This is based on a model for coastel wave defence system. It has various propoaed structures which can mitigate the problems arising from rise in sea water level ro protect coastal areas

1. MODEL STUDY ON
COASTAL WAVE DEFENCE
SYSTEM
Presented By -
Vaibhav Khodake

2. INTRODUCTION
 The coast, also known as the coastline is the area where land meets the sea
or ocean, or a line that forms the boundary between the land and the ocean
or a lake.
 Coastal zones occupy less than 15% of the Earth's land area, while they host
more than 45% of the world population. Coastal management is defense
against Coastal Overflow & Erosion.
 This project helps to show how different coastal structures, such as offshore
breakwaters, seawall and sloping beaches, interact with coastal processes and
influence rates of Erosion & Overtopping to some extent.
 This large coastal protection structures can be build using different types of
construction material such as rubble mound, granite masonry or reinforced
concrete.

3. PROBLEM STATEMENT
 The reason for coastal management is obvious ,to protect coastal structures
from being damaged and even destroyed by coastal erosion or overflowing.
 Failure to do so can have severe economic and social effect ,especially along
coastline which are used for tourism and industry.
 Management of coastlines is also important to help protect natural habitats,
however governments generally don’t engage in coastal management where
there is an economic risk as effective coastal management is very expensive.

4. OBJECTIVES
 Model study on different energy dissipating structures to prevent Erosion and
Coastal Overflowing.
 To prepare a model of coastal area to study energy dissipation of coastal
waves.
 To study Dimensional Analysis of the respective model.
 To develop effective energy dissipating structure to reduce erosion.

5. SCOPE OF PROJECT
 This project helps to show how different coastal structures, such as an
offshore breakwater, sea defenses and sloping beaches, interact with coastal
processes and influence rate of erosion and overflowing.
 Coastal structures are used in coastal defense schemes with the objective of
managing shoreline erosion and preventing overflowing of water.
 It’s becoming increasingly important for councils and governments to start
managing coastlines in order to protect them from increasing coastal erosion
and overflowing due to altering sea levels.
 To move people out of danger zone.
 New defence can be built further out in the sea in an attempt to reduce the
stress on current defences and possibly extend the coastline slightly.

6. CHALLENGES IN THE PROJECT
 Constructing a structure which can sustain different weather conditions
and sea levels.
 To understand wave conditions in different places.
 To know the effect of waves on coastline.
 Practical execution of proposed structures.

7. LITERATURE REVIEW
Griggs, Gary B., and Tait, James F., 1989, "Observations of the
End Effects of Seawalls" in Shore and Beach, Vol. 57, No. 1, pp
25-26.
Through the monitoring of beach changes over two years in the vicinity of
various types of seawalls, visual observations of the end section of the walls
indicated that when they were under direct wave attack, wave reflection
was occurring. The extent to which this reflection had an impact downcoast
appears to be dependent on wave height and wave period. Other factors which
appear to have an influence on the end effect of seawalls are the angle of
wave approach and the geometry and permeability of the end section. A lowered
beach profile was observed up to 150 meters from the downdrift end of
the seawall. It was also noted that the extension of the structure seaward
was also a factor in determining the amount of scour or erosion.

8. Tank & Wave Dimensions
OBJECT BREADTH (IN
CM)
LENGTH
(IN CM)
DEPTH/HEIGHT QUANTITY
TANK 20 160 1) 60cm(At motor
end)
2)40cm(At fixed wall
end)
-
WAVE 18 120 9cm (from crest to
the bottom of tank)
20 Liters of
saline
water

9. MODEL SPECIFICATIONS
• Scale of model = 1:100
• Velocity of Wave ( 𝑉
𝑚 ) = 1.4 m/s
• Depth of Wave ( 𝐿𝑚 ) = 9 cm = 0.09 m
• Depth of Water = 7.5cm = 0.075 m
• Vol. of Saline Water = 20 litres = 20× 10−3 m3
• Length of Coastline = 18 cm = 0.18 m
• Density of Saline Water = 1023.6 ≅ 1025 kg/m3

