Application of Paleoflood Survey Techniques for the Black Hills of South Dakota

Science Center Objects

Project Period: 2008-2010
Cooperators: South Dakota Department of Transportation, Federal Emergency Management Agency, West Dakota Water Development District, City of Rapid City
Project Chief: Dan Driscoll

Executive Summary

Flood-frequency analyses for the Black Hills area have large uncertainties because of several complicating factors, including (1) effects of high outliers in systematic peak-flow records, such as particularly large peak discharges caused by the extraordinary 1972 storm near Rapid City; (2) geologic influences; and (3) potential influences of topography on precipitation patterns. Methods relying on analysis of systematic data are insufficient (numbers of sites and available periods of record) to address these complications. A reconnaissance-level paleoflood study for the Black Hills area was implemented in March of 2006, as a cooperative effort between the Office of Research of the South Dakota Department of Transportation (SDDOT) and the U.S. Geological Survey (USGS). The overall conclusion of this reconnaissance-level study was that improved understanding of flood frequencies for the Black Hills region would result from implementation of future studies using established paleoflood techniques. The results of the reconnaissance-level study are presented in O'Connor and Driscoll (2007).

As a follow-up to the earlier reconnaissance-level study, USGS and SDDOT initiated a subsequent cooperative program to apply paleoflood survey techniques in selected drainages in the Black Hills area. The drainages include Elk Creek, Boxelder Creek, Rapid Creek, and Spring Creek. Several additional agencies have joined as cooperators, including the Federal Emergency Management Agency, West Dakota Water Development District, and the City of Rapid City. Final results are available in Harden and others, 2011 (SIR 2011-5131). A lay-reader summary (Driscoll and others, 2012 ) also was published in cooperation with the SDDOT.

Objectives

The primary purpose of this project is to obtain improved relations between magnitudes and frequencies for especially large peak-flow events for the selected drainages through application of paleoflood techniques.