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A
SEMINAR REPORT
ON
TYPES OF SPILLWAYS
THE PROJECT
THIS IS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE
AWARD OF DEGREE

BACHELOR OF TECHNOLOGY
IN
CIVIL ENGINEERING
SUBMITTED
By
DEBASIS BEHERA
ROLL NO-401038
UNIVERSITY REGISTRAYION NO: -2101105070
B. TECH 4TH YEAR {CIVIL ENGINEERING}
{Under the guidance of}
MR SUBRAT KUMAR NAYAK

INDIRA GANDHI INSTITUTE OF TECHNOLOGY, SARANG

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Approval of the Viva-Voce Board

Certified that the seminar report entitled "TYPES OF SPILLWAYES",
submitted by Student DEBASIS BEHERA to the Indira Gandhi Institute of
Technology Sarang, for the Bachelor of Technology, has been accepted by the
internal examiners and that the student has successfully presented his work
held today.

Mr. SUBRAT KUMAR NAYAK Dr. GOUTAM KUMAR POTHAL

(GUIDE) (HOD, CIVIL ENGG.)
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CERTIFICATE
This is to certify that the thesis entitled

“TYPES OF SPILLWAYS”
SUBMITTED BY

DEBASIS BEHERA

In partial fulfilment of the requirements for the award of Bachelor

of Technology degree in the department of civil engineering at
Indira Gandhi Institute of Technology, Sarang is an authentic work
carried out by them under my supervision and guidance. To the
best of my knowledge, the matter embodied in this project review
report has not been submitted to any other University/ Institute for
award of any degree.

Mr.subrat kumar nayak

GUIDE
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ACKNOWLEDGEMENT

This research project could not have been possible without the
support of many people. The author wishes to express his
deep sense of gratitude to his supervisor, designation: -
MR. SUBRAT KUMAR NAYAK

 Department of civil engineering who was abundantly helpful

and gave invaluable assistance, support, guidance.
 The author would like to place un record his sincere thanks to
all faculty members of civil engineering for their help and
encouragement. The author would like to express his thanks
to Dr. GOUTAM KUMAR POTHAL, Professor & Head,
Department of
Civil Engineering, Indira Gandhi Institute of Technology,
Sarang.
for providing the facilities for successful completion of this
work.
➢ would like to sincerely thanks the lab assistants
and last but not the least the author expresses his thanks to all
his friends and colleagues for their constant help.

DEBASIS BEHERA---2101105070
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CONTENTS

 CERTIFICATE OF APPROVAL

 CERTIFICATE

 DECLARATION

 ACKNOWLEDGEMENT

 TABLE OF CONTENTS

 LIST OF FIGURES

 ABSTRACT
 INTRODUCTION

 TYPES OF SPILLWAYS

 STRAIGHT DROP SPILLWAY

 OVERFLOW SPILLWAL

 SIDE CHANNEL SPILLWAY

 OPEN CHANNEL SPILLWAY

 TUNNEL SPILLWAY

 SHAFT SPILLWAY

 SIPHON SPILLWAY

 CONCLUSION

 REFERENCES
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LIST OF FIGURES

Fig.NO. Title of figure Page no

1 Straight drop spillway 11
2 Straight drop spillway 11
3 Over flow spillway 12
4 Over flow spillway 12
5 Side channel spillway 13
6 Side channel spillway 13
7 Open channel spillway 14
8 Open channel spillway 14
9 Tunnel spillway 15
10 Tunnel spillway 15
11 Shaft spillway 16
12 Shaft spillway 16
13 Siphon spillway 17
14 Siphon spillway 17
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ABSTRACT

 A spillway is an essential hydraulic structure used to safely

release excess water from a dam or reservoir, ensuring the
prevention of overtopping and potential structural failure.

 It plays a critical role in maintaining the stability of the dam

and managing water levels during normal and flood
conditions.

 Spillways are designed to dissipate the energy of flowing

water to minimize downstream erosion and environmental
damage.

 There are various types of spillways, including overflow

spillways, where water flows over a curved crest; chute
spillways, which guide water down a steep channel; side-
channel spillways, which divert water laterally before
discharge; and shaft spillways, where water flows into a
vertical or sloping shaft. Controlled spillways are equipped
with gates to regulate flow.

 Each type is suited to specific site and operational conditions,

making spillways vital components for dam safety, flood
control, and effective water resource management.

 Spillways are fundamental for flood control, hydropower

operations, and water resource management. Their design and
construction require careful consideration of hydrological,
geological, and environmental factors to ensure safety,
efficiency, and durability over the structure’s lifespan.
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GENERAL INTRODUCTION

A spillway is a critical component of dams and water

management structures, designed to safely convey excess
water from a reservoir to a downstream area. It acts as a
safety valve, preventing overtopping of the dam, which could
lead to structural failure and catastrophic flooding. Spillways
are engineered to handle extreme flows, such as those caused
by heavy rainfall, snowmelt, or other hydrological events.
 Key Functions of Spillways

1. Flood Control: Regulates water levels during floods by

discharging surplus water.

