Spillways and its types

What is Spillway? Discuss the various types of spillways.

Spillways-

Spillways are provided to discharge the flood water during rainy season when water level rises above the maximum level of reservoir.

The main function of spillways is to save dam from damage.

Types of spillways-

1)    Solid gravity spillway

2)    Chute spillway

3)    Side channel spillway

4)    Saddle spillway

5)    Siphon spillway

1) Solid gravity spillways-

a)     These types of spillways are provided to gravity dams.

b)    Excess of water flows over the crest.

c)     At the end of spillways bucket is provided to destroy kinetic energy of water.

2) Chute spillways-

a)     It is similar to solid gravity spillway except the end channel of spillway is provided to meet river channel.

b)    This type of spillway is constructed when valley is narrow.

3) Side channel spillway-

a)     This type of spillway is provided when valley is to narrow.

b)    In this type of spillway side channel is provided to discharge excess of water.

c)     The excess of water in the side channel is used in cannels or again meet to river.

4) Saddle spillways-

fig. Saddle spillway

fig. Saddle spillway

a)     This type of spillway is constructed when all above spillways are not favourable.

b)    When there is any natural depression or saddle near the dam then it is used as spillway.

5) Siphon spillways-

fig. Siphon spillways

a)     It is constructed in the form of siphon.

b)    When water level of reservoir rises above full reservoir level (FRL) it enters into spillways and discharged through siphon.