Cutting edge satellite monitors water levels in Ohio River Basin

Cutting edge satellite monitors water levels in Ohio River Basin
by Clarence Oxford
Los Angeles CA (SPX) Dec 18, 2024

The Ohio River Basin, spanning from Pennsylvania to Illinois, covers an area nearly as large as France and is home to over 25 million people. A collaborative effort between NASA and the French space agency CNES (Centre National d'Etudes Spatiales) through the Surface Water and Ocean Topography (SWOT) mission now provides researchers with a valuable tool to monitor water levels in lakes, reservoirs, and rivers within this critical watershed.

Since its launch in early 2023, the SWOT satellite has been revolutionizing the measurement of Earth's surface water, recording both the vertical height and horizontal extent of oceans, lakes, rivers, and reservoirs. The mission captures data across nearly the entire globe at least every 21 days. Earlier this year, the team made validated data publicly available, enabling hydrologists and water managers to better monitor freshwater systems worldwide.

"Having these two perspectives - water extent and levels - at the same time, along with detailed, frequent coverage over large areas, is unprecedented," said Jida Wang, a hydrologist at the University of Illinois Urbana-Champaign and a SWOT science team member. "This is a groundbreaking, exciting aspect of SWOT."

The satellite's data allows researchers to track changes in water storage in lakes and reservoirs over time, improving calculations of river discharge, or the volume of water flowing through a particular section of a river. For instance, SWOT data collected between July 2023 and November 2024 reveals water levels across the Ohio River Basin, which eventually drains into the Mississippi River. A visualization of the data highlights water levels above sea level, ranging from less than 330 feet (100 meters) in dark purple to over 1,600 feet (500 meters) in yellow. Such insights are vital for monitoring water availability in local and regional watersheds.

Enhancing Water Resource Management

Historically, estimating freshwater availability in river basins has been challenging due to limited data coverage. Ground-based gauges, airborne surveys, and traditional satellites provide partial measurements of either water level or extent, often at different times. For basins with significant human interventions, like dams and reservoirs, computer models can struggle to simulate water behavior accurately.

"Traditional water models often don't work very well in highly regulated basins like the Ohio because they have trouble representing the unpredictable behavior of dam operations," explained George Allen, a freshwater researcher at Virginia Tech and SWOT science team member.

The Ohio River Basin, like many U.S. river systems, is managed by numerous entities operating dams and reservoirs. While local managers may understand their specific reservoirs, achieving a holistic view of water availability across the entire river basin has been difficult. SWOT's ability to simultaneously monitor both lakes and rivers offers a more unified perspective.

"The data lets water managers really know what other people in these freshwater systems are doing," said Colin Gleason, a hydrologist at the University of Massachusetts Amherst and SWOT science team member.

Future Potential and Challenges

While the SWOT satellite's data provides unprecedented insights, the mission still faces challenges. The sheer volume of high-resolution water data requires significant processing and analysis. Researchers remain optimistic that SWOT's contributions will transform water management practices worldwide by filling longstanding gaps in freshwater monitoring.