2. Safety: Protects the dam from overtopping, ensuring the

structure's integrity.

3. Erosion Prevention: Directs water flow in a controlled

manner to minimize downstream erosion.

 Key Design Considerations

Hydrology: Understanding maximum potential inflows to

design for peak discharges.

Hydraulics: Ensuring smooth and efficient water flow

without structural damage.

Energy Dissipation: Preventing erosion or damage

downstream using structures like stilling basins or energy
dissipators.

Structural Integrity: Ensuring spillways can withstand high

pressures and flow rates.
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TYPES OF SPILLWAYS

Spillways are structures built to release surplus water from dams or

reservoirs safely. They prevent overtopping and potential dam
failure. Different types of spillways are designed based on site
conditions, discharge requirements, and purpose:

1.straight drop: Straight drop spillways are vertical drop structures

used to release excess water from reservoirs. Water falls freely into
a downstream basin or pool, where energy is dissipated. They are
simple, cost-effective, but require careful erosion control and
energy dissipation measures.

2.Over flow: Commonly used in concrete dams, it has a curved

profile resembling an ogee arch, offering efficient flow control and
energy dissipation.

3. Open channel: This involves a steep sloping channel that

conveys water to the downstream area, suitable for dams in narrow
valleys.

4. Side Channel Spillway: The water enters a channel running

parallel to the dam axis before being diverted downstream, ideal
for sites with limited space.
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5. Shaft Spillway: Known as a "morning glory" spillway, it features

a vertical or funnel-shaped shaft leading water downward, used in
deep reservoirs.

6. Siphon Spillway: Operates on the siphon principle,

automatically starting and stopping flow, commonly used for small
dams.

7.Tunnel spillway: Tunnel spillways are underground channels

designed to divert excess water from reservoirs. Water enters
through an intake structure and flows through a tunnel to a
downstream outlet. Ideal for narrow valleys or mountainous
terrain, they minimize surface disturbance but require precise
engineering to handle high velocities and prevent erosion.

Each type ensures efficient water management while protecting the

structure and surrounding environment.
NECESSITY:
Spillways are vital for ensuring the safety and functionality of
dams and reservoirs. They allow controlled release of excess water
during floods, preventing overtopping that could lead to dam
failure. Spillways regulate reservoir levels, protect downstream
areas from flooding, and dissipate water energy to minimize
erosion. By safeguarding structural integrity and reducing risks to
communities and infrastructure, spillways are indispensable for
flood control, water management, and the long-term reliability of
dams.
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STRAIGHT DROP SPILLWAYS

Straight drop spillways, also known as free overfall spillways, are

hydraulic structures used to safely release excess water from
reservoirs or dams to downstream channels. They are characterized
by a vertical or near-vertical drop from the crest, allowing water to
flow freely over the edge. This design is simple, cost-effective, and
suitable for small to medium-sized dams with moderate flow
requirements.

The falling water dissipates energy upon impact, typically through

a stilling basin or an energy-dissipating pool at the base,
preventing downstream erosion. Straight drop spillways are ideal
for locations with solid rock foundations that can withstand high
impact forces. However, they are less effective for managing large
flood flows compared to other spillway types, such as ogee or chute
spillways.

Despite their limitations, straight drop spillways are widely used

for low-head dams, irrigation projects, and small reservoirs due to
their straightforward construction and low maintenance needs.
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OVERFLOW SPILLWAYS

Overflow spillways are critical hydraulic structures designed to

safely discharge excess water from a dam or reservoir during
periods of high inflow, preventing overtopping and potential dam
failure. These spillways are typically constructed with a smooth,
curved profile to allow water to flow efficiently over the crest and
downstream. The ogee-shaped design is common, as it enhances
flow efficiency by aligning with the natural trajectory of water.

Overflow spillways are often equipped with energy dissipation

features, such as stilling basins, to reduce the high velocity of water
and prevent downstream erosion. They are well-suited for dams
where high volumes of water need to be discharged quickly.

While effective, their performance depends on precise design and

construction, ensuring structural stability and capacity to handle
peak flows. Overflow spillways are commonly used in large dams
and are vital for managing flood events while protecting
downstream areas and the dam itself.
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SIDE CHANNEL SPILLWAYS

A side channel spillway is a type of hydraulic structure used in

dams to safely convey excess water during floods. Unlike
traditional spillways, which direct water straight downstream, side
channel spillways guide water laterally into an adjacent channel
parallel to the dam. This design is particularly useful in areas with
constrained space or where downstream flow alignment is
challenging.

