Types of Spillways

Spillway is considered as the one of the primary structural components of dam that pours the water back into the river with the purpose of not damaging the dam. Given below, the detailed lists of various types of spillways.

Usually, spillways are categorized into two sections like overflow & channel type depending on where it is positioned. These two main types are again subcategorized as below:

Overflow type spillway
The Overflow type spillway is the most essential section of the dam and operates as per the dam but there is no hazard if the water pours over it. Ogee Spillway is considered as the most suitable overflow type spillways.

Ogee Spillway:
It belongs to overflow type spillway which contains a controlled weir and is ogee-shaped(S-shaped) in profile. It is designed in a manner that it pursues the lower surface of a horizontal jet rising from a sharp crested weir. The pressure at the ogee crest persists atmospheric at the design head. At lower head, the pressure on the ogee crest turns to be positive that leads to the backwater effect and this backwater effect minimizes the discharge during the higher head pressure on the crest and turns to be negative producing backwater effect to upsurge the discharge.

Channel type spillway
It belongs to the category of spillway that is separated from the dam. Given below, some of the most recognized channel type spillways:

Chute Spillway:
It is also called Trough Spillway. The purpose of Chute Spillway is to withstand injury to the valley walls that could create risks in the dams. It includes steeply sloping open channel created with reinforced concrete slab. The Spillway often contains constant width, but is generally compressed for economy and then expanded adjacent the end to minimize the discharging velocity.

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