(Note this article references my previous post entitled “Gustav and New Orleans: A Political Risk Assessment for the Republican Decision Maker” dated Saturday, 08-30-08, and “UPDATE: Gustav and New Orleans: A Political Risk Assessment for the Republican Decision Maker” dated Sunday, 08-31-08).

Events are rapidly unfolding.  According to the National Weather Service, National Hurricane Center Advisory Number 31:

• The center of Gustav is not poised to strike New Orleans when the storm makes landfall.

• New Orleans will experience at least tropical storm force winds, and perhaps hurricane force winds depending on whether the storm veers slightly east (note this information was derived from a procedure, whether visually or computationally, that the NHC labels as “experimental”).

• And, New Orleans, with a probability [90%, 100%] will experience a storm surge.

• Gustav, however will, with near certain likeliness, be a category 3 storm or less (>96% chances), with category 2 being the most likely storm intensity.  Since the storm will likely not hit New Orleans dead on and at landfall the storm will be weaker than Katrina (which was a category 3 storm when it hit New Orleans dead on), the effects of Gustav will most likely not be as bad Katrina.

Assessment Revisited

Because there is no question at this point that New Orleans is set to experience an appreciable storm surge due to the forces of Gustav, I revised the possibility tree to exclude scenarios E7 (i.e., Pr(A2) = 0; Pr(A1) = 1) and E1 through E3 (i.e., Pr(B1) = 0; Pr(B2) = 1) as follows:

All other probabilities remain unchanged (even if they are irrelevant given that their conditionals are no longer deemed plausible).  Thus, I revised my probability estimates for the remaining scenarios as follows:

Recall from my previous post that the political outcomes for scenarios E4 through E6 (which I leave unchanged) is as follows:

• E4: “-”
• E5: “-”
• E6: “++”

Now, with both consequence and likeliness in hand, the political risk profile charactering the uncertainty associated with near-term political outcomes can be illustrated as follows:

Summary of Results

Based on my revised risk profile derived from all assumptions implicit in the scope of this analysis, the most likely scenario is that the Republicans will benefit from Gustav, at least in the near term.  In fact, the analysis assigns odds of 19:1 in favor of the Republicans.  Perhaps this is the reason that Time Magazine is posing the question “McCain to Seize the Stormy Moment?“  But, the CCAN blog notes that Gustav is another example of extreme weather afflicting an nation in denial.  Perhaps the Democrats can spin this whole situation their way by emphasizing Republican denial of global warming, citing Gustav as “evidence” in support of the global warming is real hypothesis.  My particular analysis, however, does not look into this issue.

Now, given that my conclusions rely on fewer assumptions than with my previous analysis, I assign MODERATE CONFIDENCE to this analysis.  This is the highest level of confidence I can assign given the time I have available for analysis and my level of expertise in the subject.  I must remind readers here that the scope of this analysis is focused on the NOHPS, and does not consider the likeliness and political outcomes for some other non-New Orleans disaster (that could have been prevented by something designed and installed to prevent it).

I think the next post on this subject will come when Gustav is done.  Let’s see what happens…

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(Note this article references my previous post entitled “Gustav and New Orleans: A Political Risk Assessment for the Republican Decision Maker” dated Saturday, 08-30-08).

Revision of Likeliness Estimates

According to the National Weather Service, National Hurricane Center, Gustav is veering to the right (albeit slightly) of yesterday’s projected storm track centerline (see below).  Moreover, the National Weather Service has deemed it sufficiently likely that Gustav will significantly impact New Orleans that it has issued a Hurricane Warning to the city and points all along the Louisiana and Mississippi coastlines (and a little bit of Alabama too).  Accordingly, I revise my probability estimate for the event that Gustav will afflict New Orleans in an appreciable way (in terms of storm surge) as follows:

• Pr(A1) = 0.75 (increase from yesterday’s 0.50)
• Pr(A2) = 0.25 (corresponding decrease from yesterday)

Note that I did not use Bayes’ Theorem to update my probability estimates, but rather did a complete reassessment of the probability.  Also note I continue to entertain non-zero chances that the storm will not afflict New Orleans since the storm track envelope admits some degree of likeliness to the storm veering to the west.

