XClose

UCL Earth Sciences

Home
Menu

MSc Geophysical Hazards: Vulnerability to Meteorological Hazards

Spotlights:Social vulnerability; Hazard exposure and resilience; Natural disasters; Meteorological hazards.

As part of the coursework requirements for the MSc Geophysical Hazards and Postgraduate Certificate Natural Hazards for Insurers programmes, students were asked to write articles in the style of an online blog on the topic of vulnerability to meteorological hazards. To learn more about social vulnerability to tornadoes in the United States, or reducing the impact of hurricanes in the Caribbean, check out some of the student blogs here.

Vulnerability to wildfire in California


VULNERABILITY TO WILDFIRE IN CALIFORNIA BY INDIA RINGER

In many ways wildfire disasters can be viewed as indiscriminate, hitting all communities in their path, and the economic cost of these fires is astronomical.

Resilience to hurricanes in the Caribbean 
 
In the Shadow of the USA: Improving Resilience to Hurricanes in the Caribbean  By Alec Godsland

Education of the consequences of historical hurricanes provides populations with the skills to construct evacuation and damage mitigation plans.

 How vulnerability can turn hazards into disasters
 
Tornadoes in the United States: How social vulnerability can turn a hazard into a disaster  By Phil Kreußler

Tornadoes have always fascinated mankind. They can form in the blink of an eye and leave a trail of devastation in no time at all.

Wildfire vulnerability in the USA
 

Wildfire Vulnerability in the USA By Inês de Araujo Muggli
Wildfire management and the factors influencing social vulnerability must be explored together in order to create more resilient communities.”

 Vulnerability of California to drought

 
MSc Geohazards Blog 5
Whilst droughts in California pose a severe threat to the entire region, their impacts are felt disproportionately amongst the state’s population.

 The Vulnerability of New Orleans

 
MSc Geohazards Blog  The Vulnerability of New Orleans
A future event on par with Hurricane Katrina is likely, yet New Orleans remains vulnerable and unprepared for such events despite its devastating history.

 


Vulnerability to wildfire in California

by India Ringer

The severity of wildfires in California has greatly ramped up in recent years. This shift has been linked to climate change, whether this is the case or not we have certainly seen temperatures increase and the land become drier and more prone to damaging wildfire. There are fire records in California going back to 1932; of the 10 largest fires since then, nine have occurred since 2000, five since 2010 and two in 2018 [1].

Wildfire in Southern California. Source: Image by Kevin Key
Image Caption: Wildfire in Southern California. Source: Image by Kevin Key.

The economic cost of these fires is astronomical; it’s estimated the clean-up cost of the 2018 November fires is $3 billion [2], and according to Munich Re the 15 major fires in 2018 combined cost US insurance companies $25 billion [3]. The devastating Camp Fire caused more deaths than any previous wildfire in the state. It moved at a rapid pace, burning around 80 acres per minute [4]. The Mendocino Complex Fire in July 2018 ravaged nearly 460,000 acres, surpassing the record set by 2017’s Thomas Fire [5].

In many ways these disasters can be viewed as indiscriminate, hitting all communities in their path. You only have to look at those impacted by the 2018 fires to see that these catastrophes strike across the entire state, from Northern to Southern California, and that even well-built properties cannot withstand the damage wildfire can cause. However, arguably certain areas and communities are in fact more vulnerable than others. Cities in “wildland–urban interface zones” [6] are particularly vulnerable. These are areas where houses and other structures interweave with woodland and vegetation and thus are especially prone to wildfire. Climate change is not the only factor increasing the severity of these fires, urbanisation is also having an impact. WUI areas have expanded greatly in the last 50 years, with communities moving further into forest areas. The areas hit by the Camp Fire in 2018 and the Tubbs Fire in 2017 had not previously experienced these vast and devastating fires. However, neighbourhoods and cities have greatly expanded into these areas so there has increasing amounts of infrastructure in harm’s way.

Additionally, it has been found that some communities are more vulnerable to the impact of wildfires than others. It has been shown that wildfires disproportionately affect the poor and ethnic minorities [7]. A clear example of this can be seen through the socio-economic differences between wildfire areas such as Woolsey and Camp in 2018. This demonstrates the disproportionate impact of those impacted.

 

Maps which demonstrate the different communities impacted by the 2018 wildfires. Source: Image by Leah Squires for Direct Relief

Figure Caption: Maps which demonstrate the different communities impacted by the 2018 wildfires. Source: Image by Leah Squires for Direct Relief.


14% of the population within the Camp Fire perimeter live below the poverty line. This is more than double the Woolsey perimeter [7]. Low income families are less likely to have adequate insurance and thus many former Paradise residents may not be able to afford rebuilding costs.  Moreover, those living in rural areas, low-income neighbourhoods, and immigrant communities are much less likely to be able to invest in fire safety which increases their vulnerability to wildfire. The impact of these inequalities can be seen after the 2017 fires in Sonoma County, California, where price gouging on rental properties heightened an already critical housing shortage [8].

Ethnic minorities are also particularly affected by wildfires. A study found that Native Americans can be hugely impacted and are in fact 6 times more vulnerable to the effects of wildfire than white people. Black and Hispanic people are about 50% more vulnerable [7]. This is in part due to the fact that the reservations tend to be located on grassland or close to woodlands, thus are more prone to wildfire. Century-old rules made it illegal to set fire to public forest land which ultimately prevented tribes from reducing the wildfire risk through controlled burns. In recent years federal agencies have engaged with tribes to carry out controlled burns in an attempt to mitigate against the risk.

 

The destruction caused by the Sonoma & Napa Valley Wildfires in October 2017. Source: Image by Janos.

Image Caption: The destruction caused by the Sonoma & Napa Valley Wildfires in October 2017. Source: Image by Janos.

Other elements include access to a car which is clearly fundamental for evacuations, and whether individuals are fluent in English. In 2017, as three fires tore across Napa, most emergency messages were communicated in English despite 30% of Napa’s population being Hispanic [9]. These socioeconomic factors have been described as “adaptive capacity.” They are elements that make individuals more vulnerable and also with a lesser ability to cope and adapt if a disaster occurred. Dr. Bolin states that “the difference between the wealthy and the poor is the wealthy can afford losses, they have insurance, health insurance, secure jobs (typically somewhere else) and the poor don’t” [10].

