Regions and Tables for Mississippi Flood Frequency, Data through 2013 (ver. 3.0, April 2019)
Dates
Publication Date
2018-11-08
Start Date
2013
End Date
2018
Revision
2018-11-29
Revision
2019-04-25
Citation
Anderson, B.T., 2018, Regions and tables for Mississippi flood frequency, Data through 2013 (ver. 3.0, April 2019): U.S. Geological Survey data release, https://doi.org/10.5066/F7ZP45B8.
Summary
To improve flood-frequency estimates at rural streams in Mississippi, annual exceedance probability flows at gaged streams in Mississippi and regional-regression equations, used to estimate annual exceedance probability (AEP) flows for ungaged streams in Mississippi, were developed by using current geospatial data, additional statistical methods, and annual peak-flow data through the 2013 water year. The regional-regression equations were derived from statistical analyses of peak-flow data, basin characteristics associated with 281 streamgages, the generalized skew from Bulletin 17B (Interagency Advisory Committee on Water Data, 1982), and a newly developed study-specific skew for select four-digit hydrologic unit code (HUC4) watersheds [...]
Summary
To improve flood-frequency estimates at rural streams in Mississippi, annual exceedance probability flows at gaged streams in Mississippi and regional-regression equations, used to estimate annual exceedance probability (AEP) flows for ungaged streams in Mississippi, were developed by using current geospatial data, additional statistical methods, and annual peak-flow data through the 2013 water year. The regional-regression equations were derived from statistical analyses of peak-flow data, basin characteristics associated with 281 streamgages, the generalized skew from Bulletin 17B (Interagency Advisory Committee on Water Data, 1982), and a newly developed study-specific skew for select four-digit hydrologic unit code (HUC4) watersheds in Mississippi. Four flood regions were identified based on residuals from the regional-regression analyses. No analysis was conducted for streams in the Mississippi Alluvial Plain flood region because of a lack of long-term streamflow data and poorly defined basin characteristics. Flood regions containing sites with similar basin and climatic characteristics yielded better regional-regression equations with lower error percentages. The generalized least squares method was used to develop the final regression models for each flood region for annual exceedance probability flows. The peak-flow statistics were estimated by fitting a log-Pearson type III distribution to records of annual peak flows and then applying two additional statistical methods: (1) the expected moments algorithm to help describe uncertainty in annual peak flows and to better represent missing and historical record; and (2) the generalized multiple Grubbs-Beck test to screen out potentially influential low outliers and to better fit the upper end of the peak-flow distribution. Standard errors of prediction of the generalized least-squares models ranged from 28 to 46 percent. Pseudo coefficients of determination of the models ranged from 91 to 96 percent.
First release: November 11, 2018
Revised: November 8, 2018 (ver. 2.0)
Revised: April 2019 (ver. 3.0)
Reference:
Interagency Advisory Committee on Water Data, 1982, Guidelines for determining flood-flow frequency: Bulletin 17B, 183 p.
This data release provides the ArcGIS shapefiles of the four flood regions and the AEP flows derived from the methods described in the published companion product: Anderson, B.T., 2018, Flood frequency of rural streams in Mississippi, 2013: U.S. Geological Survey Scientific Investigations Report 2018–5148, https://doi.org/10.3133/sir20185148. [Supersedes USGS Water-Resources Investigations Report 91–4037.]
Revision 3.0 by Brandon Anderson on April 23, 2019. To review the changes that were made, see “VersionHistory_April2019.txt” in the attached files section.