Now let’s turn out attention to the time Gustav makes landfall.  According to the right-most figure above, the storm center will probably make landfall sometime between 7AM CDT and 7PM CDT on Monday, 08-31-08.  According to the maximum wind speed probability table (NWS advisory 28, dated 10AM CDT, 08-31-08), the chances that Gustav will be a category 3 storm or greater is [37%, 81%].  Since Katrina was a category 3 storm, lets assume that if Gustav is classified as a category 3 storm or greater at landfall AND the storm is one that is slated to yield an appreciable storm surge affecting the New Orleans Hurricane Protection System, then Gustav will be as bad or worse than Katrina.  Otherwise, it will not be.  With this information, I can revise my probability estimates as follows:

• Pr(B1|A1) = [37%, 81%] (probability that Gustav will be as bad or worse than Katrina)
• Pr(B2|A1) = [19%, 63%] (probability that Gustav will not be as bad or worse than Katrina)

Since the other events C1, C2, D1, and D2 have to do with the integrity of the NOHPS (which is assumed to have not changed in the last day) and the consequences to New Orleans in the event of NOHPS failure (also assumed to be unchanged), the revised probability for the scenarios E1 through E7 is as follows:

Revised Consequence Assessment

The press recently reported to Republican decisions that, though most likely pursued for unselfish and humanitarian reasons (as they should), can also be viewed as strategies to decrease the potential for unfavorable outcomes and increase the potential for favorable outcomes.  These are as follows:

• As stated by White House Press Secretary Dana Perino (cited by CNN and elsewhere), President Bush and Vice President Cheney will not attend the Republican National Convention in St. Paul Minnesota in person; instead, Bush may address the convention via satellite.
• As reported by CNN (link), RNC organizers are examining options to change the schedule of the convention, to include delaying opening ceremonies, turning the convention into a massive telethon, or postponing the convention altogether.

In the context of this study, these measures may very well decrease the severity of the resulting political fall-out in the event of a NOHPS failure, but perhaps not by much because after all, the NOHPS failed despite having three years to rebuild.  On the flip side, if Gustav does afflict New Orleans in an appreciable way (again with respect to storm surge along the NOHPS), and the NOHPS successfully protects the city, then the Republicans will surely emphasize the improved ability of the federal government (under the Bush administration) to prepare for and protect against natural perils.  In this case, more of the same might not be viewed as being all that bad with respect to domestic preparedness (and perhaps by extension, homeland security).  But now, in the event that Gustav does not afflict New Orleans, the political fallout is slightly in favor of the Republicans since they are taking preventive measures to protect the Gulf coast across the board, and you can’t deny that doing a good job at this by putting the people first (which I argue they will do) will garner some brownie points from the electorate.

Given the above, I revise my political outcome assessment as follows:

• E1: unchanged at  “–”
• E2: unchanged at “-”
• E3: unchanged at “++”
• E4: unchanged at “–”
• E5: unchanged at “-”
• E6: improved to “++”
• E7: improved to “+” (may change back to “N” if the Democrats can somehow display on a national stage that they are doing something too)

Given the revised likeliness and political outcome assessments above, the revised risk profile over the space of political outcomes is as follows:

Revised Results

Based on the revised risk profile above, we can draw the following revised conclusions:

• The most likely major scenario is that the Republicans will benefit from Gustav [86%, 93%]
• The must less likely scenario is that the Republican campaign will suffer from the effects of Gustave [7%, 14%]
• It seems at this point that Republicans will feel something given that the probability of a neutral or “no effect” outcome is near zero at this stage

From the Democrat perspective, one strategy to mitigate the Democrat risk is to do something that will gain them visibility on the national stage in relation to Gustav preparedness.  A visible substantial effort may serve to transfer some of the Republican benefits resulting from scenario E7 back to the neutral position (I doubt they can do much to pull any support in their favor for this scenario).  But even still, given the probability assessment being what it is, the ordering of the major scenarios will remain unchanged.