“Communities that are majority black, Hispanic or Native American are over 50 percent more vulnerable to wildfire” -P. LEVIN (2018)

Overall, we can see that wildfire provides another example of how the kinds of disasters exacerbated by climate change often impact the poor and ethnic minorities the most. It’s been suggested that as global warming continues that the severity of wildfire is likely to increase. Thus its crucial to identify areas which are particularly vulnerable and may need support or funding. As Rachel Morello-Frosch, a professor at the University of California, Berkeley argues, research can “enhance the resilience of fire-prone communities, particularly for communities of color that are often overlooked when these disasters happen” [11].

References
[1] New York Times: Why Does California Have So Many Wildfires? (2018).
[2] Bustle: The Cost Of California Wildfire Damage In 2018 Is Astronomical — And It Could Keep Climbing (2018).
[3] Los Angeles Times: California’s Camp fire was the costliest global disaster last year, insurance report shows (2019).
[4] Wired: The Terrifying Science Behind California’s Massive Camp Fire (2018).
[5] Business Insider: New wildfire tears through drought-stricken forest as California reels from its biggest fire in state history (2018).
[6] RSG!: Wildland Urban Interface.
[7] I. Davies, R. Haugo, J. Robertson, P. Levin: The unequal vulnerability of communities of color to wildfire (2018).
[8] The New York Times: California Today: Price Gouging Complaints After the Wildfires (2017).
[9] PRI: Many Latinos are struggling in California's wildfires, but Spanish-language information is scarce (2017).
[10] NY Times: Minorities Are Most Vulnerable When Wildfires Strike in U.S. Study Finds (2018).

Further Reading
1. Direct Relief: California Wildfires: Mapping Social Vulnerability (2018).


Back to top


In the shadow of the USA: Improving resilience to hurricanes in the Caribbean
By Alec Godsland

Vulnerability is a concept that encompasses a variety of definitions. Independent of the severity and frequency of the hazard, it is the susceptibility of a population to experience damage, injury or economic loss due to that hazard. An essential point is that vulnerability to a particular hazard varies on an intra-locational and inter-locational basis due to the intrinsic socio-economic and geographic factors. Hurricanes display this variance particularly well, as their paths often encompass several countries, highlighting the resilience – or lack of – that different populations have to this meteorological hazard. The 2017 hurricane season was an exceptional year in the North Atlantic, breaking several records for frequency and severity of major hurricanes. This sequence, as well as previous occurrences, have shown the disparity in vulnerabilities between the Caribbean nations and the USA.

Financial Barriers
A community’s ability to reduce their vulnerability through preparation before, and recovery from, natural disasters is constrained by its financial power. Whether this is achieved through its own investment or insurance, this desired resilience requires significant capital. High levels of debt and dependence on fossil fuel imports are major impediments for Caribbean nations in achieving resilient and sustainable development. These economies lack the fiscal space to invest in risk management, but there are proven solutions to this issue. Barbados has partially alleviated its reliance on fossil fuels by offering tax benefits for the production and installation of solar water heaters [1]. Explanation of these resilience techniques to the public and investors could produce further resilience dividends, such as reduced insurance premiums.

The 2017 hurricane season was devastating to many regions that house extensive seagrass meadows, including Turks and Caicos, Puerto Rico, Cuba, the British Virgin Islands and Florida. In particular, the Turks and Caicos Islands’ lack of fertile soil makes them highly dependent on imported goods. The seagrass meadows surrounding the island are vital for marine wildlife, which underpins their main export sectors – fishing and tourism [2]. The seagrass is a habitat for marine species farmed for hotels and those species that attract marine tourism. As they move over these marine ecosystems, hurricanes rip up the flora and fauna from the seafloor, leaving the water columns full of suspended sediments that reduces growth and recovery by blocking sunlight. Whilst Florida also felt these physical effects from Irma in 2017, the dependency on this food source is far less significant as in the Caribbean [3].

Devastation to areas of the Florida Keys (left) and St. Martin (right) by Hurricane Irma is comparable. However, the reactive resilience response is not [4]. Sources: United States Air Force and Netherlands Ministry of Defence, respectively.

Image Caption: Devastation to areas of the Florida Keys (left) and St. Martin (right) by Hurricane Irma is comparable. However, the reactive resilience response is not [4]. Sources: United States Air Force and Netherlands Ministry of Defence, respectively.

 

Beachfront Bombardment
Hurricanes pose a threat through a number of different hazards, but in each case, vulnerability is greatest on the coast. The low-pressure centre combined with the force of the hurricane’s winds can drive seawater onto the coast. In some cases, these storm surges can reach heights of 8m (Katrina, 2005). Low-lying coastal areas are inherently vulnerable to storm surge. For example, Anguilla, Antigua & Barbuda, Dominica, St. Kitts & Nevis, Turks & Caicos, and Netherlands Antilles will be inundated with a 3m sea level rise. Similarly, it has been estimated that 20% of the population in the Bahamas, Belize and Guadeloupe would be affected by a 6m sea level rise [5].

Likewise, the coastline of the USA is vulnerable to storm surge, notably in Louisiana, Florida, Georgia and the Carolinas. Unlike the Caribbean nations, however, the USA has the financial power to protect the most vulnerable areas. This is exhibited in New Orleans, where construction began in 1965 on a vast series of levees inspired by the flooding concerns induced by Hurricane Betsy of that year. Despite the investment and foresight, the levees were only 60-90% complete by the time Hurricane Katrina struck [6]. Catastrophic failure ensued, with flooding of 80% of New Orleans, including all of St. Bernard Parish – one of the most vulnerable areas.

In response to Hurricane Katrina and the disastrous performance of the levees, two new floodgate structures have been built – the Lake Borgne Surge Barrier and the Seabrook Floodgate. These have been constructed to reduce the susceptibility to storm surge of the most vulnerable regions, including St. Bernard Parish. The combined costs of these floodgates almost surpasses USD 900m [7] – far above the resources available to any Caribbean nation.

