How will accelerating climate change impact land surface hazards?
While climate science is focused on the acceleration of global threats under changing regimes: heat waves, fires, floods, and rising sea levels, the climate impact on solid earth hazards, such as landslides, debris flows, river aggregation and flooding, has received much less attention.
Yet, the Earth’s surface – the solid part, is incredibly sensitive to torrential rainstorms, dramatically changed by wildfire and other processes that instantly change vegetation and land cover.
These perturbations are amplified when “extreme” events occur greatly out of proportion to annual or decadal scale processes as predicted and currently observed.
Not only does climate change affect the Earth’s surface, but we also know that other triggers like earthquakes and volcanoes can rapidly trigger land surface change and initiate a cascade of subsequent processes that are amplified by accelerating climate change.
The August 2023 Hurricane Hilary was a Category 4 Pacific hurricane/Tropical Storm that triggered an unprecedented tropical storm warning for Southern California, extending from the Mexico-US border to regions north and east of Los Angeles.
Unlike most wintertime atmospheric rivers, which are narrow, concentrated bands of precipitation, Hurricane Hilary distributed heavy rainfall, providing an opportunity to study the widespread geomorphic and societal impact of a rare precipitation event.
The most severely affected regions have been arid and mountainous desert regions, which suffered heavy rainfall in excess of typical annual totals with triggered debris flows, flash flooding and sediment debris waves.This event gave the CLaSH team an opportunity to explore novel science and develop Center protocols around event response activities including improved land surface hazards models, understanding of the impact of precipitation-triggered debris flows on infrastructure, and training of students in field data planning and acquisition following disasters.
Graduate students from multiple institutions and at varying career stages led the field campaign including data collection, providing in-practice opportunities for mentoring and cohort building. The subsequent analyses and publications support a community building initiative and engaging researchers across disciplines in hazard-related science by including new researchers not previously involved in CLaSH.
Geospatial data and observations collected by the CLaSH team capture perishable information in the aftermath of this storm. These data are being made freely and openly available for use by anyinterested parties, including academic and government researchers as well as others.Potential uses could include (but are not limited to) change detection, as well as evaluation of material properties in aid of mechanistic understanding and model parameterization, including quantification of grain size of sedimentary deposits. The data collected during this project also provide a baseline that can be used to evaluate future changes associated with land surface hazards at thestudied locations.
This work was supported by an NSF-RAPID award to the University of Michigan (NSF-#2344994) through the NSF Geomorphology and Land Use Dynamics and Centers for Innovation and Community Engagement in Solid Earth Geohazards programs. To learn more about this project including access to data generated from this research click here.