CAVEAT: Given the probabilistic nature of my assessment, the only verifiable portion of my assessment is whether or not the neutral outcome is realized.  But this requires me to stand by my assessment in light of new information (which I am sure to come across).  I suspect that I will find myself updating this analysis again sometime in the next day or so.

Note: as stated in my previous post, I assign LOW CONFIDENCE to this analysis given that I am not an expert in hydrodynamics, nor am I an expert in politics and political sentiment.

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At 5PM EST, Saturday, 08/30/08, the National Weather Service, National Hurricane Center released their estimate of probability of storm surge afflicting New Orleans sometime over the next 72 hours (see below):

Mayor Ray Nagin of New Orleans is labeling Gustav as the “mother of all storms.”  Apparently, New Orleans (the brownish colored area amidst the probability contour) has between a 40-60% probability of storm surge (it is hard to tell whether New Orleans is in the yellow, brown, or partial to both).  What was my estimate from the 2PM EST data?  My estimate was 50% that Gustav would result in an appreciable storm surge.  So, I suppose this is confirmation of my initial estimate (perhaps not, but it is nice to think so).  The next question is whether Gustav will result in storm surges as bad or worse than Katrina.  Based on what I am reading, I suspect so, but we shall see.

(note: this post references my previous post from just a few minutes ago)

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In light of the temporal intersection of two very significant events – Hurricane Gustav and the Republican National Convention – I can’t help but perform a risk assessment of Gustav from the point of view of the Republican presidential campaign.  While one can speculate on a variety of bad things that could come out of Gustav that could affect Republicans or Democrats, I will focus my attention on the simple questions “will Gustav afflict New Orleans?” and “what if it does?”

What Can Happen?: The Republican Point of View

Let’s begin this analysis by developing a full set of hypotheses and sub-hypotheses for this study that are of interest to the Republican presidential campaign.  The events of concern for this analysis center on Hurricane Gustav and New Orleans.  The outcomes of concern are assessed in terms of “delta-support” for the Republican presidential campaign, that is, whether in the end the situation increases support, decreases support, or does not effect support for the presidential candidate in the time frame immediately following Gustav.  This analysis does not examine whether the “delta-support” can be sustained for the remainder of the election season.

The first question is whether Gustav will afflict New Orleans?  More specifically, will Gustav afflict New Orleans in such a way that causes an appreciable storm surge?  There are two possible answers to this question:

• A1: Gustav will afflict New Orleans
• A2: Gustav will not afflict New Orleans

Since the scope of this risk assessment is on the risks to the Republican party due to Gustav afflicting New Orleans, we will restrict most of our attention to A1.  This hypotheses can be further divided into several sub-hypotheses as follows:

• B1: Gustav will be as bad as or worse than Katrina in terms of intensity
• B2: Gustav will not be as bad as Katrina in terms of intensity

I partitioned A1 into B1 and B2 above for a simple reason: it is easier to make comparisons between Gustav and Katrina if they are similar in intensity than if Gustav is weaker than Katrina.

The next issue to consider is the levees – given that Gustav afflicts New Orleans, we have the following set of hypotheses:

• C1: The hurricane protection system will fail to protect New Orleans
• C2: The hurricane protection system will successfully protect New Orleans

If C1 occurs, then all is well for New Orleans (and as we will see later, potentially very good for the Republicans).  However, if C2 occurs, then we have two more hypotheses to consider:

• D1: The consequences of breach are disastrous
• D2: The consequences of breach are not disastrous

For the purposes of this analysis we need not qualify consequence in terms other than “disastrous” or “not disastrous” as it would not offer any additional insight in light of the cost of a more refined analysis.

Given Ai, Bj, Ck, and Dm, we can construct a possibility tree for this situation as shown below, where there are 7 possible end points, some good, some bad, and some neutral from the Replublican campaign point of view.  This possibility tree defines a complete (i.e., exhaustive) set of distinct (i.e., mutually exclusive) hypotheses relevant to this assessment.