GDP of Caribbean nations in 2017. GDP for Cayman Islands and U.S. Virgin Islands taken from last year available, 2006 and 2015 respectively. Source: World Bank.

Figure Caption:  GDP of Caribbean nations in 2017. GDP for Cayman Islands and U.S. Virgin Islands taken from last year available, 2006 and 2015 respectively. Source: World Bank.
 

Resilience through Regulations
Building regulations exist to ensure any newly constructed building is sufficiently resistant to many hazards, including wind. The wind load acting on the elevations should be absorbed safely and efficiently by the building structure in order to avoid collapse. Codes such as these are often ignored in the Caribbean, as the incentives to conform are negligible. Low-income regions cannot afford the high-quality building material required or construction expertise to oversee the development. On top of these restraints, there is the need to rebuild quickly – in time for the next impending hurricane season.

Adopting building codes is a major short-term cost, requiring expenses for materials and skilled labour. However, in the long term the cost benefits can be realised in reduced reconstruction costs and allowing economies of scale in production and building. This reduction in building vulnerability directly reduces the vulnerability of the residents, as well as indirectly by making access easier for first responders and emergency supplies. The benefit is seen in the USA where these codes are strictly enforced. A study by the IBHS after Hurricane Charley in 2004 calculated that the adoptive changes to the building code in response to Hurricane Andrew reduced the number of residential property claims by 60% and the cost of claims by 42% [8].

Knowledge is Power
A vital ingredient to reducing vulnerability to hurricanes is awareness of their occurrence. This is awareness of previous effects, as well as real-time information on incoming events. Education of the consequences of historical occurrences provides populations with the skills to construct evacuation and damage mitigation plans. Access to live hurricane information allows these plans to be adapted for the current situation.

Storm surge mapping is readily available for coasts of mainland USA, Puerto Rico and the U.S. Virgin Islands. This gives residents the ability to be proactive about their potential evacuation rather than needing to react once the situation occurs by which time it might be much more difficult to organise. This access to information is in stark contrast to some Caribbean nations. According to the Population and Housing Census Report in 2001, around 30% of residents of St. Vincent had access to satellite television, less than 15% owned a computer and less than 10% had access to the internet [9].

GDP of Caribbean nations in 2017. GDP for Cayman Islands and U.S. Virgin Islands taken from last year available, 2006 and 2015 respectively. Source: World Bank.

Image Caption: Storm surge vulnerability map for southern Florida. Indication of storm surge height above ground: blue - less than 3 feet; yellow - greater than 3 feet; orange - greater than 6 feet; red - greater than 9 feet. Source: The National Oceanic and Atmospheric Administration (NOAA).

Caribbean nations, haemorrhaged by continual destruction, and inundated with debt, are sailing into the wind in their attempts to build resilience to hurricanes. However, it is clear for all vulnerability comparisons that short-term investment can yield long-term gains economically. As a global population, disparities such as these must be acted on to help the most vulnerable prosper.

 

References

[1] Bugler, W. (2012). Seizing the sunshine: Barbados’ thriving solar water heater industry, CDKN Inside Story. London: Climate and Development Knowledge Network.

[2] Cullen-Unsworth et al. (2014). Seagrass meadows globally as a coupled social–ecological system: Implications for human wellbeing. Marine Pollution Bulletin, 83, 387-397.

[3] Djiofack, Calvin Zebaze; Velasquez, Giselle. 2015. Caribbean trade report: the new trade environment and opportunities for the poor in the Caribbean (Vol. 2): Trade matters: new opportunities for the Caribbean. Washington, D.C.: World Bank Group.

[4] FEMA (2017). News Release: Hurricane Irma Response and Relief Operations Continue with Full Federal Capability.

[5] Kam-Biu, Liu (2002). Hurricanes and coastal zone vulnerability in Central America and the Caribbean under a changing climate [PowerPoint presentation].

[6] Army Corps of Engineers (2005). Lake Pontchartrain and Vicinity Hurricane Protection Project. United States Government Accountability Office.

[7] Hillen, M.M. (2010). Coastal Defence Cost Estimates. Case Study of the Netherlands, New Orleans and Vietnam. The Netherlands: TU Delft.

[8] Insurance Institute for Business & Home Safety (2018). Rating the States: 2018: An Assessment of Residential Building Code and Enforcement Systems for Life Safety and Property Protection in Hurricane-Prone Regions.

[9] Caribbean Community (CARICOM) Secretariat National Statistical Office (2001). St. Vincent and the Grenadines - Population and Housing Census 2001.

 

Further Reading

1. Emily Wilkinson (2018). Towards a more resilient Caribbean after the 2017 hurricanes. [Conference Report]. Overseas Development Institute.

Back to top


Tornadoes in the United States: How social vulnerability can turn a hazard into a disaster

By Phil Kreußler

If you were living in the United States and if you were to hear a tornado siren going off right now, what would you do? Surely, like most other people, you would try to avoid the tornado and to seek shelter as quickly as possible. But would you have ever asked yourself why you might be at greater risk than others, say your children, neighbour or postman? Probably not, but it is definitely worth doing because fatalities related to tornadoes show significant tendencies towards certain lifestyles.

More than Only Hot Air
Tornadoes have always fascinated mankind. They can form in the blink of an eye and leave a trail of devastation in no time. Basically, they are nothing more than spinning columns of air, but they can reach windspeeds of up to hundreds of kilometres per hour and cause severe damage to life and property. They form in big thunderstorms where uprising warm and moist air is set into rotation. If the created cloud funnel connects with the ground, a tornado is born. The US are the region most prone to tornado formation with over 1200 events in the last decade [1], simply because the environmental conditions are so favourable.

The deadliest tornado incidence happened in 1925, when the so-called tri-state tornado caused almost 700 fatalities in the states of Missouri, Illinois and Indiana [2]. Unfortunately, 9 schools were destroyed and nearly 70 students killed [3]. This disaster raises the question if there is more to the danger of a tornado than its physical properties like size and intensity only, if there are other factors which can influence the likelihood of being affected by a storm.

