Changing sea levels can affect the population living in coastal areas. A rising sea level inundates low lying areas, causes coastal erosion and flooding. A high sea level also makes coastal infrastructure more susceptible to damages from storms. Some of the low lying coastal areas are predicted to submerge by the end of the 21st century.
A relative sea-level change is the measure of the rise or fall of the ocean relative to the land at a particular location. Two major factors contribute to the rise in sea level
- Change in the volume of glacier and ice sheets due to the increase in global temperature
- Warm water expands causing the overall volume to increase
- Land subsidence caused by the sudden sinking of land due to the natural process of tectonics, glacial isostatic adjustment, sediment loading, and soil compaction and human activities such as groundwater extraction and oil and gas production
For the first time, a research team from Arizona State University has tracked entire California’s coast’s vertical land motion using interferometric synthetic aperture radar (InSAR). The InSAR is a state-of-the-art satellite-based radar that provides precise measurements of the land surface rise and falls with millimeter accuracy. It produces highly accurate deformation maps of the Earth’s surface at 10s m resolution over a 100s km spatial extent.
This NASA funded research project, published in Science Advances, comprised of lead author and graduate student Em Blackwell, principal investigator Manoochehr Shirzaei, Chandrakanta Ojha, and Susanna Werth, from the ASU School Earth and Space Exploration.
The team has identified local hotspots on the sinking coast in San Diego, Los Angeles, Santa Cruz, and San Francisco. An estimated population of 4 to 8 million in these areas are at higher risk of future flooding due to sea-level rise caused by rapid land subsidence.
The study measured California’s entire coastline from 2007 to 2018. Compiling over 1000s of satellite images, the team made a vertical land motion map with 35-million-pixel at ~80 m resolution, comprising a wide range of coastal uplift and subsidence rates. The general public can freely download the data. San Francisco, Monterey Bay, Los Angeles, and San Diego are the four major metropolitan areas majorly affected.
An estimated 40 million people globally were at risk of 1 in a 100-year coastal flooding hazard as of 2005. This number is expected to triple by 2070. These estimates often rely on rising sea-level projection and do not factor the vertical land movement.
Globally, the coastal population is expected to grow to over 1 billion people by 2050. Coastal flood risk in these communities will depend on relative sea-level rise and vertical land motion. Hence, it is crucial to include land subsidence into regional projections to identify potential flooding areas in the urbanized coast.
The research team is hopeful that the scientific community can build on their results to measure and identify coastal flooding hazards.
Do you want to publish on Apple News, Google News, and more? Join our writing community, improve your writing skills, and be read by hundreds of thousands around the world!