How Likely Is It To Happen? (Likeliness Assessment)

This next phase of the analysis assesses the likeliness of events A1, A2, B1, B2, C1, C2, D1, and D2.  Let’s begin with A1 and A2.  According to the National Weather Service in Advisory 24 released at 2:00pm EST on Saturday 8/30/08, New Orleans falls within the 67% probability envelope of potential hurricane paths (see below).  This means that NWS assigns a 2:1 odds that Gustav’s path will pass within a region shown in white.  The residual 33% of total probability is reserved for the region outside of the white envelope, where there exists hurricane paths also with the potential to afflict New Orleans.

So, what is the probability that Gustav will cause a storm surge to occur that challenges the New Orleans hurricane protection system? If you examine the potential storm track of Gustav, the region to the right of the envelope centerline corresponds to a family of storm tracks that seem to push water toward New Orleans.  The family of storm tracks to the left of the centerline seems to push water toward the coast of western Louisiana and the eastern shore of Texas.  Treating the centerline as the median line, and assuming any storm track to the left of the median will not cause an appreciable storm surge and everything to the right of the centerline will, I assess it to be about even odds (50% chance) that Gustav will afflict New Orleans in an appreciable way.  Thus:

• Pr(A1) = 0.5
• Pr(A2) = 0.5

From the historical record maintained by the NOAA Coastal Services Center Historical Hurricane Tracks database, note that Katrina’s path (shown below), too, seemed to push water toward New Orleans.

To answer the question whether Gustav is poised to be as bad or worse than Katrina given that Gustav causes an appreciable storm surge, let’s compare the projected storm track of Gustav with that of Katrina.

What does this tell us?  First, note that starting at some point in time when Katrina was north of the western tip of Cuba, Katrina transitioned into a category 4 storm.  Similarly, Gustav as of the time of this image (at the Orange circle), too was a category 4 storm.  For both Katrina and Gustav, the paths between the point of transition of the estimated point of landfall more or less allowed for free movement over a body of water more than willing to fuel the storm’s intensity.   Much like Katrina, I suspect that Gustav will trudge along the Gulf of Mexico toward land, picking up speed along the way.

Also from this figure, the worst part of Gustav (in terms of wind speed) will happen with chances 67% or greater sometime between 8AM EST Monday 9/2/08 and 8AM EST Tuesday 9/3/08.  To see this, just see where the coastline intersects the white uncertainty envelope.  According to National Weather Service Advisory 24, the probability that the storm is a category 3 in or higher storm is 25% or greater.  However, I would argue that were Gustav to follow a trajectory to the left of the storm track centerline, the probability of occurrence would be much higher for category 3 and higher.  But since I lack this information at present, I will settle for the following probability judgement expressed in terms of probability intervals:

• Pr(B1|A1) = [0.25 1.00]
• Pr(B2|A1) = [0.00 0.75]

Now on to the integrity of the New Orleans Hurricane Protection System (NOHPS).  This question is the true object of contention with respect to the purpose of this risk assessment.  Given that Gustav strikes New Orleans, will the NOHPS hold up?  The answer to this question depends on the two factors: the intensity of the storm surge resulting from Gustav, and the structural resistance of the NOHPS with respect to this storm surge.  According to an article in the Seattle Times summarizing US Army Corps of Engineers progress toward upgrading the NOHPS, the $15-billion NOHPS upgrade scheduled for completion in 2011 is only 20% complete.  Of course, one doesn’t improve a system as immense as the NOHPS uniformly, but rather in discrete chunks.  So it is reasonable to assume that 20% project completion means 80% of the length of levees and flood walls in New Orleans is left “as good as old” where “old” = “Pre-Katrina.”  But because the USACE has a lot of smart people engaged in this project, we should assume that the project scheduled fortification of the most vulnerable sections first, leaving fortification of the less vulnerable lengths for later on in the project.  So, this 20% complete might very well mean that the weakest sections have been fixed, with less weak sections on the schedule for future improvement.

