Mapping Inundation at USGS Stream Gage Sites: A Proof of Concept Investigation Principal Investigator:

The USGS National Water Information System (NWIS) provides real time access to stream gage observations of river stage and discharge at over 7,000 locations nationwide. During periods of potential or actual flooding, NWIS provides invaluable information to hydrologists, emergency managers, local government, business, industry, farmers, and the general public. Stage and discharge are available in tabular form or plotted as hydrographs to illustrate current variations in flow compared with historical median values. Such data products are used to track the evolution of rapidly evolving river conditions that pose a threat to lives, property, and infrastructure. Thanks to the availability of The National Map’s digital elevation, orthoimagery, and vector feature data, USGS can potentially add significant value to NWIS offerings by providing geospatial information products to accompany tabular and graphical summaries. Inundation patterns, based on the combined use of streamflow and elevation data, could be displayed over orthoimages or vector features (transportation, hydrography, administrative boundaries, etc) to permit visualization of high water conditions in the vicinity of a stream gage. Map products of this kind would more clearly illustrate the consequences of high flows to a broad audience of users