Zoomed-in area showing the average presence of water over five years in the Amazon (very dark colors = close to 100% of the time wet). (Image by Tianjiao Pu)On the map
In the face of climate change, understanding global water dynamics is critical, but monitoring inland water in the tropics is not easy. Most satellites are optical and simply 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 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 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.
According to Ph.D. student Tianjiao Pu, this data is particularly critical for communities in the tropics, which are heavily impacted by climate change and need help preparing for and responding to floods and droughts. For example, Berkeley-RWAWC can be used to track floods to improve hydrologic models.
“The Sudd wetlands in South Sudan have been experiencing catastrophic floods for multiple years in a row, displacing over a million people and adding to an already dire situation on the region,” said Cynthia Gerlein-Safdi, assistant professor of civil and environmental engineering. “Improved maps of flooding in the area can provide new tools for humanitarian aid to be released ahead of the next flood event.”
Berkeley-RWAWC also can be used to model greenhouse gas emissions in tropical wetlands, which are natural emitters of methane. “Berkeley-RWAWC improves the mapping of where and how big these wetlands are, allowing other scientists to then predict the trajectory of these wetlands and their methane emission as the climate warms,” she said.
Learn more: New computer vision-based system monitors seasonal dynamics of tropical water; Berkeley-RWAWC: A New CYGNSS-Based Watermask Unveils Unique Observations of Seasonal Dynamics in the Tropics (Water Resources Research)