Left: Typical thunderstorm that spawns a tornado. The distinct cloud funnel extends to the surface and exhibits extreme windspeeds. Photo by Nikolas Noonan on Unsplash. Right: Damage that portrays the destruction left behind in Illinois after the 1925 tri

Image caption: Left: Typical thunderstorm that spawns a tornado. The distinct cloud funnel extends to the surface and exhibits extreme windspeeds. Photo by Nikolas Noonan on Unsplash.
Right: Damage that portrays the destruction left behind in Illinois after the 1925 tri-state tornado. Photo courtesy: Jackson County Historical Society, Murphysboro, Illinois on Wikimedia.

Social Vulnerability: A Complex Measure
The answer is: Yes, there is more, much more! Social vulnerability is the concept that tries to describe the degree to which a population is susceptible to harm, injury or damage by a hazard. It focuses on life conditions and preparedness rather than on the physical impact of the hazard: For example, someone without access to transportation is more vulnerable to being affected by a hazard simply due to their lack of mobility in case of evacuation. Applying this concept to the tornado hazard in the US identifies four main components of social vulnerability: the population itself, their organisation, their living environment and their access to technology [4].

Studying the influence of a population’s characteristics reveals a few key points. Unsurprisingly, the age plays an important role. Considering the ability to move and seek shelter, the very young (under 10) are at greater risk [5] but also the middle-aged and elderly (over 40) are more vulnerable, showing a higher percentage of fatalities than their younger counterparts [6]. Conversely, there does not seem to be any major difference between the sexes: About 48% of all tornado victims are male, while roughly 44% are female. This lack of difference makes the tornado hazard unique compared with other thunderstorm-related hazards where usually a clear trend towards one of the sexes can be found [6].

Organising this population or group can also have an effect on vulnerability. A single person is much more flexible and can adapt to emergency situations more easily than a household of four or five. The more members a group has, the more effort is required to communicate warning and response effectively. Especially, significant relationships between family members and friends influence the time needed for protective action which cuts into the amount of time the group has to protect itself [4] because nobody wants to leave grandfather or the family pet behind.

But not only a population’s age and size matter, their living environment does so, too. With more and more people moving to cities, these areas become increasingly urbanised whereas rural regions become less so. Intuitively, you would expect that this would decrease urban vulnerability, but yet the opposite is the case: people living in rural areas often are more closely connected to nature and more aware of precursors to a hazard. Further, the lack of occurrence of tornadoes in big cities leads to a decay in preparedness and thus increases vulnerability [4]. A person’s mindset can also influence their coping-style, specifically persons from southern and Midwest US are more vulnerable due to their tendency for fatalism, passivity and lack of trust in warning systems [7].

Although these aspects largely contribute to tornado vulnerability, they are outweighed by the importance of technology, meaning the standard of housing in particular. In the US, so-called mobile homes (trailers, caravans) are widely used as permanent residences. Due to their focus on mobility they lack structural robustness and are vulnerable to high winds and less capable of resisting tornadoes. The numbers prove that mobile homes are not suitable as tornado shelter: An incredible 6% increase in fatalities is to be expected with every 1% increase in mobile homes [4]. Very frequently, a connection between the number of mobile homes and a population’s income is drawn. And indeed, it is plausible that people with low income tend to live in insecure shelters due to the lack of means to afford sustainable housing [4]. Unfortunately, this fact does not only apply to the tornado hazard but in general, people with less financial power and living in poor conditions are those who are most vulnerable to any natural hazard.

Left: Example for a mobile home. These are highly vulnerable to tornadic wind damage. Photo by Angelo Pantazis on Unsplash. Right: Concept of social vulnerability to tornadic hazards in the US.

Image caption: Left: Example for a mobile home. These are highly vulnerable to tornadic wind damage. Photo by Angelo Pantazis on Unsplash. Right: Concept of social vulnerability to tornadic hazards in the US.

Change is the Only Constant, Let’s be Prepared!
The interplay of these components shows that a tornado hazard can be turned into a true disaster if the right (wrong) combination of circumstances is given and if a particularly vulnerable group of people like children is exposed to the event (remember tri-state tornado!). Although we understand this concept, we still experience significant loss of life from tornadic events like in 2011, when over 300 fatalities were reported following a major tornado outbreak. Ideas to improve the approach of social vulnerability include using a more complete database and considering as many demographic indicators as possible [5].

In addition to that, we should prepare for future challenges like demographic changes or climate change. It is very likely that a changing climate will impact the nature of tornadoes. Further research and more data will be required to answer these questions. In the meantime, we all should try to remain as young as possible and to live on our own, in a non-mobile home far away from the city.  

   

References

[1] "U.S. Tornado Climatology | National Centers for Environmental Information (NCEI) formerly known as National Climatic Data Center (NCDC)".www.ncdc.noaa.gov. Retrieved 2016-04-20.

[2] Gibson, Christine (Aug–Sep 2006). "Our 10 Greatest Natural Disasters". American Heritage. 57 (4).

[3] Grazulis, Thomas P. (July 1993). Significant Tornadoes 1680-1991: A Chronology and Analysis of Events. St. Johnsbury, VT: The Tornado Project of Environmental Films.

[4] Donner, W. R. (2007). The political ecology of disaster: An analysis of factors influencing US tornado fatalities and injuries, 1998–2000. Demography, 44(3), 669-685.

[5] Kuster, C., & Ripberger, J. (2019). Examining Vulnerability to Tornadoes Using Census Tract-Level Demographic Data and Tornado Damage Survey Paths.

[6] Ashley, W. S. (2007). Spatial and temporal analysis of tornado fatalities in the United States: 1880–2005. Weather and Forecasting, 22(6), 1214-1228.

[7] Sims, J. H., & Baumann, D. D. (1972). The tornado threat: Coping styles of the North and South. Science, 176(4042), 1386-1392.

Back to top


Wildfire vulnerability in the USA
By Inês de Araujo Muggli

Natural disasters affect billions of people worldwide, with minority and poorer communities being more vulnerable to their impacts than more affluent demographics. Over the last decade, wildfires have ravaged forests around the world causing significant damage. In the U.S., approximately 29 million Americans live in areas with high wildfire risk of which 12 million are particularly vulnerable [1]. The spread of this particularly vulnerable population is not equal across race or ethnicity, with Black, Hispanic or Native American demographics around 50% more vulnerable to wildfires than white Americans [2]. Taking vulnerability of population into consideration with wildfire occurrence when managing fire-prone landscapes could help identify areas poorly equipped to respond to wildfires in the hopes of mitigating any impacts of wildfire events. Such measures could determine whether the wildfire hazard becomes a devastating wildfire disaster.

