I recently published a paper entitled “An Integrated Network Design and Scheduling Problem for Network Recovery and Emergency Response” in Operations Research Perspectives (volume 5, p. 218 – 231) with my PhD student Suzan Afacan Iloglu.

This paper studies a problem in post-disaster response and restoration. Disasters cause damage to important infrastructure systems such as power, water, and road infrastructure. We were particularly motivated by hurricanes, where the debris on roads after the storm make many roads impassable, which can greatly reduce the connectivity of the road network and substantially increase travel times. Often, teams of repair crews clear the roads before utility crews can come in and restore essential services. Given my experience studying emergency medical services, I was particularly interested in how emergency responders can efficiently deliver aid while the debris is being cleared.

In this paper, we seek to coordinate the activities of two types of service providers: (1) emergency responders who provide essential services and (2) repair crews who install arcs over a finite time horizon. We formulate the problem as a location and scheduling model, where emergency responders are located on a network. These facilities can be re-located over a time horizon while network components (arcs) are installed (the scheduling component). The results shed light on how to prioritize the restoration of damaged road infrastructure to assist in providing emergency aid after a disaster. The solutions indicate how to coordinate the recovery of road infrastructure by taking into account emergency service efforts, which is crucial to save more lives and improve resilience.

I had the pleasure of serving on a National Academies committee the past two years. Our report entitled “Tying flood insurance to flood risk for low-lying structures in the floodplain” was just released [Link].

If you don’t know much about the National Academies, it is a private, independent, nonprofit institution that provides technical expertise to important societal problems (engineering, in my case). The National Academies committees like the one I participated in address a specific challenge and has a very specific charge. The committee is composed of a bunch of really smart people who work together to answer the questions posed in the charge. FEMA provided the charge for my committee.

The specific charge is below, but a bit of background is necessary to know why the problem is so important and was it had to be addressed now. Recently, I blogged about floods and their huge impact on society [Link]. After a series of hurricanes that caused extensive flood damage to properties, the National Flood Insurance Program (NFIP) was created (in 1968) to reduce the risk of flood and mitigate flood damage by encouraging better flood management and building practices. The idea was that homeowners in flood-prone areas (“Special Flood Hazard Areas” – areas with an annual chance of flooding of 1% or more) would have to pay for flood insurance to help pay for the cost of disasters. Today, most homeowners in Special Flood Hazard Areas pay the going rate based on an elaborate formula set by FEMA. There are currently about 5.5 million flood insurance policies.

Those houses that already existed in a Special Flood Hazard Area in 1968 could be grandfathered into the program and receive subsidized rates. Over time, the hope was that these existing houses in Special Flood Hazard Areas would be replaced, thus reducing exposure in flood-prone areas. But they were not. They continue to exist and are expensive for FEMA when disasters strike. This is a huge problem. FEMA’s insurance premium formula as well as risk-based actuarial rates are incredibly sensitive to the elevation of the home relative to base flood elevation. These homeowners may pay $200 for a flood insurance premium per year when a risk-based actuarial rate may thousands of dollars. These houses are negatively elevated, meaning that they are below base flood elevation and flood frequently. There are a lot of these structures out there and they are costly to FEMA.

The Biggert-Waters (BW) Flood Insurance Reform Act of 2012 required these subsidized policies to disappear overnight, turning this important problem into an immediate problem. Subsequent legislation changed some of this, but the bottom line was that subsidized rates would rise, substantially for some. FEMA wanted a review of how they set their rates to be credible, fair, and transparent. That is where the committee came in.

Here is our study charge set by FEMA. In our conversations with FEMA actuaries, FEMA asked for shorter-term (within 5 years) and longer-term recommendations for improving their methods. FEMA asked us to look at how premiums are set and how the process could be improved. We focused on the math; another committee addressed the societal impact of the changes.

Study Charge
An ad hoc committee will conduct a study of pricing negatively elevated structures in the National
Flood Insurance Program. Specifically, the committee will:

1. Review current NFIP methods for calculating risk-based premiums for negatively elevated structures, including risk analysis, flood maps, and engineering data.
2. Evaluate alternative approaches for calculating “full risk-based premiums” for negatively elevated structures, considering current actuarial principles and standards.
3. Discuss engineering, hydrologic, and property assessment data and analytical needs associated with fully implementing full risk-based premiums for negatively elevated structures.
4. Discuss approaches for keeping these engineering, hydrologic, or property assessment dataupdated to maintain full risk-based rates for negatively elevated structures.
5. Discuss feasibility, implementation, and cost of underwriting risk-based premiums for negatively elevated structures, including a comparison of factors used to set risk-based premiums.

