Montague type fall in canals: What is the characteristic form of the glacis provided in a Montague fall?

Introduction / Context:
Falls are drop structures in canals used to control bed levels and dissipate excess energy safely. Several standardized fall types exist in Indian practice, including Montague, Inglis, and Sarda types, each with a characteristic glacis geometry aimed at stable hydraulic performance and reduced scour risk.

Given Data / Assumptions:

• Montague fall referenced without special site constraints.
• Classification asked is based on standard textbook definitions.
• Glacis shape identifies the fall type.

Concept / Approach:
A glacis is a sloping apron downstream of a crest that controls the hydraulic jump location and energy dissipation. The Montague fall is classically described with a straight glacis; this contrasts with other forms such as parabolic glacis (e.g., in Inglis fall) or purely broad-crested drops.

Step-by-Step Solution:
1) Identify fall name and its defining feature.2) Match to geometry: Montague → straight glacis.3) Select the option that directly states a straight glacis.

Verification / Alternative check:
Standard hydraulics and canal works references associate Montague falls with straight glacis profiles developed for predictable jump formation and manageable scour downstream with appropriate protection works.

Why Other Options Are Wrong:

• Circular glacis: not the named feature of Montague fall.
• Parabolic glacis: associated with other fall types (e.g., Inglis).
• No glacis or free overfall only: not the characteristic Montague configuration.

Common Pitfalls:

• Memorizing names without linking to the defining glacis geometry.
• Confusing Montague with glacis-less drops or with parabolic profiles.

Final Answer:
A straight glacis is provided.