Compound Hazards Pose Increased Risk to Highly Populated Regions in the Himalaya

Urbanization trends in the Himalaya are exposing more people to risk from compound hazards such as flooding, landslides and wildfires, a new study published in the journal Science of the Total Environment has found.

The study by a global team of researchers led by Jack Rusk ’22 MEM/ MArch and published in the journal Science of the Total Environment found that only a small proportion of the Himalaya region is susceptible to these compounding threats from multiple hazards, yet almost half of the region’s population is concentrated in those high-risk areas.
 
These compound hazards, which are events where more than one hazard interact and cause multiplicatively destructive consequences, are increasing in likelihood from climate change, according to the latest assessment report by the Intergovernmental Panel on Climate Change.

The study, which was funded by NASA, shows that current patterns of urbanization in the Hindu Kush Himalaya are putting people in harm’s way.

“Our sobering realization is that urbanization processes are concentrating human settlement in these relatively smaller but highly hazardous areas,” says Karen C. Seto, Frederick C. Hixon Professor of Geography and Urbanization Science at YSE and co-author of the study.

Compounding hazards in the Himalaya take many forms. For example, climate change is causing more frequent and intense wildfires, which contribute to landslides by destabilizing slopes. Those landslides can dam waterways swelling from increased precipitation and glacial melt, leading to catastrophic flooding when the dam breaks.

Using data from satellite imagery along with on-the-ground observations of floods, wildfires and landslides, the research team found that that multi-hazard risk was often concentrated in relatively hotter mid-elevation valleys in the Hindu Kush region of the Himalaya with wet soils. Based on 2019 population estimates, this study shows over 36 million people (49% of the region’s population) living in areas highly susceptible to multi-hazards.

“It’s often stated that the Himalaya is a high-risk environment,” says Rusk. “But contrary to studies that describe the entire region as highly hazardous, our study shows that the highest risk areas are relatively small.”

People are attracted to those regions for economic, educational, and political opportunities.

“These areas are conducive to a lot of what makes sustainable livelihoods possible,’’ Rusk says. “But they are also the places where a lot of hazards occur.”

Directing mitigation efforts in urbanizing areas toward multi-hazard risk and hazard interactions, rather than single-hazard risk, can help residents prepare and respond, the study concluded.