The risk of ‘cascading’ natural disasters is rising

A man watches wildfires in California, 2013. Image: Getty.

In a warming world, the dangers from natural disasters are changing. In a recent commentary, we identified a number of costly and deadly catastrophes that point to an increase in the risk of “cascading” events – ones that intensify the impacts of natural hazards and turn them into disasters.

Multiple hazardous events are considered cascading when they act as a series of toppling dominoes, such as flooding and landslides that occur after rain over wildfires. Cascading events may begin in small areas but can intensify and spread to influence larger areas.

This rising risk means decision-makers, urban planners and risk analysts, civil engineers like us and other stakeholders need to invest more time and effort in tracking connections between natural hazards, including hurricanes, wildfires, extreme rainfall, snowmelt, debris flow, and drought, under a changing climate.

Cascading disasters

Since 1980 to January 2018, natural disasters caused an inflation-adjusted $1,537.4bn in damages in the United States.

The loss of life in that period – nearly 10,000 deaths – has been mounting as well. The United States has seen more billion-dollar natural disaster events recently than ever before, with climate models projecting an increase in intensity and frequency of these events in the future. In 2017 alone, natural disasters resulted in $306bn losses, setting the costliest disaster year on record.

We decided it was important to better understand cascading and compound disasters because the impacts of climate change can often lead to coupled events instead of isolated ones. The United Nations Office for Disaster Risk Reduction, or UNISDR, claims: “Any disaster entails a potentially compounding process, whereby one event precipitates another.”

For example, deforestation and flooding often occur together. When vegetation is removed, top soil washes away and the earth is incapable of absorbing rainfall. The 2004 Haiti flood that killed more than 800 people and left many missing is an example of this type of cascading event. The citizens of the poverty-stricken country destroyed more than 98 per cent of its forests to provide charcoal for cooking. When Tropical Storm Jeanne hit, there was no way for the soil to absorb the rainfall. To further complicate existing issues, trees excrete water vapor into the air, and so a sparser tree cover often yields less rain. As a result, the water table may drop, making farming, which is the backbone of Haiti’s economy, more challenging.


Rising risk from climate change

Coupled weather events are becoming more common and severe as the earth warms. Droughts and heatwaves are a coupled result of global warming. As droughts lead to dry soils, the surface warms since the sun’s heat cannot be released as evaporation. In the United States, week-long heatwaves that occur simultaneously with periods of drought are twice as likely to happen now as in the 1970s.

Also, the severity of these cascading weather events worsens in a warming world. Drought-stricken areas become more vulnerable to wildfires. And snow and ice are melting earlier, which is altering the timing of runoff. This has a direct relationship with the fact that the fire season across the globe has extended by 20 per cent since the 1980s. Earlier snowmelt increases the chance of low flows in the dry season and can make forests and vegetation more vulnerable to fires.

These links spread further as wildfires occur at elevations never imagined before. As fires destroy the forest canopy on high mountain ranges, the way snow accumulates is altered. Snow melts faster since soot deposited on the snow absorbs heat. Similarly, as drought dust is released, snow melts at a higher rate as has been seen in the Upper Colorado River Basin.

Fluctuations in temperature and other climatic patterns can harm or challenge the already crumbling infrastructure in the United States: the average age of the nation’s dams and levees is over 50 years. The deisgn of these aging systems did not account for the effects of cascading events and changes in the patterns of extreme events due to climate change. What might normally be a minor event can become a major cause for concern such as when an unexpected amount of melt water triggers debris flows over burned land.

There are several other examples of cascading disasters. In July, a deadly wildfire raged through Athens killing 99 people. During the same month on the other side of the world in Mendocino, California, more than 1,800 square kilometers were scorched. For scale, this area is larger than the entire city of Los Angeles.

When landscapes are charred during wildfires, they become more vulnerable to landslides and flooding. In January of this year, a debris flow event in Montecito, California killed 21 people and injured more than 160. Just one month before the landslide, the soil on the town’s steep slopes were destabilised in a wildfire. After a storm brought torrential downpours, a 5-meter high wave of mud, tree branches and boulders swept down the slopes and into people’s homes.

Hurricanes also can trigger cascading hazards over large areas. For example, significant damages to trees and loss of vegetation due to a hurricane increase the chance of landslides and flooding, as reported in Japan in 2004.

Future steps

Most research and practical risk studies focus on estimating the likelihood of different individual extreme events such as hurricanes, floods and droughts. It is often difficult to describe the risk of interconnected events especially when the events are not physically dependent. For example, two physically independent events, such as wildfire and next season’s rainfall, are related only by how fire later raises the chances of landslide and flooding.

As civil engineers, we see a need to be able to better understand the overall severity of these cascading disasters and their impacts on communities and the built environment. The need is more pronounced considering the fact that much of the nation’s critical infrastructure is aged and currently operate under rather marginal conditions.

A first step in solving the problem is gaining a better understanding of how severe these cascading events can be and the relationship each occurrence has with one another. We also need reliable methods for risk assessment. And a universal framework for addressing cascading disasters still needs to be developed.

A global system that can predict the interactions between natural and built environments could save millions of lives and billions of dollars. Most importantly, community outreach and public education must be prioritised, to raise awareness of the potential risks cascading hazards can cause.