10. PROPERTIES OF WAVE
1) Velocity(V) =
𝑊𝑎𝑣𝑒𝑙𝑒𝑛𝑔𝑡ℎ
𝑃𝑒𝑟𝑖𝑜𝑑(𝑇𝑖𝑚𝑒)
V =
𝜆
𝑇
∴ 1.4 =
𝜆
0.7
∴ 𝑊𝑎𝑣𝑒𝑙𝑒𝑛𝑔𝑡ℎ ( 𝜆 ) = 1 m
2) Velocity = Wavelength x Frequency
∴ Frequency =
𝑉𝑒𝑙𝑜𝑐𝑖𝑡𝑦
𝑊𝑎𝑣𝑒𝑙𝑒𝑛𝑔𝑡ℎ
=
1.4
1
= 1.4 Hz
3) Amplitude = 9 cm = 0.09 m

11. Using Froude’s Law,
 (Fr )Prototype = (Fr) Model
∴
𝑽𝑷
𝒈𝑷𝑳𝑷
=
𝑽𝒎
𝒈𝒎𝑳𝒎
 𝑉
𝑚 = 1.4 m/s ; (𝐿𝑚)Wave = 0.09 m
 𝑔𝑃 = 𝑔𝑚 = 9.81 m/s2 ; 𝐿𝑅 = 100 =
𝐿𝑝
𝐿𝑚

𝐿𝑝
0.09
= 100 ∴ 𝐿𝑝 = 9m

12.  ∴ 𝑉𝑃 = 𝑉
𝑚 ×
𝐿𝑝
𝐿𝑚
= 1.4 × 100
∴ 𝑉𝑃 = 14 m/s
Now,
(Fr )Prototype =
𝑉𝑃
𝑔𝑃𝐿𝑃
=
14
9.81×9
= 1.489 ≅ 1.5
(Fr) Model =
𝑉𝑚
𝑔𝑚𝐿𝑚
=
1.4
9.81×0.09
≅ 1.5
∴ (Fr )Prototype = (Fr) Model
∴ By Froude’s Law The Model and Prototype are Dynamically Similar.

13. SR
NO.
Coastal Structure Volume
(In ml.)
Average
Volume
Type of wall Type of structure I II III
1. Fixed wall Submerged Breakwater
A) Distance From i) 50 cm
Fixed wall ii) 60 cm
iii) 70 cm
0 0 0
4 6 7
18 23 20
0
6
20
2. Recurved wall i) Slope 1:2
ii) Slope 1:6
5 5 5
5 5 5
5
5
3. Fixed wall Tetrapods / Rock Armor
A) Position i) Flat
ii) Inclined
5 5 5
0 0 0
5
0
4. Fixed wall Stepped Slope 57 65 73 65
5. Fixed wall i) Slope 1:2
ii) Slope 1:6
198 206 196
138 150 147
200
150
6. Fixed wall N.A 152 155 158 155
OBSERVATIONS

14. SR
NO.
Coastal Structure Volume (In liters.) Volume
(Percentage)
Type of wall Type of structure Case I (50x) Case II (100x)
1. Fixed wall Submerged Breakwater
A) Distance From Case I Case II
Fixed Wall i) 25 m i) 50 m
ii) 30 m ii) 60 m
iii) 35 m iii) 70 m
0 0
0.3 0.6
1 2
0%
0.03%
0.1%
2. Recurved wall i) Slope 1:2
ii) Slope 1:6
0.25 0.5
0.25 0.5
0.025%
0.025%
3. Fixed wall Tetrapods/Rock Armor
A) Position i) Flat
ii) Inclined
0.25 0.5
0 0
0.025%
0%
4. Fixed wall Stepped Slope
5. Fixed wall i) Slope 1:2
ii) Slope 1:6
10 20
7.5 15
1%
0.75%

15. Wave Tank

16. Rock Armour

18. Conclusion
 From the above table we get to know the performance levels of different
structures against the propagation of waves towards them. The table values
above represent the overtopping of waves.
 In the above table, recurved wall, breakwater and rock armour have turned
out to be more effective.
 In case of breakwater it does not allow any overtopping. It is effective in high
tide conditions. But it has its disadvantage, as it is constructed away from the
shoreline in the water and it is not an economical structure. When this
structure is to be chosen the above points need to be considered.
 In case of rock armour it is most effective and economical structure. It is
generally used in every part of the world. Rock armour is a modern reliable
structure that is used for protecting shoreline.

19. THANK
YOU