Active Archive of Large Floods, 1985-Present
Surface Water Watch
Satellite microwave sensors provide global coverage of the Earth’s entire land surface on a near-daily basis without severe interference from cloud cover. Using a strategy first developed for wide-area optical sensors (see article), such microwave data can be used to measure river discharge changes, river ice status, and watershed runoff.
The present Surface Water Watch uses the NASA/Japanese Space Agency Advanced Microwave Scanning Radiometer (AMSR-E) band at 36.5 GHz.. A discharge estimator is obtained for selected reaches (now numbering over 3000). This estimator is a ratio of: calibration-target radiance (for a local land parcel unaffected by the river) to measurement-target radiance (for a pixel centered over the river reach). As rivers rise or fall, reach surface water areas increase or decrease. Due to much lower microwave emission from water versus land surfaces, these changes can be measured in a consistent manner by using this ratio, which removes most other factors affecting the signal. Rating curves based on available ground-based gaging station data locally provide for conversion of this calibrated remote sensing signal to water discharge values.
Overbank flooding along even rivers of modest size produces a strong AMSR-E signal response. We are working together with the Global Disaster Alert and Coordination System (GDACS) project of the European Union's Joint Research Centre, Ispra, Italy and Dr. Son V. Nghiem at the Radar Science and Engineering Section of the Jet Propulsion Laboratory to produce a Global Flood Detection System.
Discharge is water volume moving past a measurement cross section (units of m3/sec, or, in the U.S. ft3/sec). Runoff is determined by measuring discharge over a period of time, and can be expressed in either volume units (m3), or, dividing by the watershed land area and for comparison to precipitation, mm. Satellite observation of selected river measurement reaches provide both kinds of information.
Access the results by viewing global and regional maps, or use the global summary table
Reach Status (1, Low flow or Ice-covered, 2, Normal flow, 3, Flood, 4, Major Flood) is obtained by comparison of current results to the period or record. In early 2006, this is approximately 3+ years.
Authors: G. Robert Brakenridge and Elaine Anderson, Dartmouth Flood Observatory, Dartmouth College, Hanover, NH 03755 USA.
Direct Questions to:
Bob
Brakenridge
Elaine Anderson
This work is partially supported by grants and contracts from NASA's Science Mission Directorate to Dartmouth College, Hanover NH 03755 USA (G. R. Brakenridge, Principal Investigator).
The following example shows how to cite the use of information from this site in a publication. List the principal investigators, year of data you used, map or data title or description, city and and country, institution, "digital media", and web page accessed.
Brakenridge, G.R., Anderson, E., Caquard, S., 2003, Flood Inundation Map DFO 2003-282, Dartmouth Flood Observatory, Hanover, USA, digital media, http://www.dartmouth.edu/~floods/2003282.html.
www.dartmouth.edu/~floods
©2004 Dartmouth Flood Observatory