Waterlogged Data: Widespread Flooding Expected by 2030
Print Issue: July 2020
The mighty Mississippi River winds its way for 2,320 miles across the United States, serving myriad purposes as it flows steadily toward the Gulf of Mexico—an essential waterway for billions of dollars’ worth of trade, a diverse ecosystem for wildlife, and a cultural touchstone for many people who grew up reading the stories of Mark Twain. But the river is also susceptible to massive flooding, as witnessed in 2019.
The long duration of the flooding in the Mississippi River last year rivaled 1927’s Great Flood—the worst in modern history on the lower Mississippi River—and some areas remained above flood stage for months. According to the January 2020 National Climate Report from the U.S. National Oceanic and Atmospheric Administration (NOAA), 2019’s flooding along the Mississippi River and its tributaries across 13 states caused an estimated $6.23 billion in damage, making it the 51st costliest weather disaster since NOAA began tracking them in 1980.
In March, NOAA forecasters predicted widespread—but not as prolonged—flooding again in 2020.
Flooding is hardly contained to river basins, however. Rising sea levels are expected to exponentially increase the frequency of coastal flooding, according to an April 2020 report from researchers at the University of Illinois at Chicago, the U.S. Geological Survey, and the University of Hawai’i at Manoa.
“For many coastal regions, projections of global sea-level rise by the year 2100 (e.g., 0.5–2 meters) are comparable in magnitude to today’s extreme but short-lived increases in water level due to storms. Thus, the 21st century will see significant changes in coastal flooding regimes (where present-day, extreme-but-rare events become common), which poses a major risk to the safety and sustainability of coastal communities worldwide,” the authors wrote in Scientific Reports, a Nature Research journal. The authors found that present-day 50-year extreme water levels will be exceeded annually before 2050 for 70 percent of U.S. coastal regions, and by 2100, current extreme water levels will be exceeded at almost every high tide for 90 percent of the U.S. coastline.
“Present-day extreme water-level events will become commonplace within the next few decades,” the authors concluded. Current emissions trajectories and sea-level projections double the odds of extreme coastal flooding every five years in most U.S. locations, they found, and the near constancy of this rise bears potentially startling consequences: “Sea-level rise will likely increase the odds of flooding by a thousand-fold... in a half-century,” they wrote.
Global rivers and coastlines are at high risk of devastating flooding as well. According to a recent analysis from nonprofit World Resources Institute’s Aqueduct Floods tool, the number of people affected by floods will double worldwide by 2030.
According to the tool, which analyzes flood risks and solutions globally, the number of people affected by riverine floods will rise from 65 million in 2010 to 132 million in 2030, and the number of people affected by coastal flooding will increase from 7 million to 15 million.
Economies will also be impacted, the research found. Since 1980, flooding has caused more than $1 trillion in global losses, but as flooding risks increase, urban property damage from riverine floods will increase from $157 billion to $535 billion annually, and urban property damage from coastal storm surges and sea level rise will increase tenfold—from $17 billion to $177 billion each year, Aqueduct Floods reported.
Researchers for Aqueduct Floods calculated the increased flood risk by balancing hazard exposure (flooding) with vulnerability (who is at risk, who will be affected, and what mitigation tools are available). They found that while riverine flooding fluctuates, any coastline currently experiencing flooding will only experience more in the future, says Samantha Kuzma, geospatial associate with World Resources Institute (WRI).
Climate change will intensify flooding frequency and levels, the research found. Heavier rains inland will drive approximately half of riverine flooding increases, and more frequent and intense coastal flooding could render existing flood protection measures like dikes and levees obsolete.
Socioeconomic changes also put more people at risk, the research found. New development near rivers stresses existing flood prevention infrastructure and places more people and organizations in harm’s way.
Along coastlines, 15,500 more people and $1.1 billion more in urban assets are predicted to be affected by flooding in the next decade; urbanization accounts for 87 percent of increased flood risks by 2030.
In addition to direct effects from flooding on populations and properties, secondary effects begin to compound, including large-scale population displacement.
“Our analysis looks specifically at the direct impacts of flooding—actual damage to infrastructure,” Kuzma tells Security Management. “We’re not even considering the secondary impacts—what if a flood displaces people from their homes? What are the costs associated with that? Or what if you can’t go to work because the streets are flooded and your business is closed down? The secondary effects of natural disasters start to compound. We can already see it with the coronavirus pandemic; even though it’s not a nature-based disaster—disruption is a huge cost for economies and the stability of our lives.”
The COVID-19 pandemic also complicates flood prevention initiatives; not only are funds being reallocated to address the crisis, but traditional flood or natural disaster response is endangered by reduced emergency management capabilities, restrictions on safely housing refugees from disasters, and curtailed community engagement efforts, Kuzma says.
“Right now, we’re even more vulnerable if a flood were to hit; all of our resources are tied up trying to battle this pandemic, and we would be exposed and vulnerable in a whole new way,” she adds. “And as we expect climate change to intensify storms and make rainfall heavier in certain parts of the world, we really need to prepare for [simultaneous crises] like this so we can control those secondary effects and reduce the overall impact of these sorts of disasters.”
However, the stimulus packages and funding measures being pushed through governments in response to the pandemic provide an opportunity to boost economies and flood protection, the report noted. Flood defenses require long-term maintenance and create local jobs. These measures also mitigate risks of further economic damage from severe flooding.
Flood protection measures offer a strong return on investment for waterfront communities. For the three countries with the highest number of people affected by riverine flooding—India, Bangladesh, and Indonesia—small investments have big payoffs. In India, every $1 spent on flood prevention infrastructure like dikes may result in $248 in avoided damages, Aqueduct Floods found. The research also recommended considering green infrastructure like mangroves, reefs, and sand dunes to act as natural buffers to coastal storms and erosion.