1. U.S. Department of the Interior U.S. Geological Survey Alabama Water Science Center 334-395-4140 jbatkins@usgs.gov StreamStats: By Kernell Ries and J. Brian Atkins A Web Site for Stream Information

2. Outline n Description of need for streamflow statistics and problems with providing them n Description of StreamStats n Implementation Process n National Status n Alabama StreamStats

3. Examples of Streamflow Statistics n 100-year flood n Average annual streamflow n Average streamflow for August n 7-day, 10-year low flow n 90-percent duration flow

4. Uses of Streamflow Statistics n Design of structures such as roads, bridges, culverts, dams, locks, and levees n Water resources planning and management, including TMDLs n Flood-plain mapping for zoning and insurance rate setting n Instream flow determinations for pollution control and habitat protection n Design and permitting of facilities such as wastewater-treatment plants, hydropower plants, and water-supply reservoirs

5. Statistics for Gaged Sites n Computed from streamflow records using standard methods n Problems: F Statistics in old reports are sometimes difficult to obtain F USGS labor cost for information requests is high F Not possible to operate gaging stations everywhere streamflow statistics are needed

6. Estimates for Ungaged Sites n Streamflow Statistics are estimated from regression equations that relate flows to basin characteristics. n Examples of basin characteristics: Basin area, slope, shape, climate, vegetation cover, degree of urbanization, geology,... n Usually developed by USGS on a State-by-State basis in cooperation with local agencies

7. Example Regression Equation n Regression equations take the form: Q 100 = 855A 0.667 n where: Q 100 is the 100-year flood flow, in cubic feet per second A is drainage area, in square miles

8. Problems with Regression Approach n Reports with equations can be difficult to identify and obtain n Delineating basin boundaries and computing basin characteristics: F Is difficult, F Demands high-level skills, F Is very time consuming F Is error-prone n Manual method can take several hours or more n GIS methods require substantial investments of time, money, and data development n Equations are often not used because of large efforts needed to determine basin characteristics

9. StreamStats Web Application n Provides estimates of streamflow statistics, basin and climatic characteristics, and other information for user-selected points on ungaged streams n Automatically measures basin and climatic characteristics for ungaged sites using GIS n Provides published streamflow statistics, basin and climatic characteristics, and other information for data-collection stations

10. StreamStats Web Page n http://streamstats.usgs.gov http://streamstats.usgs.gov F Under construction F Description of application F Links to state applications F Links to documentation

11. User Interface at Startup

12. Ungaged Site Process 1.User selects point on stream network 2.Point is transferred to a cell in a flow-direction grid derived from a DEM  DEM usually is preprocessed to conform to mapped streams and previously determined drainage boundaries 3.GIS determines drainage boundary and presents it for review in map frame 4.Boundary can be edited if errors are found 5.GIS computes drainage area and other basin characteristics 6.Basin characteristics are inserted into regression equations to compute flow estimates 7.Flow estimates appear in pop-up window with error estimates

13. Ungaged Site Selection

14. Basinwide View of Boundary

15. Zoom In to Check Boundary

16. Edit Boundary

17. Example Output for Ungaged Site

18. Data-Collection Station Process 1.USGS data-collection stations are displayed in a map frame in user’s web browser 2.User zooms in and selects a station of interest 3.Previously published information for the station is retrieved from StreamStatsDB 4.Pop-up window appears showing the information and references 5.User may also link to NWIS-Web

19. Mock-up Data-Collection Site Output

20. StreamStats Benefits n Cost — Time to delineate drainage boundaries and compute basin characteristics is reduced from hours to minutes n Accuracy — Measurement errors not introduced; some measurements much better; others about the same as manual methods n Consistency — Important for statistical validity n Accessibility — Special equipment and/or expertise not needed to obtain estimates

21. State Implementation Process n Usually done through cooperative agreements between USGS state offices and local agencies n Populate and quality assure StreamStatsDB n Generate and format GIS datasets n Test and report on accuracy of basin and climatic characteristics and equation results n Potentially develop new equations, using GIS data to measure basin characteristics n Possibly fund any required customization n USGS HQ and state office concurrence to put on Web n Full national implementation will take several years

22. National Status n 3 states fully implemented n 18 states undergoing implementation

23. Alabama StreamStats n Peak-flow equations F 2-, 5-, 10-, 25-, 50-, 100-, and 500-year peaks n Low-flow equations F 7-day low flows at 2- and 10-year recurrence intervals n Station data available n GIS data needs to be processed n Funding needed for implementation

24. n StreamStats uses cutting-edge technology to put stream information in the hands of users n Design is based on the ArcHydro Data Model and the functionality of the ArcHydro Toolset n Design is flexible and expandable n Implementation for States will be done through cooperative funding agreements n StreamStats team can provide limited support n Full implementation will likely take several years Summary