That said, I am going to go with the following (admittedly waggish) probability estimates:

• Pr(C1|A1,B1) = 0.20 (20% chance the NOHPS will fail if the storm surge is as bad or worse than Katrina)
• Pr(C2|A1,B1) = 0.80 (80% chance the NOHPS will not fail if the storm surge is bad or worst than Katrina)
• Pr(C1|A1,B2) = 0.05 (small chance that the NOHPS will fail if the storm surge is not as bas as Katrina)
• Pr(C2|A1,B2) = 0.95 (very high probability that the NOHPS will not fail if the storm surge is not as bad as Katrina)

What remains is to assess the likeliness of D1 and D2.  If the NOHPS fails under conditions as bad or worse than Katrina, it is reasonable to assume that the impacts to New Orleans would be perceived as disastrous (though perhaps not as disastrous as Katrina given Gov. Jindal’s preparedness efforts).  Now, if the NOHPS fails under storm surge conditions not as bad as Katrina, I admit a small chance to the whole thing not turning out to be a disaster, say 10%.  Thus we have:

• Pr(D1|A1,B1,C1) = 1.00 (certain that it will be a disaster if the NOHPS fails and the effects of Gustav are as bad or worse than Katrina)
• Pr(D2|A1,B1,C1) = 0.00 (ditto above)
• Pr(D1|A1,B2,C1) = 0.90 (see comment for the very next probability)
• Pr(D2|A1,B2,C1) = 0.10 (my admission of a small probability that failure of the NOHPS under conditions not as bad as Katrina will not yield a “disaster”)

At this point I have all the probabilities I need and can now calculate the probability for each scenario E1 through E7 as follows (expressed as percentages).  Please ignore the decimal precision as it is a by product of multiplying otherwise imprecise, representative numbers.

What Are the Political Outcomes?

This final step of the risk assessment examines each of the 7 end scenarios and attempts to assess whether each scenario will increase support for the Republican party, decrease support, or have no effect.  A five-level ordinal consequence scale is constructed for expressing outcomes as shown in the table below.

Now let’s rate even scenario E1 through E7 according to how it will impact near term public support for the Republican candidate.

• E1: No one can deny that if Gustav turns out to be Katrina-like or worse AND the NOHPS fails, then the Democrats are in a strong position to argue that the Republican party once again failed to protect New Orleans even when it had 3 years to do so since Katrina.  My bet is that Obama will argue that McCain will just offer “more of the same.”  Thus, I assess the political outcome from this scenario will be “- -” (two minuses, or a score of -2).
• E2: However unlikely this scenario might be, if Gustav turns out to be as bad or worse than Katrina, and the NOHPS fails to protect New Orleans, the immediate political outcome is unfavorable to the Republicans even if the event does not turn into a disaster.  But because Gustav did not result in a disaster, technically the situation is not as bad as E1.  Thus, I assess the political outcome from this scenario to be “-” (one minus, or a score of -1).
• E3: If Gustav turns out to produce a storm surge that is as bad or worse than Katrina, the fact that the NOHPS system protects New Orleans against a disaster stemming from flooding can be spun to mean that the Bush administration took the necessary steps to protect against hurricanes in the wake of Katrina.  The Republicans can (and will) play this up as a policy success.  Thus, I assess the political outcome from this scenario will be “++” (two pluses, or a score of +2).
• E4: If Gustav turns out to not be as bad as Katrina, yet the NOHPS fails to protect New Orleans against disaster, the Republicans should run and hide.  This situation can be spun as if the NOHPS, after several billion-dollars investment toward upgrades by the Bush Administration, is actually worse now than it was before Katrina (an arguable position, true, but one that seems likely to come from election opposition).  Thus, I assess the political outcome from this scenario will be “- -” (two minuses, or a score of -2).
• E5: If Gustav turns out to not be as bad as Katrina, yet the NOHPS fails to protect New Orleans, it really doesn’t matter what the outcome is (disaster or not).  This situation can be spun as if the NOHPS, after several billion-dollars investment toward upgrades by the Bush Administration, is actually worse now than it was before Katrina (an arguable position, true, but one that seems likely to come from election opposition).  But the discussion of whether New Orleans should be inhabited at all will likely rise to the forefront, and it is for me to credibly speculate on which party (or candidate) will offer the best (or most palatable) advice.  Thus, I assess the net political outcome from this scenario will not favor the Republicans, so I give it a “-” (one minus, or a score of -1).
• E6: If Gustav turns out to not be as bad as Katrina, and the NOHPS does its job successfully, then the Republicans can tout that they are doing a good job making progress toward a safer New Orleans.  While not nearly as strong as E3, the Republicans can, and probably will, squeeze out some brownie points for their effort.  Thus, I assess the political outcome from this scenario will be “+” (one plus, or a score of +1).
• E7: If Gustav does not appreciably affect New Orleans, then really there is nothing to worry about.  This does not mean that the topic of domestic preparedness will not come up during the remainder of the election season; rather, all I am claiming is that neither party can leverage Gustav to their benefit in any substantial way.  Thus, I assess the political outcome from this scenario to be “N” (neutral, or a score of 0).

