New Satellite to Revolutionize Understanding and Management of Surface Water

In the near future, NASA and CNES, the French space agency, will debut a new satellite that many researchers believe could be a game changer in understanding and managing Earth’s greatest resource: water.

SWOT – short for Surface Water and Ocean Topography – will “see” 90 percent of our planet and provide the first global inventory of its surface waters. Targeted to launch in 2020, SWOT’s 120-km-wide swath altimetry (multiple altimeters on one platform) will capture the surface water extent and elevation of flood waters, rivers, lakes, and ocean and near-coastal eddies with unprecedented accuracy. It will also provide the first ever simultaneous measurements of the height and width of these surface waters.

SWOT will support important research objectives for ocean circulation and climate, global sea level changes, decadal variability (El Niño and La Niña events), and coastal variability and impacts. Ocean currents are an important mechanism by which heat is moved around the planet, thereby influencing patterns of rainfall and temperature change. More fully documenting these currents may improve weather and marine forecasts. In addition, new insights into ocean circulation can benefit the commercial fishing industry, keep off-shore oil production facilities safer, and optimize commercial and noncommercial shipping operations.

Data from SWOT is also expected to contribute to the management of water resources over land, informing activities such as reservoir operations, irrigation scheduling, and flood and drought management.  These measurements will help scientists assess changes in storage in lakes and reservoirs and discharge in rivers and will further our understanding of flood frequency, water availability, ecosystem impacts, climate change effects on surface water, and more.

Of all the potential benefits from these advanced capabilities, perhaps the most compelling application will be seen in regions that lack sufficient water-level gauges.  Water-level data collected along some rivers is sparse, and even if water levels are well-gauged the data is not often shared among countries. Using satellite data to understand the behavior of rivers in vast tracts of land where there is insufficient ground data has tremendous implications for the millions of people living in the Nile, Niger, Mekong, Indus, Ganges-Brahmaputra-Meghna (GBM), Salween, and Zambezi river basins. These areas host some of the world’s largest population centers, yet in the case of flooding, people living there are often unaware of impending danger. That’s because regional officials lack the key information they need about rivers and surrounding landscapes to determine how nature and humans are altering the movement of surface water. SWOT will help estimate more accurately the discharge of water feeding floods downstream.

SWOT data can be used to calibrate models, or it can be assimilated into models to predict the amount of surface water, where it will accumulate, and how fast the water levels will change.

Earth is a complicated, dynamic system we do not yet fully understand. SWOT will deliver critical global data that will provide insights into the dynamics of our planet, and could help people worldwide cope with its changes. 

NOTES: 
NASA will provide the launch vehicle for SWOT, and NASA and CNES are jointly developing SWOT’s instrument payloads. The Jet Propulsion Laboratory is managing NASA's role in the SWOT mission.