Water flows over the crest of the spillway and into the side
channel, which then directs it to an outlet. These spillways are
often accompanied by a chute or conduit to carry water to a safe
discharge point.

Their efficiency depends on proper design, including the slope,

channel dimensions, and energy dissipation measures to prevent
erosion. Side channel spillways are commonly employed in gravity
dams or arch dams and are ideal for regions with variable flood
conditions, combining safety with adaptability in hydraulic
engineering.
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OPEN CHALLEN SPILLWAYS

An open channel spillway is a widely used structure in dams to

safely pass excess water during floods while minimizing potential
damage. This type of spillway is characterized by its open, free-
flowing design, allowing water to flow directly from the reservoir to
a downstream area, following a controlled path. Typically, open
channel spillways consist of three main components: an overflow
crest, a discharge chute or channel, and an energy dissipation
structure at the outlet.

The overflow crest allows water to spill over during high reservoir
levels. The discharge chute, often constructed with a smooth
surface, guides the water downstream at high velocities. At the
end, energy dissipators like stilling basins or baffles reduce flow
velocity, preventing downstream erosion.

Open channel spillways are simple, cost-effective, and suitable for

large dams. Their efficiency depends on proper design to ensure
adequate capacity, structural stability, and erosion control. They
are crucial for dam safety during flood events.
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TUNNEL SPILLWAYS

Tunnel spillways are hydraulic structures designed to safely convey

excess water from reservoirs or dams during periods of high inflow.
Unlike surface spillways, tunnel spillways use an underground or
partially submerged tunnel to divert water, making them ideal for
locations where space is limited or topographic conditions make
other spillways impractical.

The tunnel typically starts with an inlet structure, which may

include gates or trash racks to regulate and protect the flow. Water
enters the tunnel, which is often designed with a circular,
rectangular, or horseshoe-shaped cross-section to optimize
hydraulic efficiency and structural stability.

Tunnel spillways are commonly lined with reinforced concrete or

steel to withstand high flow velocities and pressures. They are used
in high-head dams or steep terrains and are advantageous for
minimizing surface disruption. Proper design ensures stability,
prevents cavitation, and reduces erosion, making them critical for
dam safety and flood management.
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SHAFT SPILLWAYS

A shaft spillway, also known as a "morning glory spillway," is a

type of hydraulic structure designed to safely control water
overflow in dams and reservoirs. It consists of a vertical, funnel-
shaped shaft that transitions into a horizontal or sloped conduit,
directing excess water downstream. This design is particularly
effective in areas with steep terrain or limited space, as it minimizes
the structural footprint compared to conventional spillways.

Shaft spillways operate based on gravity flow, where water enters

the shaft when reservoir levels exceed the crest height. They are
highly efficient for handling large volumes of water, making them
suitable for flood control.

The shape of the inlet, often circular or elliptical, ensures smooth

flow and reduces turbulence. Proper design and maintenance are
crucial to prevent issues like vortex formation or debris clogging.
Examples include spillways at Monticello Dam in California and
Kariba Dam in Africa.
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SIPHON SPILLWAYS
A siphon spillway is a hydraulic structure used to manage excess
water in reservoirs and dams. It operates on the principle of
siphoning, where water flows through a closed conduit, initially
requiring priming to start the flow. Once operational, the siphon
action enables the spillway to discharge water at high efficiency,
even at relatively low head levels.

Siphon spillways consist of an inlet, an airtight siphon pipe, and an

outlet. When water levels rise above the inlet crest, the pipe fills
and creates a pressure difference that drives the siphon effect.
These spillways are advantageous for their self-regulating
mechanism, compact design, and ability to handle fluctuating flow
rates without moving parts.

However, they require careful design to prevent air leakage and

ensure consistent operation. Siphon spillways are commonly used
in medium-sized dams where simplicity and cost-effectiveness are
priorities, such as irrigation systems and flood control projects.
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CONCLUSION

Spillways are essential components of dam and reservoir systems,

designed to safely discharge excess water and prevent overtopping,
which could lead to catastrophic failures.

Their primary function is to control water levels during periods of

heavy rainfall or snowmelt, ensuring the safety of the structure and
surrounding areas. Various types of spillways, such as chute, shaft,
siphon, and side-channel spillways, are employed depending on
site-specific factors like topography, hydrology, and reservoir
capacity.

Efficient design and maintenance of spillways are crucial to their

reliability. Properly functioning spillways prevent erosion,
structural damage, and environmental harm. They also contribute
to effective flood management and water conservation by
channelling excess flow in a controlled manner.

As climate change increases the frequency of extreme weather

events, the role of spillways in ensuring the resilience and safety of
water infrastructure becomes even more critical, highlighting their
importance in sustainable water resource