Combination of Breakwaters and Groins for Preventing Shoreline Erosion at Senggarang Coast - Diponegoro University | Institutional Repository (UNDIP-IR)
International Conference on Sustainable Development for Water and Wastewater Treatment
Yograkarta, INDONESIA, December I 4- I 5, 2009
Combination of Breakwaters and Groins for Preventirig Shoreline
Erosion at Senggarang Coast, Batu Pahat, Johor, Malaysia
Dwi Tjahjanto
Dr., Faculty of Ciuil and Enviranmental Engineering, Universiti Tun Hussein Onn Malaysia
Email
:
dwi
@ uthm.edu.my
Sri-vana
Dr., Faculty of Engineering, Universitas Diponegoro Indonesia
Email: sri bibeh@Jrahoo.com
Abstract
Greater portion of fourteen kilometres of coastal area of Senggarang area is expected to be
flooded by sea water due to constant.ard gradual erosio,t process which will eventually
eats up the land. If this anticipated event happens, it will render thousands of people livirtg
in that area homeless, and also lose their land for agricultural purposes which is the major
source of their livelihood. A study on the area of erosion has been carried out for
identifying the problem, collecting the data and finding the solution to prevent erosion in
the years to come. It was found that the main reason of occurring erosion due to the soil
that forms the coast is soft which cannot stand to the wave attack even though mangroves
are there. An analysis based on CDAS (GENESIS) has been done as well which yields best
placement and selection of beach structures to anticipate the current and future erosion
where a combination of two beach strr.tctures (breakwaters and groins) b selected to be
implementeri in the area of erosion. Croins are placed at tvvo sides of every estuaries which
steak out into the sea as long as i50 m, while each unit of breakwater is provided 300 n
length and placed perallel with the existing shoreline and 150 m atvay from the shoreline
with gab of 100 n each cther.
1.
INTRODUCTTON
National Coastal Erosion Study of Malaysia fiom November 1984 to January 1986 concluded that
about 29o/o of 4,809 km of llalaysian cciastline are facing critical erosion. It has received amounts of
attention because the coastal erosion impinges directly on many aspects of iife such as industry,
transportation, residential and recreational. Related with Malaysian coastline that is facing critical
erosion, sub district of Senggarang, Batu Pahat, Johor, Malaysia could be disappeared from the earth
soon. About 30;000 residents which stay in 20 villages along the coastal area between Rengit and
Sernerah will lose their land and houses as it will be flooded by the sea water due to gradual coastal
erosion process. Some areas such as Parit Botak, Pantai Sungai Punggor, Kampung Sri Pantai,
Kampung Sungai Lurus, Kampung Parit Balak, Teluk Wawasan and Parit Simin are specifi.ed to have
been facing serious problem since many years ago. Larger portion of the coastal area is expected to be
flooded by sea water due to constant and gradual erosion process which eventually eats up,,the land.
Combination of Breakwaters and Groins far Preventing Shoreline Erosion at Senggarang Coast, Batu Pahat,
Johor, Malaysia
Thousands of people that make use of the wealth of the coastal area for fulfilling their daily needs and
livelihood will lose benefit for millions of Dollar
This phenomenon has drawn the attention of the nearest university (Universiti Tun Hussein Onn
Malaysia) to take away the problem into a research study with a proposal to conduct a research
concerning the coastal erosion problem, its impacts, as well as providing a solution to solve the
existing problems "shoreline erosion and overflow of sea water" in the years to come, with the hope
that the results of the study could be adopted as a scientific document for supporting the Govemment
decision makers.
2.
LOCATION AND CONDITION OF A,REA OF STI.TDY
The area of study is located in Senggarang costal area (shoreline) of Batu Pahat, Johor State,
Malaysia. This lies between the coordinates of (108" 53' 30" to l08o 59' 30" Ea3t Longitude and 07o
22' 3A" -A7'37'00" South Latitude). Figure I shows the location of the area of study at Senggarang
that is between Pulau Tikus and Punggur Beach.
