component parts of a weir

Component parts of a weir :-

Body wall of weir:- 

• It is a wall which is constructed to raise the water level on u/s
• To raise water level on u/s
• Strong enough to resist water pressure
• Strong enough to resist uplift pressure

Upstream Apron:-

• Protect weir from erosive forces during floods
• Length of apron depends upon discharge in river and length of weir 
• Strong enough to withstand downward water pressure
• Strong enough to prevent any leakage in the sub soil

 Downstream apron:-

• To reduce the kinetic energy of  water
•  Length depends upon height of fall of water nature of soil discharge in river
• Apron is extended up to the point where there is no scope for erosion
• Should have sufficient thickness to resist uplift pressure

Upstream curtain wall:-

• To reduce uplift pressure
• Length depends on nature of sub soil
• To increase length of the creep
• To reduce exit gradient

Downstream curtain wall:-

• Protect downstream flow from uplift pressure.
• Strong enough to resist kinetic energy of water increase length of creep

Creep:-

• Top of  weir is called crest 
• Strong enough to resist excessive pressure during floods
• Shutter will laid flat during floods over the  crest 

Shutters:-

• Provide on the crest
• Can be raised during flood
• Strong enough to resist water pressure