 

of the Camp Fire on Nov. 8 from the Landsat 8 satellite. This was the deadliest wildfire in California’s history with 71 fatalities. Source: Image from USGS/NASA/Joshua Stevens.

Image caption: The Camp Fire on Nov. 8 from the Landsat 8 satellite. This was the deadliest wildfire in California’s history with 71 fatalities. Source: Image from USGS/NASA/Joshua Stevens.

 

From a Hazard to a Disaster
Previous natural disasters in the U.S. have shown how lower-income communities can be devastatingly more vulnerable to events than more affluent populations. When Hurricane Katrina hit New Orleans in 2005, the less affluent African American community had a disproportionate amount of fatalities and property damage compared to other ethnicities. For example, 84% of missing people were African American when only 68% of New Orleans population is Black [3]. This was largely due to the fact that they did not have the means to evacuate before the hurricane struck. It is argued that it is not the hazard that is the “natural disaster” but it is the social, political and economic context i.e. the vulnerability of a population, that turns a hazard into a disaster. This was clearly the case during Hurricane Katrina and following hurricanes which have since struck, where differences in vulnerability affected the magnitude and duration of the hurricane hazard impacts e.g. loss of property and life.

Extensive damage in New Orleans following Hurricane Katrina. African American communities were the worst affected.

Image caption: Extensive damage in New Orleans following Hurricane Katrina. African American communities were the worst affected. Source: Image from The White House Archives

 

Applying this to Wildfires
In the U.S. wildfires have had an increasing occurrence over the last few years, with California experiencing some of the deadliest and most costly forest fires in history. Mitigation strategies include tree trimming and bush removal which can create significant costs to households. Such simple measures can mean the difference between a low-severity underburn and a severe wildfire [4]. The quality of materials used to build housing also influences vulnerability with cheaper materials such as wood being much more flammable than cement. Furthermore, household renters are not eligible for federal assistance to rebuild their homes after a fire so are often left homeless [5]. Like in hurricane Katrina, less affluent populations do not have access to evacuation measures such as immediate transport nor mitigation measures such as home insurance. These are just some of the examples showing how less affluent communities are more vulnerable to wildfire hazard compared to those which are more affluent.

Since 1984, wildfires have caused 1,900 deaths, affected nearly 6 million people and cost more than $52 billion [1]. Due to their geographic locations and natural beauty areas at wildfire risk are often populated by higher-income groups, with media focus on celebrities such as Neil Young and Miley Cyrus losing their homes in the recent Woolsey fire of 2018. This often overshadows the lower-income households who lack the resources to mitigate wildfire risk. This came to light during the 2017 Sonoma County wildfires where many rural households in low-income neighbourhoods and immigrant communities could not afford insurance, rebuilding costs nor continual investment in fire safety [6]. Wildfires are a natural and necessary hazard and an underlying part of a vegetated land life cycle. However, what is an unavoidable component in many landscapes and potentially not that threatening if managed well, can turn into a billion-dollar disaster due to population vulnerability.

What can be Done?
In general, emergency planning and mitigation strategies need to take diverse populations into consideration. This could be done by engaging vulnerable groups and federal aid such as governmental “gardeners” who help less affluent communities remove underbrush and trim trees. There should also be governmental aid regarding evacuation procedures, with additional transport available.

US wildfire risk map from August 2018. Combining this with a vulnerability map would improve wildfire mitigation

Image caption: US wildfire risk map from August 2018. Combining this with a vulnerability map would improve wildfire mitigation. Source: Image from Wikimedia

Cultural experience with wildfires also has an impact on population vulnerability. Native American culture uses fire to manage and even enhance landscapes considering wildfires a natural process [1]. This means they have a better understanding of the risk that wildfires pose. In contrast and perhaps more relevant to the recent wildfires is the language barrier between Hispanic communities and emergency communication in areas with large Hispanic communities. During the 2014 Washington Fires, language barriers meant that Hispanic farm-workers did not receive an evacuation notification from authorities as the local Spanish radio station did not receive any emergency information [1]. During the 2017 wildfires, emergency departments and radio stations in Northern California and Santa Barbara had difficulties when releasing accurate bilingual information in time, meaning that large parts of the community did not get enough warning [7].

Wildfire disasters impact the lives of the most vulnerable populations and as such are a product of both social and ecological circumstances. The frequency of devastating wildfires is likely to increase with climate change creating warmer and drier conditions, wildland-urban interfaces experiencing more development and fire fuels continuing to accumulate [8]. Considering the variability of communities to create mitigative measures, their capacity to recover and cultural differences with wildfire experience will all contribute to reducing the impacts from wildfire disasters. It is therefore imperative that wildfire management and factors influencing social vulnerability are explored together in a “socio-ecological” manner to create more resilient communities and reduce vulnerability to wildfires.

 

References

[1] Doerr SH, Santín C. Global trends in wildfire and its impacts: perceptions versus realities in a changing worldPhilos Trans R Soc B Biol Sci. The Royal Society; 2016;371.

[2] Davies, I. P., Haugo, R. D., Robertson, J. C., & Levin, P. S. (2018). The unequal vulnerability of communities of color to wildfire. PloS one13(11).

[3] Sharkey P. Survival and Death in New Orleans: An Empirical Look at the Human Impact of KatrinaJ Black Stud. 2007;37: 482–501.

[4] Collins TW, Bolin B. Situating Hazard Vulnerability: People’s Negotiations with Wildfire Environments in the U.S. Southwest. Environ Manage. Springer-Verlag; 2009;44: 441–455. 

[5] Yonetani M, Albuja S, Bilak A, Ginnetti J, Howard C, Kok F, et al. Global Estimates 2015: People Displaced by Disasters [Internet]. Geneva; 2015. 

[6] Collins TW. What Influences Hazard Mitigation? Household Decision Making About Wildfire Risks in Arizona’s White Mountains. Prof Geogr. Taylor & Francis Group; 2008;60: 508–526. 

