The USGS is developing a Dynamic Surface Water Extent (DSWE) product that maps surface water as detected in cloud-free, shadow-free, and snow-free pixels collected by Landsat sensors over any location in the United States and its territories. When more than one Landsat satellite is in operation, images may be collected every 8 days. Given such frequency and a spatial resolution of 30 m for much of the past 30 years, the DSWE will provide information on the temporal and spatial patterns of surface water extents in lakes, rivers, and wetlands. The uncertainties associated with DSWE estimates given variations in adjacent land cover and water feature size are important considerations for product usefulness and appropriate application. The accuracy of DSWE provisional data are now being evaluated at over 40 sites across the conterminous United States, Alaska, Hawaii, and Puerto Rico through comparison with surface water extent data captured on the ground and from various remote sensing systems besides Landsat. DSWE provisional data are also being collaboratively applied to evaluate their utility for various scientific and resource management activities. The DWSE will be a valuable addition to the Landsat Science Products portfolio and will prove useful for a variety of scientific, resource management, and educational activities.
Lake Mead Dynamic Surface Water Extent data derived from Landsat 5 (Left) and Landsat 7 (right) summer images captured nearly 30 years apart. Significant differences in Lake Mead aerial extent caused by variations in climate and water demand are obvious. Such lengthy records of surface water variations are useful for science, resource management, and education. Note: Cross hatches visible in the right image are missing data due to The Landsat 7 scan line corrector failure.