NEAR REAL TIME RIVER DISCHARGE OBSERVATION AND FLOOD INUNDATION MAPPING USING SATELLITE REMOTE SENSING PRODUCTS

Three related advances in Satellite Remote Sensing (SRS) of Near Real Time (NRT) river water discharge and flood are presented:

1. The Dartmouth Flood Observatory (DFO), in collaboration with the European Commission’s Joint Research Center, launched the 3^rd version of its “River Watch” data service. River Watch use satellite microwave sensors (TRMM, AMSR-E, AMSR-2, and GPM) that provide daily global coverage to monitor river discharge at selected gauging sites. Rating curves relating site surface water area (and thus flow width) to water discharge are accomplished using a global hydrology model (WBMplus). Once a River Watch site is established, daily discharge observations are provided, as well as flow statistics, between 1998 and the present (updated daily). This approach is an innovative ways of incorporating remote sensing and numerical models data streams into useful hydrologic knowledge in ungagged rivers.

2. DFO NRT flood inundation mapping portal is based on NASA Goddard Space Flight Center automated MODIS processor. Daily water extent maps are provided globally and maps of current major flood events are featured at the DFO home page. A new procedure of pre-compiling flood maps based of past events is showcased. These maps provide a library of past flood events associated with selected River Watch sites. A repository of inundation maps of past flood events in the U.S. is currently in development in collaboration between DFO, the Surface Dynamics Modeling Lab and the newly established NOAA National Water Center (NWC). This project utilizes a suit of satellite platforms (MODIS, Landsat, SAR) and classification techniques to generate a web-based portal for medium- and high-resolution flood maps. Among other potential applications, the repository is intended as a key resource for calibrating and validating hydraulic models as part of a new hyper-resolution national flood prediction system currently under development at the NWC.

3. A new procedure for estimating water depth from SRS flood extent data is introduced. This new GIS-based algorithm is based on extracting the elevation of cells at the margins of an inundation extent polygon (from an underlying DEM) and inheriting these downslope. Here we present comparison between the new algorithm and depth estimations using hydraulic modeling of various flood events.