Mapping a Disaster

Like a lot of people for the last few days, I have been watching a lot of news programs about Hurricane Katrina. I have been increasingly dissatisfied with the reporting that I see going on, since I feel that the bigger questions have so far gone unasked. Since I have a blog, and much of the trad media have been freaking out for a long time now about the crappy “reporting” going on in the blogsphere, I got the not so original idea to do my own researching and reporting about Katrina, for you, my elusive reader.

Here are some questions that I don’t think anyone has been asking nearly as loud as they should be, if they’re being asked at all:

1) Why haven’t the big guns rolled/floated/parachuted into downtown NOLA yet? Clearly, with breaking levees and stranded people inside attics in rising water, they are woefully undersupplied, and when people don’t have supplies, they are going to go apeshit and do what they feel that they have to to take care of themselves. (Hypothesis: We would normally send in the National Guard and other groups. The problem is twofold: first, they can’t get past the flooding to the city with the standard apre-hurricane recovery equipment, and secondly, there aren’t the usual numbers of regular military and National Guard troops and supplies that would be here if we weren’t at war in Afghanistan and Iraq.)

2) Why did I get the impression that the officials were basically giving up on people who planned to stay in their homes on Sunday in NOLA?

3) Who wasted time thinking about sandbagging a 300-yard long breach in a levee? I checked this with a trained engineer who works for the Navy, but who was strictly speaking as a private citizen with engineering knowledge, and he indicated to me that it would take more than sandbags to seal a levee breach that large. He suggested that the only way they could at this point tackle the problem would be to use helicopters to place large boulders, one at a time, in the breach. It’s probably why the promised thousands of sandbags that were supposed to be dumped into the breach never came since the helicopter was diverted from that operation to search and rescue–because sandbagging a 300 yard breach in a levee that has water pouring over it is absolutely futile. [Note: Of course, neither of us at that time thought about very very large sandbags, which, at least temporarily, helped with the problem…]

There are other questions, but they will have to wait. Here is what I really wanted to share with you right now.

FEMA has things that everyone in the country should know about and use, called Flood Maps. One of the many many truly worthy things that the feds have done with that tax money of ours is to map 100 and 500 year flood levels on maps of your local community. I live in a coastal region, as you probably know. We just got the new set of the local Flood Maps at work, and they take up about 1 cubic foot of storage space in a cardboard box. You can look up your street on these things and tell if you need to buy flood insurance. If your street appears on the map, you would be very very well advised to cough up the couple hundred bucks a year to protect the contents of your home from ground-up flooding. Your homeowners policy probably does NOT cover this type of flooding. It is Bad For You not to have it.

Anyway, I already knew from drawing breath and being interested in things that NOLA is mostly below sea level. I have long known of the problems of dealing with a large hurricane in NOLA due to their elevation. I decided to see on the official map exactly how bad the situation is. Head over to http://www.esri.com/hazards/makemap.html to take a look at your community map. Before you do, though, take a look at this with me. Enter New Orleans, LA into the page, leaving the Flood Hazard Mapping option selected, then hit enter. You’ll get this pretty green and blue map, until you read the legend and see what you’re looking at. [This site is no longer available. -Amanda 3/3/2014.]

Here we see downtown NOLA, just the place you’re seeing on the news. See the darker green color? That’s the 100 year flood level, the sort of flood you’d expect to see, on average, separated by a mean time of 100 years or so. We can go a couple hundred years before we see it, but if you average it out over geologic time, you’ll see it about that often. Ten times a millennium. Okay, that’s clearly flooding right now. Now, see the lighter pea green areas? That’s the 500 year flood level. Yikes! That leaves basically NO land that is not known to be vulnerable to some kind of major flooding. There is a bit of gray area on the map, which is technically a spot where they have no data, but it seems to be a bridge or possibly canal or levee. Anyway, you can see a problem here.

Now, head on over to a marvelous elevation map from the Washington Post. Stuff in green, if you read the legend, shows you that these sections of town are, bless us, above sea level. The yellow and red sections are progressively lower and lower elevations below sea level. See how the lowest areas are along the levee areas by Lake P, then some other not quite as low, but still red areas closer to the downtown area? These are the areas with flooding now, it seems. Now, do you see the dotted black and white line? Look on the legend. This area is shown in cross section. On either side is water above the level of the land. Now, see how the Lake P. side is the lowest, then there is a small ridge, then a shallower trough? It looks from this as though now that the levees are breaching, you will see almost the entire city submerged in at least some water, in some places very deep water.

These two maps measure the problem coldly for us. People in attics in the red area will drown if the levee breach affects their area to the point where the flood waters rise as little as another 3 or 4 feet, at least in some places where we’re seeing people being rescued with only that much water to spare in their attics. Let me be clear on this point: the water is still coming through those levee breaches, and so far, nothing has been able to be done to stop it. I fear that if I can work this out, so can the powers that be, and that is part of why the only things we’re seeing done is the rescue of these people. I know that the powers that be would love to get portable toilets and food and water to the people on the Interstate and in the Superdome. They’d love to get the prisoners housed in a secure and safe prison, too. But all that must wait while the only vehicles that can get around fast enough, boats and helicopters, work to get these people out of the still rising water and at least onto those baking hot Interstate overpasses where at least, they won’t drown.

Leave a Reply

Your email address will not be published. Required fields are marked *

*