With this consequence assessment in hand, the probabilities from the previous section can be used to construct a discrete probability distribution over the space of five political outcomes as shown below.  This figure communicates political risk, or rather, the uncertainty surrounding future political outcomes.  Again, ignore the apparent precision in the probability numbers – the interval actually makes them imprecise, but even so the digits past the decimal points are only a biproduct of arithmetic.  In the next section, you will see that the digits really don’t matter.

Summary of Results

Based on this assessment and without getting too detailed, we can arrange the three major outcomes in order of decreasing likeliness as follows:

• Neutral, or no affect [50%]
• Favorable political outcomes for the Republicans [~38%, 47.5%]
• Unfavorable political outcomes for the Republicans [2.5%, ~12%]

I think if I were the Republican campaign manager and I trusted this analysis, I would be excited and would be preparing myself with press statements and political advertisements aimed at bolstering the Republican candidate.  In contrast, if I were the Democratic campaign manager, I would start investing resources now in an effective press release aimed at mitigating the extent of any Republican political advantage following this event.

IMPORTANT CAVEAT: All things considered, and admitting that I am not learned in storm surge hydrodynamics nor do I fully appreciate the complexities of politics and political spin, I assign an overall analytic confidence of LOW (25% confidence, or a 67% chance that my analysis is valid).  Also, I am not saying what will happen one way or the other; rather my analysis just produced a subjective probability distribution over the space of potential political outcomes.  So, if a disaster does occur, my analysis is still not wrong.  After all, I never said disaster was impossible…

Afterthought

I could also do such an assessment from the Democrat point of view, but in this case the Republican’s loss is the Democrat’s gain (though admittedly the third parties may also absorb some of the benefit, so it is not quite a conceptual zero-sum game).  The conclusions would remain unchanged, however.

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ALERT: Hurricane Gustav is fast approaching the Gulf Coast.  According to the National Weather Service, National Hurricane Center, the center of this storm may make landfall Tuesday morning.   As of right this second (as reported via CNN Breaking News), the maximum sustained windspeed at some measured point in the storm system is 145 mph, thus making it a Category 4 storm according to the Saffir-Simpson hurricane intensity scale.  In terms of damage from wind and not including the effects of any ensuing storm surge, a category 4 storm can be qualitatively described as one that “produces more extensive curtainwall failures, with some complete roof structural failure on small residences. Heavy, irreparable damage and near complete destruction of gas station canopies and other wide span overhang type structures are also common. Mobile and manufactured homes are leveled. These hurricanes cause major erosion of beach areas and terrain may be flooded well inland as well” (as described on Wikipedia).

So, can we label Gustav as a natural peril?  What about as a natural hazard or natural disaster?  How can we classify Gustav right now?

