Floods are becoming more deadly in the desert

Desert regions may seem synonymous with drought – where dry, parched landscapes dominate the narrative of environmental challenges. However, new research reveals that these arid areas face a far more unpredictable and devastating threat from flooding.

While drought has long been considered the primary concern in deserts, the increasing frequency and intensity of extreme rainfall events are proving to be equally, if not more, destructive.

Desertification and catastrophic flooding

A new study from the USC Viterbi School of Engineering and the Institute de Physique du Globe de Paris at the University of Paris Cité has uncovered a worrying trend. The experts found that desertification is escalating the severity of flood impacts on port cities in the Middle East and North Africa.

The research was focused on the deadly 2023 floods in Derna, Libya, which claimed more than 11,300 lives. The experts noted that soil erosion, intensified by desertification, played a significant role in the catastrophe.

Drought and intense rainfall can turn deadly

Study co-author Essam Heggy is a research scientist at the USC Microwave Systems, Sensors, and Imaging Lab (MiXIL). He pointed out that these increasingly arid conditions, interrupted by intense rainstorms, are generating lethal mudflows that the region’s aging dams struggle to control.

“Together, these two extreme conditions – drought and intense rainfall – are enhancing soil erosion, creating deadly floods,” said Heggy. “The evidence is clear in our paper, ‘Assessing flash flood erosion following Storm Daniel in Libya.'”

In autumn 2023, Storm Daniel (also known as “Medicane Daniel”) struck Libya’s eastern coast, resulting in unprecedented flash floods. Researchers estimate this was Africa’s deadliest flood in over a century. Yale Climate Connections noted that such floods have not been observed in over 100 years.

Dangerous combination of desert conditions

The researchers noted that a mix of factors contributed to this devastating flood: unusually high rainfall, the collapse of two dams, and the failure of the region’s water infrastructure.

Jonathan Normand is a visiting graduate student at the USC AWARE Center and first author of the study.

“Sediment loading from soil erosion increased the water’s density, amplifying the flood’s destructive power. This led to widespread infrastructure failure in Derna, where 66% of the city’s urban area sustained moderate-to-high damage,” explained Normand.

Case study: the fallout of storm Daniel

Using advanced radar technology, the research team analyzed the changes in surface texture before and after the storm. This data allowed them to map erosion and assess the extent of the damage.

“The flow was heavily loaded with eroded soil, which increased the destructive nature of the floods and contributed to the collapse of the dams,” said Heggy.

“Current runoff models fail to account for the full impact of surface erosion in deserts. But radar satellites overcome this limitation. Improving the monitoring of arid watersheds using these technologies will be critical to mitigating flood risks across the Sahara, the Arabian Peninsula, and other desert regions.”

Preventing desert disasters

Normand emphasized the need for better technological resources to study desert dynamics.

“You can post on social media from the middle of a desert thanks to hundreds of communication satellites, but we still don’t have enough satellites to fully understand Earth’s surface processes in deserts,” said Normand.

The research team warned that the situation seen in Libya could easily happen again in other populous areas of North Africa and the Arabian Peninsula.

“The deadliest enemy is our own belief that these extreme events are rare and won’t repeat,” said Heggy. “Climate models tell us they will come back stronger. Policymakers in the region need to listen to the science before it’s too late.”

Global implications of desert flooding

While the Middle East and North Africa face the immediate threat of desert floods, the implications of these extreme weather events extend far beyond the region.

Climate scientists warn that similar patterns of desertification, soil erosion, and unpredictable rainstorms are becoming more prevalent in other arid regions across the globe, from the southwestern United States to parts of Central Asia.

As these regions become more vulnerable, the risks to human life, infrastructure, and agriculture grow exponentially. In particular, the combination of desertification and flooding could have a profound impact on global food security.

Arid regions often rely on limited but crucial agricultural zones that are susceptible to erosion and flood damage.

As storms intensify and soil stability decreases, these agricultural areas could become less productive, exacerbating existing challenges related to water scarcity and food supply.

Re-evaluating the flood potential of deserts

Understanding the mechanisms behind desert floods is not just a local concern but a global priority.

Desert environments worldwide must be re-evaluated for their flood risk potential, and proactive measures should be taken to safeguard vulnerable communities and ecosystems.

The tragic floods in Libya serve as a stark reminder that these extreme weather events are no longer isolated incidents, but part of a growing pattern of climate-related disasters that could affect arid regions globally.

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