2 Theoretical Basis for
SAM.hyd Calculations
Purpose
The purpose of the hydraulics module, SAM.hyd, is to provide hydraulic
design engineers with a systematic method, based on state-of-the-art theory, for
rapidly calculating channel size in both fixed and mobile boundary streams.
General
SAM.hyd solves the steady state, normal-depth equation to transform complex
geometry into composite, 1-dimensional hydraulic parameters. The program can
solve for either depth, width, slope, discharge, or roughness. It allows roughness
to be calculated by several different roughness equations within the same cross-
section.
SAM.hyd contains an analytical procedure for calculating stable channel
dimensions in either sand bed or gravel bed streams. It is based on the Brownlie
equations for sediment transport and bed roughness. This calculation provides a
table of channel width-depth-slope dimensions which are in equilibrium with the
inflowing sediment load. Channel dimensions at minimum stream power are also
calculated.
SAM.hyd provides the option of calculating riprap size as described in EM
1110-2-1601, "Hydraulic Design of Flood Control Channels" (USACE 1991,
1994) or through testing the results of the normal depth calculations against the
Shield's Diagram for particle stability. The 13 standard riprap sizes from EM
1110-2-1601 are coded into SAM. The user can also specify quarry run riprap.
SAM.hyd offers two procedures for calculating riprap. When flow velocity
and depth are known, the riprap size is calculated directly. When water
discharge and cross section are given, riprap size is determined by a more
complicated calculation since n-value becomes a function of riprap size.
6
Chapter 2
Theoretical Basis for SAM.hyd Calculations
Previous Page