[7] Axelrod J. California wildfires spark issues of bilingual emergency communications. American City & County. Dec 2017. http://americancityandcounty.com/fire/california-wildfires-spark-issues-bilingual-emergency-communications.

[8] Schoennagel T, Balch JK, Brenkert-Smith H, Dennison PE, Harvey BJ, Krawchuk MA, et al. Adapt to more wildfire in western North American forests as climate changes. Proc Natl Acad Sci. 2017;114: 4582–4590.

Back to top


Vulnerability of California to drought in the context of a changing climate

by Duncan Sly

Conditions of prolonged and/or exceptional water scarcity, or drought, have been known to occur all across the world in many different climatic zones. However, there are certain locations where vulnerability to these extreme conditions is particularly pronounced. Perhaps the most well-known case is that of California, where the region has been repeatedly exposed to extreme weather phenomena in recent years and decades, with the state having experienced four major droughts since 1976, two of which have occurred since 2007.

 

MSC Geohazards Blog  California drought

Image Caption: Extent and severity of drought conditions in California between 2014 and 2017. Source: Image by US Department of Agriculture Drought Monitor

Population Growth and Resource Depletion
California is the most populous state in the U.S., with over 40 million inhabitants. This, in turn, has substantially raised the region’s vulnerability profile in the context of extreme weather and climate. Of course, as an area’s population increases, the rate of resource consumption also rises to compensate. For example, the state’s water consumption has doubled between 1960 and 2015, as a result of consequent increases in agricultural activity to sustain the observed population growth [1]. This trend, ultimately, is unsustainable when considering the naturally dry climatic regime of California. The region’s water supply is heavily sourced from snowpack on the Sierra Nevada, providing up to 30% of the state’s reserves each year, following winter storage from snowfall, and subsequent melting in the summer [2]. However, this historically reliable resource has become increasingly strained due to inhibited precipitation patterns in recent years owing to a warming, drying climate [3]. The ever-growing population of California is therefore left with an even lower supply of water to distribute to everyone than would be the case without the observed changes in snowpack, making the region extremely vulnerable to drought conditions.

Social Inequities in Vulnerability to Drought
Whilst droughts in California pose a severe threat to the entire region, these impacts are felt disproportionately amongst the state’s population, with ethnic minorities and low-income groups, particularly in rural areas, being most greatly affected [4]. This is because these social groups have often been found to rely on private wells for their water supply, as adequate public water services have not been established in many of these settlements [5]. For instance, communities with significant proportions of Hispanics in California were found to be recipient of lower water allowances, regardless of financial status, during the severe 2014 drought [6], indicating that such social groups have an amplified vulnerability to drought in California. This situation is compounded by the induced agricultural losses that have occurred as a result, with more than 18,000 job losses [7], exacerbating many of these communities’ water scarcity concerns. Furthermore, the disproportionate hardships endured by these social groups also has an effect on food prices across the country who depend on much of the foods and crops that are generated in California, in response to rising production costs [8].

The Case of the 2011-2017 Drought
There is no better demonstration of California’s vulnerability to drought than the sequence of events that took place between 2011 and 2017. During this prolonged drought, conditions were the driest in the region’s history, making it an unprecedented event [9]. The main causes of this can be linked to cooler-than-average sea surface temperatures in the tropical Pacific Ocean. This promoted persistent high pressure over the west coast of California, which blocked winter storms from reaching the Sierra Nevada mountains [10]. As a result, the state-wide snowpack level was as little as 6% during part of 2014, forcing the Californian government into a mandatory water use ban [11].

Houseboats in California’s drought-lowered Oroville Lake in April 2015. Source: Image by ray_explores

Image Caption: Houseboats in California’s drought-lowered Oroville Lake in April 2015. Source: Image by ray_explores, Flickr.

These reductions in precipitation and water available for irrigation were being balanced by increased groundwater pumping [12]. However, such water reserves are non-renewable, making this approach highly unsustainable in the event of similar crises in future. Hence, as major droughts are expected to become more frequent and severe in response to climate change, the toll taken on California’s fragile water resources will continue to grow, increasing the state’s vulnerability to these extreme weather events with time.

MSC Geohazards Blog  California drought Changes in California’s groundwater storage through time. Source: Image by Chappelle et al. (2017).
Figure caption: California drought Changes in California’s groundwater storage through time. Source: Image by Chappelle et al. (2017).
 

Future Directions: The Issue of Communication
Arguably the main issue that is central to every aspect contributing to California’s vulnerability to drought is how to effectively communicate these problems to the very same people who are considered vulnerable. In other words, how can we make the people we are trying to protect care enough about what it is they need to be protected from to take action? One of the main issues is that the majority of people have not felt the truly catastrophic effects of a prolonged drought before. Whilst past droughts such as the 2011-2017 event have been severe, people have generally managed to continue their daily lives with little interruption. For example, urban water supplies in California have been successfully managed and maintained during past droughts, but only as a result of considerable intervention involving groundwater extraction [1], [12].

However, the perceptions of rural and agricultural populations are also highly conflicted, amplifying these groups’ vulnerability to drought as well. For example, in March 2014, the NOAA issued a 50% chance of an El Nino proliferating throughout the year. This announcement led many people within the agricultural community to speculate that drought conditions would improve, with the 1997-98 El Nino event that resulted in heavy rains and flooding across California fresh in people’s memories. As a result, these people develop an oversimplified perception about the predictability of climate, having unrealistic expectations of forecasting agencies to accurately anticipate the possibility of changes in climate [13]. Subsequently, this misperception serves to heighten these agricultural populations’ vulnerabilities to drought, as they expect (and hence only prepare) for one outcome: that conditions will improve. This, in turn, has ramifications for the remaining Californian population who depend on these rural communities for their agricultural production, compounding these groups vulnerability to drought as well.

These misperceptions therefore need urgently addressing at the governmental level, who need to emphasise the inherent uncertainty prevalent in all weather and climate forecasting. Furthermore, discussions of mitigation and adaptation options also need to take priority at the governmental level, with such discussions communicated clearly to the general population so as to encourage cooperation with any policies put forward, and to reduce overall vulnerability to droughts.

