Skip Links

USGS - science for a changing world

Fact Sheet 2004-3028

SAM 2.1—A Computer Program for Plotting and Formatting Surveying Data for Estimating Peak Discharges by the Slope-Area Method

By Jon E. Hortness

Thumbnail of and link to report PDF (687 kB)Summary

The U.S. Geological Survey (USGS) measures discharge in streams using several methods. However, measurement of peak discharges is often impossible or impractical due to difficult access, inherent danger of making measurements during flood events, and timing often associated with flood events. Thus, many peak discharge values often are calculated after the fact by use of indirect methods.

The most common indirect method for estimating peak discharges in streams is the slope-area method. This, like other indirect methods, requires measuring the flood profile through detailed surveys. Processing the survey data for efficient entry into computer streamflow models can be time demanding; SAM 2.1 is a program designed to expedite that process.

The SAM 2.1 computer program is designed to be run in the field on a portable computer. The program processes digital surveying data obtained from an electronic surveying instrument during slopearea measurements. After all measurements have been completed, the program generates files to be input into the SAC (Slope-Area Computation program; Fulford, 1994) or HEC-RAS (Hydrologic Engineering Center-River Analysis System; Brunner, 2001) computer streamflow models so that an estimate of the peak discharge can be calculated.

First posted 2004

For additional information contact:
Director, Idaho Water Science Center
U.S. Geological Survey
230 Collins Road
Boise, Idaho 83702

Part or all of this report is presented in Portable Document Format (PDF); the latest version of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge.

Suggested citation:

Hortness, J.E., 2004, SAM 2.1—A computer program for plotting and formatting surveying data for estimating peak discharges by the slope-area method: U.S. Geological Survey Fact Sheet 2004-3028, 6 p.



Input Data

High-Water-Mark Data

Cross-Section Data

Output Data Files


References Cited

Accessibility FOIA Privacy Policies and Notices logo U.S. Department of the Interior | U.S. Geological Survey
Page Contact Information: Contact USGS
Page Last Modified: Tuesday, November 29, 2016, 06:01:48 PM