Understanding how water moves and changes worldwide is more important than ever due to climate change, but monitoring inland water in the tropics is not easy. Most satellites are optical and take photos of surfaces. They cannot see through the thick cloud cover and dense vegetation that conceal the rivers, lakes, and wetlands below.
Now, a team led by Berkeley CEE researchers has developed a new way to map water on land in the tropics. Called the UC Berkeley Random Walk Algorithm WaterMask (Berkeley-RWAWC), this advanced monitoring technology uses L-band microwaves from the Cyclone Global Navigation Satellite System (CYGNSS) to "see" water hidden beneath visual barriers, like tree canopies and clouds. It also incorporates a computer vision algorithm that works with CYGNSS data to differentiate between land and water.
In a study recently published in Water Resources Research, the researchers used Berkeley-RWAWC (pronounced like "rock") to generate a detailed monthly map of water bodies from 37.4°N to 37.4°S, showing where water is and how it changes over time. Their findings provide a clearer picture of seasonal water dynamics in these regions.
"Using Berkeley-RWAWC, we can better understand seasonal and yearly changes in tropical water," said CEE Ph.D. student Tianjiao Pu, the study's first author. "The monthly map provides fresh insights into these vital ecosystems, helping to close the gap in tropical water monitoring."
Researchers aim to help these communities by using Berkeley-RWAWC to track floods and improve hydrologic models. "The Sudd wetlands in South Sudan, for example, have been experiencing catastrophic floods for multiple years in a row, displacing over a million people and adding to an already dire situation in the region," said CEE Assistant Professor Cynthia Gerlein-Safdi, the study's principal investigator. "Improved maps of flooding in the area can provide new tools for humanitarian aid to be released before the next flood event."
Other study authors include Ying Xiong, Mengze Li, and Eric Kort from the University of Michigan, and A. Anthony Bloom from the Jet Propulsion Laboratory at Caltech.
Learn more about their research in the full article in Berkeley Engineering here.