Energy Dissipators MCQ with answer and solution

Concept

Energy dissipators are provided downstream of hydraulic structures to destroy the destructive kinetic energy of high-velocity water jets by creating a hydraulic jump inside a specially tailored basin.

Step-by-step solution

Glacis - it is a sloping floor that helps in transitioning flow but is not a basin itself. Syphon - it is a type of cross-drainage work used to carry canal water under a stream. Stilling basin - a concrete structure specifically designed to form a hydraulic jump and dissipate energy. Aqueduct - a cross-drainage work where a canal flows over a natural drainage.

Explanation

A stilling basin is a structured concrete tank or pool built downstream of hydraulic structures (like spillways orweirs) specifically designed to dissipate the high kinetic energy of flowing water through hydraulic jumps, protecting the riverbed from severe erosion.

Why the other options are wrong

A: Glacis is a sloping apron used to convey water safely but does not primarily dissipate energy by forming a controlled jump like a basin. B: Syphon is a cross-drainage structure. D: Aqueduct is a cross-drainage structure carrying canal water over a drainage.

Shortcut

Remember that 'stilling' implies calming or slowing down water, making stilling basins the primary energy dissipators.

Common mistake

Confusing a glacis (sloping surface) with a stilling basin (the energy-dissipating pool itself).