StreamStats for South Dakota was developed in cooperation with the South Dakota Department of Transportation and East Dakota Water Development District.
South Dakota StreamStats incorporates statewide regression equations for estimating instantaneous peak flows with annual exceedance probabilities of 50, 20, 10, 4, 2, 1, and 0.2 percent. These peak flows have recurrence intervals of 2, 5, 10, 25, 50, 100, and 500 years, respectively. The report below documents the regression equations, the methods used to develop them and to measure the basin characteristics used in the equations, and the errors associated with estimates obtained from the equations. Users should familiarize themselves with this report before using StreamStats to obtain estimates of flows for ungaged sites in rural drainage basins.
Users are advised that updated at-site peak-flow estimates were developed by Sando and others (2008), and the regression equations developed by Sando (1998) do not incorporate these updated estimates. A project is underway to update the statewide regression equations based on results from Sando and others (2008). It is expected that the StreamStats application will be updated with the equations once they become available. Users are further advised that especially large statistical uncertainties can occur when estimating peak flows for the Black Hills area of western South Dakota. Additional insights regarding peak-flow characterization for especially large floods are available from Harden and others (2011), who conducted paleoflood investigations in the Black Hills area.
Click on this link to obtain general information on the South Dakota application, as well as specific sources and computation methods for basin characteristics.
Drainage Areas
South Dakota’s StreamStats application utilized the Watershed Boundary Dataset to enforce drainage boundaries. Drainage area values produced by StreamStats may be different than values published in the above report, a recent paleoflood investigation report (SIR 2011-5131), annual data reports, and in databases that pre-date the Watershed Boundary Dataset. Drainage area values produced by StreamStats are considered more accurate than previously published values, and should be used where differences occur.
For South Dakota, the drainage area values that are presented in the header information at the top of the outputs from the Estimate Flows using Regression Equations tool are actually the contributing areas, not the total drainage areas. This condition is unique to South Dakota, and was necessary because of programming limitations. Users can obtain total drainage areas by use of the Basin Characteristics tool.
Noncontributing Areas
South Dakota has varying and sometimes complex drainage patterns. Certain areas, which typically have only internal drainage, are considered noncontributing relative to the rest of the basin. To view these noncontributing areas on the map, first click on the down arrow on the right side of the Map Contents tab to the left of the map, next click on the plus sign to the left of the initial line in panel that appears, and then put a checkmark in the Noncontributing Drainage Area box.
Obtaining Flow Estimates in Noncontributing Areas
The StreamStats output will show the contributing drainage area as zero and peak flows will not be calculated when using the Estimate Flows using Regression Equations tool to estimate flows at any point within a noncontributing area. However, flow estimates from regression equations still can be obtained for points within noncontributing areas by the following process: (1) use the Watershed Delineation from a Point tool to delineate the drainage basin, (2) use the Estimate Flows using Regression Equations tool to obtain an output with the flow estimates missing, (3) use the Basin Characteristics tool to obtain a list of the available basin characteristics for the site, and (4) use the Edit Parameters and Recompute Flows tool and enter the total drainage area obtained from the output from the Basin Characteristics tool in place of the contributing drainage area to obtain correct peak flow estimates. Because waterbodies along a stream can store water and attenuate flows, it is recommended that this technique not be used to force peak flows to be computed for streams that connect waterbodies within a noncontributing area.
Related Content
Flood-frequency analyses from paleoflood investigations for Spring, Rapid, Boxelder, and Elk Creeks, Black Hills, western South Dakota
Peak-flow frequency estimates based on data through water year 2001 for selected streamflow-gaging stations in South Dakota
Techniques for estimating peak-flow magnitude and frequency relations for South Dakota streams
Related Content
- Publications
Flood-frequency analyses from paleoflood investigations for Spring, Rapid, Boxelder, and Elk Creeks, Black Hills, western South Dakota
Flood-frequency analyses for the Black Hills area are important because of severe flooding of June 9-10, 1972, that was caused by a large mesoscale convective system and caused at least 238 deaths. Many 1972 peak flows are high outliers (by factors of 10 or more) in observed records that date to the early 1900s. An efficient means of reducing uncertainties for flood recurrence is to augment gagedAuthorsTessa M. Harden, Jim E. O'Connor, Daniel G. Driscoll, John F. StammPeak-flow frequency estimates based on data through water year 2001 for selected streamflow-gaging stations in South Dakota
Numerous users, including the South Dakota Department of Transportation, have continuing needs for peak-flow information for the design of highway infrastructure and many other purposes. This report documents results from a cooperative study between the South Dakota Department of Transportation and the U.S. Geological Survey to provide an update of peak-flow frequency estimates for South Dakota.AuthorsSteven K. Sando, Daniel G. Driscoll, Charles ParrettTechniques for estimating peak-flow magnitude and frequency relations for South Dakota streams
A generalized skew coefficient analysis was completed for South Dakota to test the validity of using the generalized skew coefficient map in Bulletin 17B of the 1982 United States Water Resources Council, ?Guidelines for Determining Flood Flow Frequency.? Results of the analysis indicate that the Bulletin 17B generalized skew coefficient map generally provides adequate generalized skew coefficientAuthorsSteven K. Sando - Partners