StreamStats: A U.S. Geological Survey Web Application for Stream Information
By Kernell G. Ries III, Peter A. Steeves, Jaqueline D. Coles, Alan H. Rea, and David W. Stewart
The U.S. Geological Survey (USGS) provides streamflow and other stream-related information needed to protect people and property from floods, to plan and manage water resources, and to protect water quality. Streamflow statistics provided by the USGS, such as the 100-year flood, the annual mean flow, and the 7-day 10-year low flow (7Q10), frequently are used by engineers, land managers, biologists, and many others to help guide decisions in their everyday work. For example, streamflow statistics are used for flood-plain mapping, which is used as the basis for setting insurance rates and zoning land use. Streamflow statistics also are used for dam, bridge, and culvert design; water-supply planning and management, and water-use appropriations and permitting; wastewater and industrial discharge permitting; hydropower facility design and regulation; and habitat preservation for protection of endangered species. In addition, researchers, planners, regulators, and others often need to know the physical and climatic characteristics (basin characteristics) of the drainage basins upstream from locations of interest to help them understand the mechanisms that control water availability and water quality at these locations.
Streamflow statistics can be needed at any location along a stream. Commonly, the statistics are computed from available data when they are needed at the locations of USGS data-collection stations, which include streamgaging stations, where streamflow data are collected continuously; partial-record stations, where streamflow measurements are collected systematically over a period of years to estimate peak-flow or low-flow statistics; and miscellaneous-measurement stations, where streamflow measurements usually are collected for specific hydrologic studies with various objectives. More often, however, the statistics are needed at ungaged sites, where no observed data are available to compute the statistics.
StreamStats is a map-based Web application that makes it easy for users to obtain streamflow statistics, basin characteristics, and other information for user-selected USGS data-collection stations and ungaged sites of interest. If a user selects the location of a data-collection station, StreamStats will provide previously published information for the station from a database. If a user selects a location where no data are available (an ungaged site), StreamStats will run a Geographic Information System (GIS) program to measure basin characteristics and estimate streamflow statistics for the site. These estimates assume that natural flow conditions exist at the ungaged site. In the past, it could take an experienced person more than a day to determine the estimates. StreamStats reduces the effort to only a few minutes.
StreamStats was developed cooperatively by the USGS and the Environmental Systems Research Institute, Inc. (ESRI, http://www.esri.com), and was designed for national implementation. The application consists of five major components: (1) a user interface that displays maps and allows users to select stream locations where they want streamflow statistics information (fig. 1), (2) a database that contains previously published streamflow statistics and descriptive information for USGS data-collection stations, (3) an automated GIS process that determines drainage boundaries for user-selected ungaged sites and measures the basin characteristics for those sites, (4) a GIS database that stores base-map data needed for users to locate sites of interest and other map data needed for measuring basin characteristics, and (5) an automated process that takes the measured basin characteristics for ungaged sites as input, solves regression equations to estimate various streamflow statistics, and outputs the estimates for display to the user in a Web browser window. Each of these components are described below and guidance for using the application is provided.