What does an outlet do?

Delivers water from a distributary or minor to the water course of a chak

Takes water from a river into the main canal

Drains excess water from the field

Why should an outlet need only a low working head?

So that the command area is not reduced

In a table comparing the two types, what is the main difference in discharge dependence?

Semi-modular depends on distributary level only, non-modular on both distributary and water course levels

Non-modular depends on distributary only

Both depend on water course only

Semi-modular depends on both levels

Which statement is correct about non-modular versus semi-modular outlets?

Non-modular needs lower head but gives poorer equity and is easier to tamper with

Non-modular needs higher head and gives better equity

2068 Chaitra (old course) · 1+2+3 marks

Outlet, requirements, modular vs semi-modular

Short answer

An outlet is a small structure delivering water from a distributary to a water course. Requirements: simple, tamper-proof, low working head, draws fair silt share, equitable distribution, insensitive to water course level. Non-modular outlets depend on both distributary and water course levels (e.g., submerged pipe); semi-modular outlets depend only on distributary level (e.g., free pipe, AOSM).

What is outlet? Write down the requirements that an outlet should fulfill. Distinguish clearly between non modular and semi-modular outlet.

Outlet (1 mark)

An outlet is a small structure that takes water from a distributary or minor and delivers it to the water course of a chak (farm area).

Requirements of an outlet (2 marks)

Simple, robust and cheap, with no moving parts and little maintenance.
Tamper-proof, so the discharge is fixed.
Low working head so the command is not reduced.
Draws its fair share of silt with the water.
Gives equitable distribution (proportional or sub-proportional).
Insensitive to the water level in the water course.

Non-modular vs semi-modular (3 marks)

Point	Non-modular outlet	Semi-modular outlet
Discharge depends on	Levels in both distributary and water course	Level of distributary only
Water course effect	Yes, level changes alter discharge	None (free flow), if min. head available
Flow condition	Drowned or submerged	Free jet
Examples	Open sluice, submerged pipe	Pipe (free), Kennedy gauge, open flume, adjustable orifice (AOSM)
Tampering	Easy	Less
Equity of distribution	Poor	Better
Working head	Low	Higher

✓ Answer checked by Claude Opus 5.5 (high effort)

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All Irrigation and Drainage Engineering chapter 7 questions →

Outlet, requirements, modular vs semi-modular

Outlet (1 mark)

Requirements of an outlet (2 marks)

Non-modular vs semi-modular (3 marks)

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