The USGS StreamStats application is a valuable online, mapbased tool for water resource management and engineering design. StreamStats allows users to obtain drainage basin characteristics and peak streamflow statistics at any location along a stream, gaged and ungaged. The application takes advantage of statistical relationships between stream peak flow statistics and several drainage basin characteristics, such as basin size, average slope, percent of developed land cover, and more. For example, this allows the calculation of the 1% flood event at a location where a bridge may be constructed over an unmonitored stream, or at a location where planned development will occur.
Statistics behind the existing version of Delaware StreamStats was released by USGS in 2006. Numerous high flood events from coastal storms and heavy rains as well as changes in land use and land cover have occurred since that time. Supported by DelDOT, the DGS and USGS are jointly updating the data behind Delaware StreamStats. The DGS is integrating the LiDAR-derived 2014 DEM for Delaware with elevation data from surrounding states to develop a regional, seamless DEM. This DEM is then used to update the National Hydrography Dataset (NHD) and Watershed Boundary Dataset (WBD) in order to perform the watershed analysis. Once drainage basins are delineated for streamgages in and around Delaware, over 20 basin characteristics are clipped and summarized for each basin. Those data are ingested into regression equations to develop relationships with peak streamflow statistics, and ultimately to update the online StreamStats application.