The Conversation

Farshid Vahedifard, CEE Advisory Board Endowed Professor and Associate Professor of Civil and Environmental Engineering, Mississippi State University and Amir AghaKouchak, Associate Professor of Civil & Environmental Engineering, University of California, Irvine.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

 
 
 
 

What Citymapper’s business plan tells us about the future of Smart Cities

Some buses. Image: David Howard/Wikimedia Commons.

In late September, transport planning app Citymapper announced that it had accumulated £22m in losses, nearly doubling its total loss since the start of 2019. 

Like Uber and Lyft, Citymapper survives on investment funding rounds, hoping to stay around long enough to secure a monopoly. Since the start of 2019, the firm’s main tool for establishing that monopoly has been the “Citymapper Pass”, an attempt to undercut Transport for London’s Oyster Card. 

The Pass was teased early in the year and then rolled out in the spring, promising unlimited travel in zones 1-2 for £31 a week – cheaper than the TfL rate of £35.10. In effect, that means Citymapper itself is paying the difference for users to ride in zones 1-2. The firm is basically subsidising its customers’ travel on TfL in the hopes of getting people hooked on its app. 

So what's the company’s gameplan? After a painful, two-year long attempt at a joint minibus and taxi service – known variously as Smartbus, SmartRide, and Ride – Citymapper killed off its plans at a bus fleet in July. Instead of brick and mortar, it’s taken a gamble on their mobile mapping service with Pass. It operates as a subscription-based prepaid mobile wallet, which is used in the app (or as a contactless card) and operates as a financial service through MasterCard. Crucially, the service offers fully integrated, unlimited travel, which gives the company vital information about how people are actually moving and travelling in the city.

“What Citymapper is doing is offering a door-to-door view of commuter journeys,” says King’s College London lecturer Jonathan Reades, who researches smart cities and the Oyster card. 

TfL can only glean so much data from your taps in and out, a fact which has been frustrating for smart city researchers studying transit data, as well as companies trying to make use of that data. “Neither Uber nor TfL know what you do once you leave their system. But Citymapper does, because it’s not tied to any one system and – because of geolocation and your search – it knows your real origin and destination.” 

In other words, linking ticketing directly with a mapping service means the company can get data not only about where riders hop on and off the tube, but also how they're planning their route, whether they follow that plan, and what their final destination is. The app is paying to discount users’ fares in order to gain more data.

Door-to-door destinations gives a lot more detailed information about a rider’s profile as well: “Citymapper can see that you’re also looking at high-profile restaurant as destinations, live in an address on a swanky street in Hammersmith, and regularly travel to the City.” Citymapper can gain insights into what kind of people are travelling, where they hang out, and how they cluster in transit systems. 

And on top of finding out data about how users move in a city, Citymapper is also gaining financial data about users through ticketing, which reflects a wider trend of tech companies entering into the financial services market – like Apple’s recent foray into the credit card business with Apple Card. Citymapper is willing to take a massive hit because the data related to how people actually travel, and how they spend their money, can do a lot more for them than help the company run a minibus service: by financialising its mapping service, it’s getting actual ticketing data that Google Maps doesn’t have, while simultaneously helping to build a routing platform that users never really have to leave


The integrated transit app, complete with ticket data, lets Citymapper get a sense of flows and transit corridors. As the Guardian points out, this gives Citymapper a lot of leverage to negotiate with smaller transit providers – scooter services, for example – who want to partner with it down the line. 

“You can start to look at ‘up-sell’ and ‘cross-sell’ opportunities,” explain Reades. “If they see that a particular journey or modal mix is attractive then they are in a position to act on that with their various mobility offerings or to sell that knowledge to others. 

“They might sell locational insights to retailers or network operators,” he goes on. “If you put a scooter bay here then we think that will be well-used since our data indicates X; or if you put a store here then you’ll be capturing more of that desirable scooter demographic.” With the rise of electric rideables, Citymapper can position itself as a platform operator that holds the key to user data – acting a lot like TfL, but for startup scooter companies and car-sharing companies.

The app’s origins tell us a lot about the direction of its monetisation strategy. Originally conceived as “Busmapper”, the app used publicly available transit data as the base for its own datasets, privileging transit data over Google Maps’ focus on walking and driving.  From there it was able to hone in on user data and extract that information to build a more efficient picture of the transit system. By collecting more data, it has better grounds for selling that for urban planning purposes, whether to government or elsewhere.

This kind of data-centred planning is what makes smart cities possible. It’s only become appealing to civic governments, Reades explains, since civic government has become more constrained by funding. “The reason its gaining traction with policy-makers is because the constraints of austerity mean that they’re trying to do more with less. They use data to measure more efficient services.”  

The question now is whether Citymapper’s plan to lure riders away from the Oyster card will be successful in the long term. Consolidated routing and ticketing data is likely only the first step. It may be too early to tell how it will affect public agencies like TfL – but right now Citymapper is establishing itself as a ticketing service - gaining valuable urban data, financialising its app, and running up those losses in the process.

When approached for comment, Citymapper claimed that Pass is not losing money but that it is a “growth startup which is developing its revenue streams”. The company stated that they have never sold data, but “regularly engage with transport authorities around the world to help improve open data and their systems”

Josh Gabert-Doyon tweets as @JoshGD.