BS ISO 9123:2017

Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Symbols and abbreviated terms
5 General considerations
6 Unit-fall method
7 Constant-fall method
8 Variable-fall method
9 Rating curves and tables
10 Method of computation
11 Periodic checking of stage-fall-discharge ratings
12 Extrapolations
13 Evaluation of uncertainty in the
   stage-fall-discharge relation
Annex A (informative) - Multiple least squares
        regression - Matrix representation
Bibliography

Describes methods for determining stage-fall-discharge relationships for a stream reach where variable backwater occurs either intermittently or continuously.

This document specifies methods for determining stage-fall-discharge relationships for a stream reach where variable backwater occurs either intermittently or continuously. Two gauging stations, a base reference gauge and an auxiliary gauge are required for gauge height measurements. A number of discharge measurements are required in order to calibrate the rating to the accuracy required by this document.

The preparation of rating curves is not described in detail in this document.

NOTE For a more detailed description of preparing rating curves, see the methods described in ISO1100‑2 .