Garnett’s diagrams (graphical aids) are traditionally used to solve the design equations of a canal according to which regime theory?
-
ALacey’s theory
-
BKennedy’s theory
-
CGibb’s theory
-
DLindley’s theory
-
ETractive force theory only
Answer
Correct Answer: Kennedy’s theory
Explanation
Introduction / Context:Before widespread digital computation, designers relied on graphical tools to solve iterative canal-design equations. Garnett’s diagrams are classic aids connected with one of the two well-known regime design approaches: Kennedy and Lacey.
Given Data / Assumptions:
- Design target is a non-silting, non-scouring canal section.
- Charts/nomograms attributed to Garnett are referenced.
- Question asks which theory they support.
Concept / Approach:
Kennedy’s theory centers on critical velocities to prevent silting/scour and involves interdependent variables (depth, velocity, slope). Garnett produced graphical charts to streamline these computations, allowing designers to read off solutions for given discharge and silt grade.
Step-by-Step Solution:
Identify the design framework (Kennedy) where critical velocity ratios are used.Recall that Garnett’s diagrams plot relationships to bypass algebraic iteration.Therefore, they are tied to Kennedy’s method.Verification / Alternative check:
Many irrigation texts list “Garnett’s diagrams for Kennedy’s design” alongside regime tables.
Why Other Options Are Wrong:
Lacey’s method uses a different set of empirical relations; Gibb’s and Lindley’s are not the standard attributions for Garnett’s charts.
Common Pitfalls:
Conflating graphical tools across theories; overlooking that each regime theory has its own calibration and parameters.
Final Answer:
Kennedy’s theory