears out the silt in about an hour when the gates make their final landing on the concrete sill.

The arched barriers are supported by trusses that are attached to a gigantic ball joint. The ball joint allows the trusses to articulate horizontally and vertically. Each arm can withstand a force of 70,000 tons.


The gates can be opened and closed in a matter of hours. In its ten-year history it has only been closed once on account of a storm. However, there is a test closing annually just prior to the start of the Dutch storm season. (BTW, the test closing this year is September 19-21. It apparently attracts thousands of observers. If my schedule permits, I intend to be one.)


The Dutch began contemplating a surge barrier in this area in 1979. Less than 20 years later, the Maeslantkering sea gate was completed in 1997. The total cost in 1997, was about €450 million (approximately $630 million). The annual maintenance is about €5 million ($7 million).

The gates are about 70 feet tall. With a channel depth of about 50 feet, the gates create about a 20-foot wall above normal tide levels.


One interesting aspect of the gate is that it does not completely shut off all of the water. There is about a five-foot gap between the gates to prevent them from colliding into each other. Also, some water flows around the end of the gates in the channels cut for their resting position. According to the Dutch officials, the gates block about 98% of the water, assuming that the surge does not over top the gates. However, to reduce the flood level on the back side of the gate it is not necessary to block all of the water.

There are, of course many questions as to whether such a sea gate is feasible for the Houston Ship Channel. Before undertaking what would likely be a billion dollar plus project, we would certainly want to conduct an extensive study, including an examination of the potential environmental impacts. Nonetheless, I found the Dutch will to overcome the sea and protect their communities from its ravages inspiring. I think theirs is an example we should follow. I do not believe that doing nothing is an option. I guess I must have some Dutch blood.

For more information see:
http://www.keringhuis.nl/engels/home_flash.html

Click here to see the Keringuis Website

Click here to view the Video "Storm Surge Barrier on the Nieuwe Waterweg"

The Ike Dike

Last week the Governor's Commission studying the Hurricane Ike recovery unanimously recommended to the Governor and the Legislature that a study be funded to determine the feasibility of a comprehensive levee system to protect the Texas Gulf Coast from future storm surges. The recommendation was prompted by presentations made to the Commission by Texas A&M of a concept levee system that would block storm surges from entering Galveston Bay. The proposed system has been dubbed the "Ike Dike."

To be perfectly honest, when I first heard the idea, I thought it was a bit outlandish. But as the Commission has studied the issue, all of us became convinced that the concept warrants a serious and detailed consideration.

The Ike Dike is the brainchild of Texas A&M Galveston's Bill Merrill. To review his PowerPoint presentation click here. The dike envisioned by Merrill would extend from High Island to somewhere south of the San Luis Pass and is specifically designed to protect the Galveston Bay environs. However, the Commission's recommendation is that a study that would include the entire Texas Gulf Coast.

The project would basically create a 17-foot wall along its entire length, incorporating the existing Galveston seawall. There are several possible designs, but the one that probably is most viable would be building a levee along the existing FM3005 and SH87 right of ways. These are already at about a 5-foot elevation, so they would only have to be raised by twelve feet to get the design elevation.

Of course, the challenging part is how to keep the surge from barreling up Houston Ship Channel through the Bolivar Roads. This will require creating a gate that will close off a nearly two-mile stretch of open water. As bizarre as this may sound, there is actually such a barrier across the Rotterdam channel in the Netherlands that spans a wider gap. Clearly, we do not have enough information at this time to make an informed judgment on the feasibility or advisability of such a project. However, the Commission did ask some basic questions. This is what we found.

Bolivar Roads

Cost. The obvious questions are "how much" and "how would we pay for it." Merrill estimates that the Galveston Bay portion of such a levee would cost about $3 billion in today's dollars. This frankly would be a fairly modest investment comparatively speaking. The estimated damage from Ike alone is in excess of $30 billion. Not all of the damage would have been prevented by such a levee system, but clearly it would pay for itself with just one such storm. It is also comparable to other major public works projects in this area. The expansion of the Katy Freeway and Metro's LRT project both have similar price tags.

The federal government would likely be willing to substantially subsidize such a project since it would dramatically reduce claims on the Federal Flood Insurance Program. But even if Texas had to pay for the project alone, it would only take about 5-6¢ property tax on the affected counties to finance the project over 30 years. I think it is clear that if Merrill's cost estimates are anywhere close to accurate, the financial hurdle may the lowest one.

One of the more disturbing pieces of information the Commission heard was that industrial and commercial concerns are now reluctant to invest along the Gulf Coast because of its vulnerability to storm surge. It may be that if we do not undertake some protective measures, we will see economic growth stunted in our region by an amount far greater than the cost of such a project.

Will it Work? A number of Commission members were skeptical about whether such a levee could really hold back a Category 5 storm surge. Merrill points out that the Dutch have been holding back the North Sea for centuries, a seemingly more daunting task.

Some of the Commission's questions centered on whether a 17-foot levee was high enough. At places the Katrina storm surge was measured as high as 28 feet. However, the 20+-foot measurements are all inland and not at the coast. A storm surge is exaggerated as it pushes its way into the confines of bays and rivers. According to Merrill, a 17-foot system will stop 95% of the storm surges ever measured. Also, even if a storm surge topped the levee, the effects on the inland areas would still be dramatically minimized.

Environmental Impact. The environmental impact of such a levee system will be the most vexing question. There are obvious and significant environmental benefits. One only need visit Galveston Bay today to see the adverse impact of Ike. Also, friends in the petrochemical industry have told me that if we ever get an Ike-like surge directly up the Houston Ship Channel the ecological consequences will be disastrous; which is easy to believe.

On the other hand, there could be adverse long-term, and perhaps, unintended consequences from constructing such a system. Some environmentalists argue that hurricanes actually have a long term beneficial effect on the estuary system.

One of the concerns raised immediately by environmentalists is the effect on the exchange of water flows between Galveston Bay and the Gulf. In order to build the sea gate that would close off the Bolivar Roads, the opening would have to be narrowed from the current width of nearly two miles to about 1000 feet. Environmentalists worry that this stricture would impede the flow of Gulf water into the Bay along with various species that migrate between the Gulf and the Bay. It might also alter the salinity of the Bay and thereby negatively impact some species.

Merrill is convinced this concern can be addressed by designing the dike to accommodate a sufficient Gulf water inflow. But even if that is the case, there will be many other environmental concerns such a massive project will raise. Part of the vetting process must address each of these with scientific integrity.

Conclusion. Thanks to Ike, I experienced first-hand the effects of a storm surge on my hometown of Kemah. I also remember returning to a nearly totally destroyed Kemah as a child after Hurricane Carla. Therefore, I am probably not entirely objective on this subject. Nonetheless, I have seen the human and financial toll a storm surge has on families and communities. It is truly devastating. If we can responsibly protect future generations of Texans from hurricane storm surges, it would be a great legacy to leave our children and grandchildren.