Short Answer:

The different types of spillways used in dams include ogee spillway, chute spillway, side channel spillway, shaft spillway, and siphon spillway. Each type is selected based on the dam’s design, location, and expected water flow.

Spillways are important safety structures in dams that allow excess water to be discharged in a controlled manner. The choice of spillway type ensures smooth water release without causing damage to the dam or downstream areas, especially during floods or heavy rainfall.

Detailed Explanation

Different types of spillways used in dams

A spillway is a critical structure in dam engineering designed to safely discharge excess water from a reservoir. Depending on the topography, hydrological conditions, and dam type, civil engineers choose from various spillway designs. These spillways manage water flow during floods and prevent overtopping, which could otherwise lead to dam failure.

Each spillway type has its own design features, advantages, and suitable usage conditions. Selecting the right type ensures effective flood control, long-term dam safety, and environmental protection.

Types of Spillways Used in Dams:

Ogee Spillway:

Also known as a overflow spillway.
Shaped like an “S” curve, following the natural flow of water.
Commonly built into concrete gravity dams.
Handles large volumes of water efficiently.
Offers smooth flow and reduces pressure on the dam wall.

Chute Spillway:

Also called open channel spillway.
Water flows down a steep concrete-lined channel built beside the dam.
Suitable for earthfill and rockfill dams that cannot allow water to overflow the crest.
Includes energy dissipators at the end to slow water.

Side Channel Spillway:

Located on the side of the reservoir instead of directly in front of the dam.
Water enters the side channel and then flows along it before being released.
Useful when space in front of the dam is limited.
Requires longer channels and more maintenance.

Shaft Spillway:

Also known as morning glory spillway due to its funnel-like shape.
Water enters through a vertical shaft and flows down into a tunnel.
Ideal for narrow valleys and deep dams.
Compact in design but requires careful engineering.

Siphon Spillway:

Uses the siphon principle to draw water once it reaches a specific level.
Water is pulled over the crest and down through a closed pipe.
Automatically starts and stops the flow depending on reservoir level.
Useful for controlled discharge but needs venting systems.

Selection Factors for Spillway Type:

Topography and geology of the site
Design and height of the dam
Expected flood volume and intensity
Space availability for constructing spillway channel or shaft
Ease of maintenance and cost

Engineers use these factors to choose the best type of spillway that matches the dam’s structure and ensures safe operation during high inflow events.

Application in Civil Engineering Projects:

Ogee and chute spillways are widely used in concrete and earthen dams.
Shaft spillways are used where space is limited.
Side channel spillways are selected for long, narrow valleys.
Siphon spillways are applied in automatic level-control systems for small dams or irrigation tanks.

Proper design, regular inspection, and timely maintenance of spillways are essential for the safety and durability of dams.

Conclusion:

There are several types of spillways used in dams, including ogee, chute, side channel, shaft, and siphon spillways. Each is designed for specific site conditions and dam types to safely manage water flow. The right spillway ensures the dam can handle excess water during floods while protecting the structure and nearby areas.