A Comparison of Phrases for Bad Things

By its very nature, any tropical cyclone, hurricanes being a class of meterological events, is a natural peril.  According to the first few definitions that popup for the word “peril” on Answers.com, a peril is an “exposure to possible harm” or “something that endangers.”  Simply put, a peril is an event that can yield undesired outcomes to an individual or group of individuals exposed to its effects (whether to their person or their interests).  Irrespective of whether any particular hurricane afflicts some degree of harm on any particular individual, a hurricane is always a peril since its harmful agents (e.g., wind, water) are inherently damaging.  That is, whether or not a particular event is a peril depends on the characteristics of the event itself, and not of the individuals in its path.

In slight contrast, a “hazard” is a “possible source of danger” (also taken from Answers.com), where the word “possible” means that such an event can occur without indicating any degree of probability and the word danger indicates the event is an “instance of peril” (i.e., exposure in a specific context).  Whether or not an natural peril is also labeled as a natural hazard is a human-centric decision that depends on whether such an event can possibly afflict the individual charged with passing such judgment.  For example, in the eye of a New Orleans decision maker, a hurricane is, in fact, a natural hazard since past experience has proven such events to cause significant amounts of damage.  In contrast, a Mineapolis decision maker might not label hurricanes as a natural hazard in their decision space due to their infrequency in occurrence, and even if they did, the event would be of such low intensity that would make it indistinguishable from a routine thunderstorm.  Yet in both cases, a hurricane is still a natural peril.

At this point, I will restate that a natural peril is a naturally-occuring event whose characteristics would cause damage to an exposed asset, and a natural hazard is a naturally occuring event with the potential to cause harm to a particular individual.  Whether a naturally-occuring event is a peril depends on its objective characteristics, and whether it is a natural hazard depends on whether a particular individual is exposed to its effects and the individual’s subjective judgment of whether its effects are in fact damaging.  (bear in mind that I am using the word individual rather loosely, where it may be a single person or a person speaking on behalf of a number of people).

As with natural hazards, whether or not an event is a natural disaster is also in the eye of the person afflicted by the occurrence of such events.  The key difference between natural hazards and natural disasters is time – a natural disaster is typically a label assigned to a specific event that has actually caused “disastrous” damage (again, a subjective judgment), whereas a natural hazard is a label assigned to a event that has not yet afflicted the individual.

The Gustav Example

So let’s look at Hurricane Gustav from the point of view of a New Orleans decision maker (NODM).  As with any hurricane, by its very nature Gustav is a natural peril.  From the point of view of the NODM, Gustav is a natural hazard in that it is a possible source of danger to New Orleans given its current position and estimated trajectory.  In contrast, decision makers in Raleigh might not label Gustav a natural hazard since the chances are near-zero percent that its effects will afflict North Carolinan interests.  But can the NODM label Gustav as a natural disaster?  The answer is no, well, at least not yet.  Gustav has yet to afflict any damage, let alone damage of disastrous proportions on New Orleans.  Thus it is not (yet) a natural disaster from the NODM point of view.

But it is sensible to assign a probability to Gustav becoming a natural disaster based on the estimates of its trajectory and energy profile (from NWS) and the resistance of the New Orleans “system” to Gustav’s damage inducing effects.  In the particular example of New Orleans, the questions that will enable such an assessment is how high the ensuing storm surge at points along the hurricane protection system (i.e., levees, flood walls, and gates) will be (a function of storm position and intensity), the resistance of the HPS to the load imparted by the storm surge, whether the gates will actually be closed and whether the pumps will actually work, and what property and how many people are within the path of flood waters resulting from a breach.  Let me tell you, this is not an easy analysis (and I am speaking from experience having participated in the modeling and risk assessment of the New Orleans system as part of the Interagency Performance Evaluation Task Force, where I think my title was something like “Risk Modeler”).

Afterthought

Given where we are in time right now, I can’t help but speculate on the impact Gustav will have on the upcoming US presidential election.  Three outcomes are possible – Gustav will have no effect, Gustav will have a positive effect on the Republican platform (irrespective of candidate), or Gustav will have a negative effect on the Republican platform.  But at this point I wrote more than enough, and I defer this discussion to a later post.

Next up… Gustav and New Orleans: A Political Risk Assessment for the Republican Decision Maker.

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