The Surface Water and Ocean Topography (SWOT) satellite, a collaboration between NASA and the French space agency CNES, is making significant advances in flood prediction. This innovative satellite provides unprecedented data on water heights across nearly all Earth’s water surfaces, including rivers, lakes, and reservoirs. These bodies of water, critical to Earth’s hydrological cycle, are experiencing increased flooding due to accelerated climate change, which affects precipitation patterns and increases the number of people living in flood-prone areas.
Traditionally, scientists and water managers have relied on stream gauges to measure water levels in rivers for flood prediction. However, these gauges are often spaced widely apart and can be rendered inoperative during flooding events, especially in regions without the resources to maintain them. SWOT offers a revolutionary solution by delivering comprehensive, three-dimensional data on floods, capturing their height, width, and slope. This data enhances the ability to monitor how floodwaters move across landscapes, thus improving the accuracy of flood prediction models.
J. Toby Minear from the Cooperative Institute for Research in Environmental Sciences (CIRES) in Boulder, Colorado, is at the forefront of integrating SWOT data into the National Oceanic and Atmospheric Administration’s National Water Model. This model plays a crucial role in forecasting flooding and its timing along U.S. rivers. By filling the spatial gaps left by insufficient gauge coverage, SWOT data aids in pinpointing the water levels at which flooding begins at specific river locations, enhancing the model’s predictive capabilities.
The SWOT satellite also impacts flood prediction by providing data that allows for better estimation of river slopes and their changes with varying streamflows. The slope of a river significantly affects the speed at which water flows, which is vital for predicting how quickly water will move through a river system and potentially flood areas. Additionally, SWOT measures water levels in tens of thousands of U.S. reservoirs and nearly all natural U.S. lakes larger than two football fields combined, areas previously under-monitored. This comprehensive measurement capability is crucial for understanding how reservoir levels correlate with surrounding land elevations and their potential flooding impacts.
SWOT’s global reach is particularly important in parts of Africa, South Asia, South America, and the Arctic, where existing data on lakes and rivers are scarce. By providing detailed hydrological data in these underserved regions, SWOT helps to improve local flood prediction and risk assessments, which have traditionally relied on rough estimates due to a lack of precise data.
Furthermore, Tamlin Pavelsky, NASA’s SWOT freshwater science lead, highlights the satellite’s role in addressing the increased flooding risk from extreme weather events exacerbated by climate change. With more intense and frequent storms, like Hurricane Harvey in 2017, the need for updated engineering standards and floodplain maps becomes more pressing. SWOT’s detailed flood data enables insurers and governmental agencies such as the U.S. Federal Emergency Management Agency (FEMA) to refine their flood models. These improved models offer a more accurate forecast of flood occurrences, supporting better planning and mitigation strategies to protect lives and property against future flood risks.
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