 

References

[1] AghaKouchak, A., Feldman, D., Hoerling, M., Huxman, T., and Lund, J. (2015). Water and climate: Recognize anthropogenic drought. Nature News524(7566), 409.


[2] Belmecheri, S., Babst, F., Wahl, E. R., Stahle, D. W., and Trouet, V. (2016). Multi-century evaluation of Sierra Nevada snowpack. Nature Climate Change6(1), 2.


[3] Seager, R., and Vecchi, G. A. (2010). Greenhouse warming and the 21st century hydroclimate of southwestern North America. Proceedings of the National Academy of Sciences107(50), 21277-21282.

[4] Feinstein, L., Phurisamban, R., Ford, A., Tyler, C., and Crawford, A. (2017). Drought and equity in California. Pacific Institute.


[5] Bliss, L. (2015). A Historic Drought Meets a Century of Disparity in California’s Central Valley. Citylab. Available online at: https://www.citylab.com/environment/2015/10/before-californias-drought-a-century-of-disparity/407743/.

[6]
Wikstrom, K., Miller, T., Campbell, H. E., and Tschudi, M. (2019). Environmental inequities and water policy during a drought: burdened communities, minority residents, and cutback assignments. Review of Policy Research36(1), 4-27.


[7] Thompson, A. (2015). Drought takes $2.7 billion toll on California agriculture. Climate Central. Available online at: https://www.climatecentral.org/news/drought-cost-california-agriculture-19061.

[8] Cooley, H., Donnelly, K., Phurisamban, R., and Subramanian, M. (2015). Impacts of California’s ongoing drought: agriculture. Pacific Institute: Oakland, CA, USA, 24.

[9] Hanak, E., Mount, J., Chappelle, C., Lund, J., Medellín-Azuara, J., Moyle, P., and Seavy, N. (2015). What if California’s drought continues? Public Policy Institute of California, 6894726-181.

[10] Seager, R., Hoerling, M., Schubert, S., Wang, H., Lyon, B., Kumar, A., and Henderson, N. (2015). Causes of the 2011–14 California drought. Journal of Climate28(18), 6997-7024.

[11] Nagourney, A. (2015). California imposes first mandatory water restrictions to deal with drought. New York Times.
[12] Chappelle, C., Hanak, E., and Harter, T. (2017). Groundwater in California: just the facts. Public Policy Institute of California. Available online at: https://www.ppic.org/publication/groundwater-in-california/.

[13] Werner, K. V., McNutt, C., Anderson, M., Ewald, J., Gleason, K. L., Hameedi, M. J., and Wulff, R. (2015). California drought: 2014 service assessment. Available online

 

Further Reading

1.    AghaKouchak, A., Feldman, D., Hoerling, M., Huxman, T., and Lund, J. (2015). Water and climate: recognize anthropogenic drought. Nature News, 524(7566), 409.
2.    Cheng, L., Hoerling, M., AghaKouchak, A., Livneh, B., Quan, X. W., and Eischeid, J. (2016). How has human-induced climate change affected California drought risk?. Journal of Climate, 29(1), 111-120.
3.    Christian-Smith, J., Levy, M. C., and Gleick, P. H. (2015). Maladaptation to drought: a case report from California, USA. Sustainability Science, 10(3), 491-501.
4.    Moser, S. C. (2010). Communicating climate change: history, challenges, process and future directions. Wiley Interdisciplinary Reviews: Climate Change, 1(1), 31-53.
5.    Webster, M. (2003). Communicating climate change uncertainty to policy-makers and the public. Climatic Change, 61(1), 1-8.

Back to top


The vulnerability of New Orleans: A lesson learnt too late

By Anisha Desai

New Orleans, nicknamed ‘the Big Easy’, is known for its vibrant jazz music scene, Mardis Gras festival and… Hurricanes. Since being settled by the French in the early 18th century hurricanes have been an integral part of the city’s history [1]. Most memorable perhaps was Hurricane Katrina. Although it was only classed as a Category 3 hurricane on the Saffir-Simpson Scale, when it made landfall just off the coast of Louisiana the impact of it revealed a complex picture of vulnerability within New Orleans

 

Path that Hurricane Katrina took before making landfall in Louisiana as a Category 3 hurricane. Source: The National Oceanic and Atmospheric Administration (NOAA).

Image caption: Path that Hurricane Katrina took before making landfall in Louisiana as a Category 3 hurricane. Source: The National Oceanic Atmospheric Administration (NOAA).
 

Geography of New Orleans
For years before Hurricane Katrina experts had warned that New Orleans was extremely vulnerable to the impact from hurricanes due to the physical exposure of the city [2]. In his 2001 Scientific American article, Mark Fischetti stated that “New Orleans is a disaster waiting to happen” [3]. The Federal Emergency Management Agency (FEMA) listed a hurricane strike in New Orleans as one of the calamitous threats to the nation, on par with a large Californian earthquake [4].

Built within a natural basin below sea level [5] the city was already vulnerable to flooding by storm surges, created by intense hurricanes as their strong winds pushed seawater onto land. Over the years, its vulnerability has increased as the surrounding swamplands were drained to encourage city expansion and prevent disease [6]. At present much of the northern city is more than six feet below sea level [7]. What’s more, storm surges originate just to the south of the city where the Mississippi River flows into the Gulf of Mexico. Hurricanes tracking northwest from Africa are fuelled by the warm moisture from the Gulf of Mexico and reach maximum intensity enabling these storm surges to form that are responsible for most hurricane-related fatalities. Due to the bowl-shaped structure of New Orleans, when Katrina hit and formed 19 feet high storm surges the city was flooded, and once water entered it could not escape. Instead it lay stagnant for weeks, soaking tens of thousands of homes in a festering soup of waste, chemicals, micro-organisms, and eventually mould [2].

Human interference has also destroyed wetlands and barrier islands that used to act as natural defences against storm surges, further increasing vulnerability of the city [2]. Dams built upriver of the city reduced the amount of sediment in the river by up to 67%, and levees along the Mississippi River reduce the amount of sediment flowing into the wetlands. This means that the river is not naturally replenishing the wetlands, and so over the past 50 years they have been disappearing at a rate of 60 km per year. This effect has been further exacerbated by the construction of canals in and around New Orleans that have increased the influx of saltwater into the freshwater marshes and wetlands, that kills native plants [7].
 