We constructed ten conclusions:

1. Careful representation of frequent floods in the NFIP water surface elevation–probability functions (PELV curves) is important for assessing losses for negatively elevated structures.
2. Averaging the average annual loss over a large set of PELV curves leads to rate classes that encompass high variability in flood hazard for negatively elevated structures, and thus the premiums charged are too high for some policyholders and too low for
   others.
3. NFIP claims data for a given depth of flooding are highly variable, suggesting that inundation depth is not the only driver of damage to structures or that the quality of the economic damage and inundation depth reports that support the insurance claims is poor.
4. When the sample of claims data is small, the NFIP credibility weighting scheme assumes that U.S. Army Corps of Engineers damage estimates are better than NFIP claims data, which has not been proven.
5. Levees may reduce the flood risk for negatively elevated structures, even if they do not meet NFIP standards for protection against the 1 percent annual chance exceedance flood.
6. When risk-based rates for negatively elevated structures are implemented, premiums are likely to be higher than they are today, creating perverse incentives for policyholders to purchase too little or no insurance. As a result, the concept of recovering loss through pooling premiums breaks down, and the NFIP may not collect enough premiums to cover losses and underinsured policyholders may have inadequate financial protection.
7. Adjustments in deductible discounts could help reduce the high risk-based premiums expected for negatively elevated structures.
8. Modern technologies, including analysis tools and improved data collection and management capabilities, enable the development and use of comprehensive risk assessment methods, which could improve NFIP estimates of flood loss.
9. Risk-based rating for negatively elevated structures requires, at a minimum, structure elevation data, water surface elevations for frequent flood events, and new information on structure characteristics to support the assessment of structure damage and flood risk.
10. The lack of uniformity and control over the methods used to determine structure replacement cost values and the insufficient quality control of NFIP claims data undermine the accuracy of NFIP flood loss estimates and premium adjustments.

You can read more about our report and its conclusions in the press release.

The committee was composed of 12 members and included civil engineers, risk analysts, actuaries, and one retired FEMA employee. Our fearless chair David Ford did a lot of the heavy lifting in terms of crafting our core conclusions. National Academies staff member Anne Linn was incredibly helpful in terms of getting us focused, staying on track, and writing the report. National Academies staff member Anita Hall did the logistics and was incredibly responsive to our travel needs. The committee met in person four times and wrote parts of the report. The report was sent out to reviewers, and we changed parts of the report in response to reviewer comments much like in a peer-reviewed journal. We couldn’t have done this without David and Anne (many thanks!)

Serving on the committee helped me understand the importance of flooding from many possible perspective. I bought a new house during the my time on the committee. My new house is on the top of a ridge with virtually no chance of flooding.

Serving on the committee also helped me to learn about state-of-the-art techniques in civil engineering and risk-based insurance. Our colleagues in other fields do some pretty cool things, and we can all work together to make the world a better place. I’m proud of our final report – I hope it leads to more credible, fair, and transparent NFIP flood insurance premiums.

This week’s flooding in Texas highlights how vulnerable we are to flood risks. Texas is extremely prone to flooding yet is among the worst states when it comes to flood-control spending. Texas is exposed to significant riverine flooding in addition to storm surge flooding caused by hurricanes and tropical storms. Texas has the second most flood insurance premiums in the US (second only to Florida).

In the past year, I have been serving on a National Academies committee on flood insurance for negatively elevated structures. I have learned a lot about flood insurance, incentives, and risk. I can’t say anything about the report yet except that it will be released soon, but I can tell you a little about the problem and how management science has helped us understand how to mitigate flood risks.

Floods occur frequently (although not frequently enough to motivate people to mitigate against the risks) and when floods occur, they do a lot of damage. The damage is usually measured in terms of structure and property damage, but flooding also leads to loss of life and injuries. Flooding is not just a coastal issue – floods occur along rivers, in areas with high water tables, and in urban areas where infrastructure channels water in such a way that it creates flood risks. Cook County, Illinois has chronic urban flooding issues that is expensive. Floods lead to enormous socioeconomic costs. Two-thirds of Presidential disaster declarations involve floods.

The basic approach to managing flood risks is to (1) encourage people not to build in floodplains and (2) building less flood-prone structures and communities to reduce the damage when floods occur. Getting this to happen is tough. Improving infrastructure requires an enormous investment cost either to society (e.g., flood walls), communities (e.g., FEMA’s Community Rating System), or individuals (e.g., elevating a house). A Citylab article criticizes Texas for not investing in infrastructure that could reduce the impact of floods.

On an individual level, flood insurance is required for those who live in “Special Flood Hazard Areas” (a floodplain; FEMA defines a “Special Flood Hazard Area” as an area with a >1% annual chance of flooding). Flood insurance can be really expensive, which can encourage individual homeowners to either forego insurance or mitigate against flooding. Elevating a house is expensive, but it may be a good financial choice if it reduces flood insurance by thousands of dollars per year. The reality is that most homeowners do not have a flood insurance policy even when it is required because insurance is expensive and is perceived as not needed. Many homeowners in floodplains go decades between floods, and despite the warnings and requirements, they do not see the need to pay so much for flood insurance when they have not experienced a flood.

