User's guide to SAC, a computer program for computing discharge by slope-area method

Abstract

This user's guide contains information on applying the slope-area computation program, SAC. SAC can be used to compute peak flood discharges from measurements of high-water marks along a stream reach. The slope-area method used by the program is based on the U.S. Geological Survey (USGS) procedure presented in Techniques of Water Resources Investigations of the U.S. Geological Survey, book 3, chapter A2, "Measurement of Peak Discharge by the Slope-Area Method". The program uses input files that have formats compatible with those used by the Water-Surface Profile (WSPRO) computer program. The guide briefly describes the slope-area method, documents the input requirements and the output produced, and demonstrates use of SAC.

Surface-water quality-assurance plan for the U.S. Geological Survey Washington Water Science Center

“…Arcement and Schneider (1989) describe procedures for selecting the roughness coefficient. Fulford (1994) discusses the computer programs SAC, used for computing peak discharge with the slope-area method, and CAP (Fulford, 1995), used to compute peak discharge at culverts. A set of graphical user interfaces (GUIs) have been developed for SAC and CAP, referred to as SACGUI and CAPGUI, to facilitate the use of the two programs (U.S. Geological Survey, 2013https://xcollaboration.usgs.gov/wg/osw/OSWNotes/FY13 Note Archive/Forms/DispForm.aspx?ID=33).…”

csa2sac—A program for computing discharge from continuous slope-area stage data

“…SAC template file-This is a standard input file for SAC7, but with additional format restrictions. An example is in appendix 3, and it has been thoroughly documented by Fulford (1994). The name of this file is specified in csa2sac.in.…”

“…Calculation of discharge using indirect methods has been automated with the slope-area computation (SAC) program (Fulford, 1994). SAC is a widely used program within the USGS; it is easily run and displays output in a clear and convenient format, which includes flags that alert the user to shortcomings in the calculation.…”

Peak discharge, flood frequency, and peak stage of floods on Big Cottonwood Creek at U.S. Highway 50 near Coaldale, Colorado, and Fountain Creek below U.S. Highway 24 in Colorado Springs, Colorado, 2016

“…Dalrymple and Benson (1968) present the application of the slope-area indirect discharge method and provide examples of its use. The USGS computer program Slope-Area Computation Graphical User Interface (SACGUI) (Fulford, 1994;Bradley, 2012) was used to compute the peak discharge by adding the surveyed cross sections with Manning roughness coefficient assignments to the high-water marks that were previously plotted by SACGUI in the field. The slope-area method computes discharge on the basis of a uniform-flow equation involving channel characteristics, water-surface profiles, and a roughness or retardation coefficient (Dalrymple and Benson, 1968).…”