Full Equations Utilities (FEQUTL) Model for the Approximation of Hydraulic Characteristics of Open Channels and Control Structures During Unsteady Flow

# 5.14 GRITTER Command

Purpose: A generalization of the Ritter (1892) solution for the peak outflow following the instantaneous failure of a dam is computed in the GRITTER command. Discussion of this command is given in section 4.5.

LINE 1
Variables: NAME, APPTAB
Format: A8, I5
Example: APPTAB #= 731
Explanation:

 NAME must be APPTAB #=. APPTAB is the table number for the approach cross section to the dam site. This is the cross section of the prismatic, horizontal, frictionless reservoir presumed to be upstream from the dam before the instantaneous removal of the dam. In the course of the computations, this table is replaced by a table containing the Escoffier stage variable (Henderson, 1966, p. 314). Thus, the table is lost to subsequent commands. This table should not contain critical flow. Types 20, 21, 23, and 24 are acceptable.

LINE 2
Variables: NAME, CONTAB
Format: A8, I5
Example: CONTAB #= 25
Explanation:

 NAME must be CONTAB #=. CONTAB is the table number for the constricted-flow relation produced in CRITQ (section 5.4) or some similar computation. The table must give the flow for each water-surface height in the reservoir where the water-surface height is measured from the water-surface elevation in the reservoir upstream from the breach to the bottom of the reservoir.

LINE 3
Variables: LABEL
Format: A79
Example: DEPTH DISCHARGE Test of the Ritter solution.
Explanation:

 LABEL is a heading for the subsequent values of water-surface height and discharge in the reservoir before the failure and a descriptive label for the dam analyzed.

LINE 4 (Repeated as many times as needed to represent the range of water-surface heights and flows required for the analysis of various failures.)
Variables: Y1, Q1
Format: 2F10.0
Explanation:

 Y1 is the before-failure, water-surface height in the reservoir. The sequence is terminated by giving a negative value for the water-surface height. Q1 is the before-failure flow rate in the reservoir.