Levees
Levees are walls that prevent waterways from overflowing and flooding nearby areas. Over thousands of years the Mississippi River has periodically overflown, depositing sand and silt onto the active floodplain, forming a ridge or “natural levee” [6]. When the French settled, these ongoing floods convinced the settlers to construct private levee systems to protect their properties. By 1735 this system had grown and expanded to 35 miles. Authorised for construction in 1965 after Hurricane Betsy flooded much of the city, the modern system now stretches 350 miles along the Mississippi River and around Lake Pontchartrain [7].

The Army Corps of Engineers proposed two plans designed to protect the city from a fast-moving Category 3 storm, termed “Standard Project Hurricane”. The first “Barrier Plan” involved barriers and gates, however it was rejected in the 1970s due to environmental impact issues raised by the ‘Save Our Wetland’ organisation. The second “High Level Plan”, implemented in the 1980s, involved raising the height of the levees by building floodwalls on top of them, or constructing walls in place of a levee when space was insufficient for its broad base. Most commonly used was the I-wall as this was the cheaper option even though T- walls offered more resistance. However, failure of these I-walls was the reason for the severe flooding that occurred during Hurricane Katrina, with 53 walls in total being breached under the impact of the storm. Corps concluded in 2006 that the levee system had been vulnerable to failure due to insufficient funding, information and poor construction, and at the time tests of the system had been mis-interpreted [5].

Not only did the levee system fail, but its mere presence caused the populace of New Orleans to have a false sense of security and complacency that contributed to the lack of evacuation plans during Hurricane Katrina. Those living near the breaches were most prone to loss of property, and if not evacuated, loss of life. Inevitably the poor and the infirm communities were the most vulnerable.

I-walls (left) are cheaper but less stable than T-walls (right) as they rely mainly on gravity to keep them down, whereas T-walls are reinforced on either side and so are less likely to be breached
Figure caption: I-walls (left) are cheaper but less stable than T-walls (right) as they rely on gravity to keep them down, whereas T-walls are reinforced on either side and so are less likely to be breached [5].
 

The Future
New Orleans is subject to high exposure to future hurricane events due to its geographical location. Hurricane Katrina demonstrated the high vulnerability of the city due to its poor defences system, lack of evacuation plans, destruction of natural defences, lack of public awareness and general complacency of the populace. The event also highlighted the cost to property, and more importantly, to human life caused by cutting corners in the construction of floodwalls. Sadly, it also showed that even in the richest country in the world social inequalities can have catastrophic effects.
The US Army Corps of Engineers still have not realised their mistake, and rather than spending money on improving the cities defences, they spent $14.6 billion rebuilding the same levee system that failed during Katrina [8]. This again raises complacency within the region, thereby further increasing the vulnerability of New Orleans to future events. There have been plans to increase the size of the wetlands by 100 km2 by 2031, however this is proving to be a slow and difficult plan to enact. Some studies have suggested that the best course of action would be to allow the marshes at the river mouth to vanish altogether in order to allow those nearer the city to flourish again [6].

There is concern that the current rate of climate change will cause hurricanes the size of Katrina to be ever more likely in the future [8]. Not only do warmer temperatures increase the capability of hurricanes to carry moisture that fuels its path of destruction over land, but it also causes hurricanes to move slowly, thereby prolonging the impact in unprepared areas. A future event on par with Hurricane Katrina is likely around the corner, and yet New Orleans remains vulnerable and unprepared for such events, despite its devastating history.

MSc Geohazards Blog Hurricane Katrina

Image caption: Left:Already below sea level, here can be seen water spilling into New Orleans on August 30, 2005. Source: United States Navy.  Right: Hurricane Katrina left over 1,800 dead, destroyed $100 billion worth of property and compromised 800,000 houses, leaving thousands homeless. Source: United States Air Force.
 

References

[1] Fitzpatrick, P. J., 1991, Hurricanes: A Reference Handbook.

[2] Yarnel, B., 2007, Vulnerability and all that Jazz: Addressing Vulnerability in New Orleans after Hurricane Katrina, Technology in Science, 29, 249-255.

[3] Fischetti, M., 2001, Drowning New Orleans, Scientific American.

[4] Townsend, F. F., 2006, The Federal Response to Hurricane Katrina Lessons Learned.

[5] Nelson, S. A., 2012, Why New Orleans is Vulnerable to Hurricanes Geologic and Historical Factors, Tulane University.

[6] Tibbetts, J., 2006, Louisiana’s Wetlands: A Lesson in Natural Appreciation, Environmental Health Perspectives, 114(1), A40-A34.

[7] Below, C., Dierich, C., Erickson, K., & Kjos, R., Environmental Hazards Storm Surge Induced Flooding in New Orleans.

[8] Gibbens, S., 2019, Hurricane Katrina explained, National Geographic.

 

Further Reading

  1. Fischetti, M., 2008, Drowning New Orleans, Scientific American.
  2. Rogers, J. D., Kemp, G. P., Bosworth, H. J., & Seed, R. B., 2015, Interaction between the US Army Corps of Engineers and the Orleans Levee Board preceding the drainage canal wall failures and catastrophic flooding in New Orleans in 2005, Water Policy, 17, 707-723.
  3. Schwartz, J., & Schleifstein, M., 2018, Fortified but still in peril, New Orleans braces for its future, New York Times.
  4. Laska, S. B., & Morrow, B. H., 2006, Social Vulnerabilities and Hurricane Katrina: An Unnatural Disaster in New Orleans, Marine Technology Society Journal, 40(4), 16-26.
  5. Zoraster, R. M., 2010, Vulnerable Populations: Hurricane Katrina as a Case Study, Prehospital and Disaster Medicine, 25(1), 74-78.

Back to top

Resources:

Newsletters:
Spring 2019 Autumn 2018 | March 2018

General inquires: 
Dr Christopher Kilburn - How To apply

Connect with us:
Twitter Youtube | LinkedIn