Surface Water Watch


G. R. Brakenridge and A. J. Kettner


Flood Display

Light gray: Satellite record of flooding or high water obtained by DFO, 1993-Present (all sensors). Red: Currently observed water, from NASA MODIS sensors (two week accumulation period). Blue: Reference water from Landsat data, Global Surface Water Explorer. This masks other water layers underneath.

Click on colored dots to retrieve River and Reservoir Watch daily values.

For previous dates, access this directory.


Low Water Display

Blue: Today's two week MODIS 250 m surface water accumulation. This is above a specially-prepared MODIS 250 m reference water layer (yellow). Visible yellow is currently dry land that is often under water.

Click on colored dots to retrieve River and Reservoir Watch daily values.

For previous dates, access this directory.



Since late 1993, satellite data have been obtained by the Dartmouth Flood Observatory, processed to detect water/land boundaries, and analyzed to produce flood inundation limits. In 2011, NASA NRT Global Flood Mapping began providing daily global surface water information at 250 m spatial resolution. This provides fully automated currently observed water, using running forward 2 week accumulations, updated each day. This information is used in both displays.

DFO creates annual maximum water extents from the NASA Global Flood Mapping project: by accumulating into one annual file all of the daily files for each year. These and all flood events individually mapped since 1993 are included in the light gray areas shown in the upper map. This is valuable information for prediction of future flood hazard.

Much larger scale versions in Geotif format are available and can be provided as a daily data service. Please contact the Flood Observatory staff: Robert. Brakenridge @ or Albert. Kettner @


Click here for access to the automated daily MODIS-derived .shp file GIS record of surface water. Data from the Global Surface Water Explorer is also included in the upper display. These are based on Landsat data at a spatial resolution of 30 m (Jean-Francois Pekel, Andrew Cottam, Noel Gorelick, Alan S. Belward, High-resolution mapping of global surface water and its long-term changes. Nature 540, 418-422, 2016). NASA Shuttle Water Boundary Data (SWBD) surface water extent (90 m resolution) is derived from NASA's 11-day February, 2000, SRTM mission and is included as part of the reference water mask (blue in the upper display). Finally, since 1993, DFO produced many flood extent files through mapping of individual floods using various sensors. These are included in the light gray layer.

River Watch Measurements (clickable colored dots above):

At selected locations, a time series of satellite microwave-based river discharge or reservoir area measurements are available from the Flood Observatory. See River Watch Global Display for more information. Yellow dots: low flow. Blue dots: normal flow. Purple dots: moderate flooding (>1.5 year recurrence interval). Red dots, major flooding (> 5 year recurrence interval).

Creative Commons License
This work, web site, and associated data are by G. R. Brakenridge and A. J. Kettner and are provided for use under the terms of a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.


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