This document summarizes different types of spillways and gates used in dams. It defines spillways as structures that safely release flood waters from dams. The main types of spillways discussed are chute, ogee, free fall, side channel, shaft, and siphon spillways. Ogee spillways are commonly used in gravity dams as they cause less downstream erosion. The document also describes various types of gates used to control water flow over spillways, including vertical lift gates, taintor/radial gates, Reynolds gates, and Visvesvaraya gates. Visvesvaraya gates were the first automatic spillway gates designed using counterweights to open and close the gates during floods and normal water levels.

1. By
prof. Hole G.R.
M.E(Hydraulics)
Spillways and Gates

2.  Spillways are structures constructed to provide safe release
of flood waters from a dam to a downstream side.
Definition

3.  Approach Facility allow flow enter in to Spillway
 Discharge Facility it collect water from approach facility and
Discharged to Outlet Facility
 Outlet Facility it helps to dissipated Energy of water.
COMPONENTS OF SPILLWAY

4. within the body of the dam
At one end of it
Entirely away from it
Location of spillway

5.  The inflow design flood hydro-graph
 The type of spillway to be provided and its capacity
 The hydraulic and structural design of various components and
 The energy dissipation downstream of the spillway.
Parameters considered in Designing Spillways

6.  A Spillway designed to safely pass the inflow of flood
occurred higher than Design flood is called Emergency
Spillway.
 The location of Emergency Spillway is higher than Main
Spillway.
 The top of Emergency spillway is kept below the TDL and
above the HFL.
Emergency Spillway

7. Free fall spillway
Ogee Spillway
Chute Spillway
Side Channel Spillway
Shaft Spillway
Siphon Spillway
Types of Spillways

8. Geometrically it is a S-shaped.
There is no gap between spillway surface and nappe.
The Ogee spillway is generally provided in Gravity dams.
There is less erosion of D/S bed of river.
Ogee Spillway

10.  This is a simplest type of spillway.
 The structure is small bund or rectangular vertical wall type.
 Water is freely fall from top of spillway and vacuum is
created as there is gap between nappe and wall of dam so
vacuum is created .
 As water falls freely so velocity of falling water is high which
causes erosion of D/S bed of river.
 Generally it is provided in Arch Dam.
Free Fall Spillway

11.  It is a steep sloped open
channel .
 It is provided to the sides of
dam.
 Generally provided in Earth
/ Rock fill Dam.
 It is suitable for any type of
foundation as it is lighter
than other type.
Chute Spillway

12.  In this type of spillway water is turned in to 90 deg and
running parallel to crest of dam.
 This type of spillway provided when there is no space for
providing spillway in body of dam.
 Flow of spillway can be diverted in to canal or D/S side of
river
 Suitable only when-
1.Earth and rock fill dam.
2.Direct overflow is not possible.
Side Channel Spillway

14.  Water is not allowed to flow over crest of dam.
 Water is released by syphon action.
 When water level is in reservoir rises above the NPL, water flow over the
crest and symphonic action takes place.
 There are two types of syphon spillway
1. saddle syphon
2. volute syphon
Syphon Spillway

15.  It provided when there is no adequate space for other type of spillway.
 In this spillway water from reservoir enters in to vertical shaft which
conveys this water in to horizontal tunnel which finally discharges in to
D/S of dam.
 Components of shaft spillway
- over control weir
- vertical control
- closed discharge channel
Shaft Spillway

16.  It is the structure which is located above the crest of spillway to
control or store surplus water in dam.
 The gates are fitted in steel frames and frames are fitted in piers.
Advantages of Gates:-
1.Saving ht of the dam.
2.Give more useful storage for same ht.
3.Ruduction in ht of spillway.
Dis-advantages of Gates:-
1.Installation of gates involves additional cost.
2.As moving part is more frequent maintenance is required.
SPILLWAY Gates

17. 1. Vertical lift Gate.
2. Taintor / Radial Gate.
3. Reynolds Gate.
4. Visvesvaraya Gate.
Vertical lift Gate
 Rectangular in shape and made from steel frame.
 These are fitted in steel frame fitted in piers.
 It moves vertically up and down.
 These gates operated with the help of iron chain and pully
arrangement.
Types of Gates

19.  The shape of gate is sector of circle so that’s why it is
called as radial gate.
 Used when span between two piers is large varing from 4
to 15 m.
 Curved face of gate support water.
 It is properly braced by steel frame and mounted on
horizontal shaft .
 Gate can be operated by means of chains and ropes.
 Because of circular shape ,it require less effort for lifting.
Taintor / Radial Gate

21. It is fixed roller automatic gate and designed by Mr.
E.K.Reynolds , he was S.E at PWD Bombay.
Each gate is connected to one counter weight by chains passing
over pulley.
This counter weight is placed in a deep well constructed under
each pier.
This Well is connected to U/S water level by inlet pipe. When
water levels rises to F.R.L., The counterweight moves up, the
gate sinks below the weir crest, allowing the flood water to
pass over spillway.
 After usual flood , the water in the well is drained out and the
gate will moves up and rest on the crest, thus closing the span
Reynolds Gate

22. Reynolds Gate

23. Visveshwarya Gate

24. Visveshwarya Gate
 This gate are fixed roller automatic Gate
 Such 88 Gates Firstly Designed by Sir. Visveshwarya in 1906 on Khadakwasla
Dam.
 There are 11 sets each having 8 Gates. Out of 8 Gates 4 are Heavy Gates and 4
are Light Weight Gate.
 2 Heavy are connected to Counterweight and Each Light weight gates are
connected to adjacent Heavy Gates by means of pulleys.
 Counter weights are placed in Closed chamber having inlet at F.R.L level. As
the water levels increases beyond F.R.L level, water start entering to the
Chamber by inlet pipe.
 As the level in chamber increases, due to buoyancy the weight of counterweight
are start Decreasing and the Heavy gates slides down below crest of spillway
and Light Weight are Slides up as it is connected to Heavy Gates. This is Open
condition of gates occurred during flood.
 As Level of reservoir fall below F.R.L., The water entering in to chamber are
stopped and water from chamber is drained out due to which wt. of
Counterweight increases and Heavy Gates Moves Up and Light Weight Moves
Down and Rest on Sill Level. This is the Closed Situation of Gates.