I recommend reading Catherine Tinsley and Robin Dillon-Merrill’s paper on “near miss” events in Management Science and their follow-up paper with Matthew Cronin. Their papers demonstrate that when someone survives an event like a natural disaster that was not fatal or too traumatic (e.g., a flood that didn’t do too much/any damage), they are likely to make riskier decisions in the future (e.g., they cancel their flood insurance).

A Wharton report by Jeffrey Czajkowski, Howard Kunreuther and Erwann Michel-Kerjan entitled “A Methodological Approach for Pricing Flood Insurance and Evaluating Loss Reduction Measures: Application to Texas” specifically analyzed flood loss reduction methods in Texas. They recommend supplementing the flood insurance with private flood insurance (FEMA currently provides homeowners with flood insurance through the National Flood Insurance Program) to encourage more homeowners to purchase insurance. They also evaluate the impact of elevating structures in the most flood-prone areas, and they find that mitigation through elevation can be instrumental in reducing much of the damage.

What have you experienced with flooding?

The devastating tornadoes in Oklahoma and Arkansas this weekend was a sad way to start tornado season. Sensing equipment and forecasting models have been used in improved advanced warning systems to help people take shelter, however, major tornadoes are still pretty deadly. The recent 2011 tornado in Joplin, MO was one of the deadliest ever. The  “Weather Forecasting Improvement Act of 2014,″ which passed the House in April 2014, seeks to address this need.

While there is room for improvement when it comes to advanced tornado warnings, the cost associated with the warning systems is somewhat controversial. Federal funding for disasters is essentially a zero-sum game, so high-profile disasters like tornadoes can use up a disproportionately high amount of the budget allocated to disaster research, leaving us vulnerable to other less news-worthy disasters. Since there are so few tornado-related fatalities every year compared to other weather disaster (e.g., heat waves), there isn’t much of a potential to save lives regardless of how good the advanced warning system becomes.

Meteorologist Eric Holthaus wrote a nice article on Slate about this issue [Link]

While it’s necessary to continue making progress on hurricane and tornado forecasts, it should definitely not be at the expense of funding to improve forecasts of lower-profile weather and climate disasters that, in aggregate, kill dozens of times more people per year, and are increasing. Essentially, the bill invests scarce funds in high-profile weather events at the expense of those that cause many more deaths. Boosted by human-caused climate change, heat waves now kill more people in the United States each year than hurricanes, tornadoes, lightning and floods combined, according to the CDC. And weather-related traffic accidents kill 10 times more than heat waves—more than 6,000 people per year. [see the first image below to visualize these magnitudes]

Track the bill here. The bill focuses on forecasting, but I am going to take this a step further and examine the entire warning system to see if there are other ways we could save lives. The ultimate goal is to keep people safe, and there are many ways to do so. I grew up with tornado sirens, which were great so long as you were awake. I was surprised to learn that this is generally the (see the bottom figure below). TV warnings are another old-fashioned way to warn people, which seemed to work back in the era when people watched network TV. Virginia does not have too many tornado sirens (although it had tornadoes!), and since I do not watch much TV, my family missed a couple of warnings. Later, Virginia Commonwealth University used the campus siren installed to warn us of active shooters on campus as a makeshift tornado alarm. In my opinion, that was terrific. They have had more tornadoes than shootings.

I later learned that I could get the best warnings from following meteorologists and weather nerds on twitter. I highly recommend following nearby National Weather Service offices on twitter to get high quality information in real-time (get started here). Weather apps can deliver warnings even if you aren’t actively using the app. I think these are all great options, but I am still sometimes blissfully unaware of serious weather despite being “prepared.” Being able to reach everyone including those who cannot be reached by the most far-reaching alerts in our shifting technology landscape is not a forecasting problem (e.g., the deaf cannot hear sirens). The point is that there are some serious challenges in ensuring that the warnings get to the people quickly. Doing so isn’t so much of a forecasting problem, unless the forecasts give much, much earlier warnings (think: hours instead of minutes).

Another problem is that I can always choose to ignore the warnings even if I get them. This will likely happen if there are too many weather warnings/false alarms (The Weather App That Cried Wolf). I blogged about this issue here.

The OR tie in for this post may be somewhat dubious, but the connection here is that these issues cut to systems thinking and tradeoffs. Plus, I’m a daughter of the Midwest and will always be somewhat obsessed with weather and tornadoes. Your thoughts on optimal ways to keep people safe (broadly speaking) from tornadoes are welcome.

From “Investing More Money in Tornado Research Would Be a Disaster” by meteorologist Eric Holthaus. Click through for more information.

Related factoid: most of the world is not at an increased risk of tornadoes. So tornado prediction and preparedness is mostly a United States problem

Parts of the world at an increased risk of tornadoes are in red. Courtesy of NOAA. Click through for more info.

Another factoid: tornadoes are far more likely to occur in the late afternoon and early evening than overnight. I was shocked to learn this.

Tornado likelihood across the United States. Click through for more information.

Related posts:

• What is the optimal false alarm rate for tornado warnings?
• Italian scientists convicted of manslaughter for making a Type II error with respect to a disaster warning