Fig. 1: Map showing research location
t-
International Conference on Sustainable Development for Water and Wastewater Treatment
it is known that the dominant wave
From the site visit, problem identification and data collection,
from 1.5 m to 2.5 m, while tide is
direction is from south west. The occurred wave always increases
varied and has tendency increabing. This phenomenon may be caused by the global warming has
influenced thc i..,eaiher that is able'to change the condition of sea water to make the height of wave
and tide is higher than the previous one.
of sea water condition is proved by the-existing beach skucture (breakwater). has been over
nowiby sea water, so ihen the structure cannot break the wave or not function optimally to make the
shoreline has tendency to move to the land. Based on the map survey, information from the
sunounding people and spot observation, it is concluded that within around 40 years the shoreline has
moved to the land until200 m to 300 m away or averaging about 5 m to 7.5 m a year.
Change
in the Senggarang coast is a process of shoreline moving to the land which is caused
by: a) the tendency of increasing of sea water level which can be seel by overtopping on the existing
bieakwater structure; b) the material that forms the coast is soft soil where this kind material is not
rble to detain force of wave even though mangrove trees are available to protect the beach; c) the
amount of formed sediment hansport is not balance where inflow of sediment is less than outflow; and
d) the equiiibrium in the coastal is disturbed by the existing structure that sticks out into the sea, for
example in Punggur beach there are two jeiiies r:earby the drain where the direction of wave is from
south west, then at left siCe ofjetty got accretion while at the right side ofjetty got erosion.
Seashore erosion
3.
ANALYSIS OF WAVE
One of most important data for system analysis of a coastal area is wave where wind and fetch data
will cause the wave of sea to occur. Hence data of wind is required to calculate or forecast the height
and direction of wave at the area of study. Wave forecasting is depending on the wind data as the
principal wave generator and also the fetch. The wind data with the direction used is from the year
1999 to 2009 for Batu Pahat Senggarang data, while the fetch area for Senggarang is refened to
Sumatra Island, In
Yograkarta, INDONESIA, December I 4- I 5, 2009
Combination of Breakwaters and Groins for Preventirig Shoreline
Erosion at Senggarang Coast, Batu Pahat, Johor, Malaysia
Dwi Tjahjanto
Dr., Faculty of Ciuil and Enviranmental Engineering, Universiti Tun Hussein Onn Malaysia
:
dwi
@ uthm.edu.my
Sri-vana
Dr., Faculty of Engineering, Universitas Diponegoro Indonesia
Email: sri bibeh@Jrahoo.com
Abstract
Greater portion of fourteen kilometres of coastal area of Senggarang area is expected to be
flooded by sea water due to constant.ard gradual erosio,t process which will eventually
eats up the land. If this anticipated event happens, it will render thousands of people livirtg
in that area homeless, and also lose their land for agricultural purposes which is the major
source of their livelihood. A study on the area of erosion has been carried out for
identifying the problem, collecting the data and finding the solution to prevent erosion in
the years to come. It was found that the main reason of occurring erosion due to the soil
that forms the coast is soft which cannot stand to the wave attack even though mangroves
are there. An analysis based on CDAS (GENESIS) has been done as well which yields best
placement and selection of beach structures to anticipate the current and future erosion
where a combination of two beach strr.tctures (breakwaters and groins) b selected to be
implementeri in the area of erosion. Croins are placed at tvvo sides of every estuaries which
steak out into the sea as long as i50 m, while each unit of breakwater is provided 300 n
length and placed perallel with the existing shoreline and 150 m atvay from the shoreline
with gab of 100 n each cther.
1.
INTRODUCTTON
National Coastal Erosion Study of Malaysia fiom November 1984 to January 1986 concluded that
about 29o/o of 4,809 km of llalaysian cciastline are facing critical erosion. It has received amounts of
attention because the coastal erosion impinges directly on many aspects of iife such as industry,
transportation, residential and recreational. Related with Malaysian coastline that is facing critical
erosion, sub district of Senggarang, Batu Pahat, Johor, Malaysia could be disappeared from the earth
soon. About 30;000 residents which stay in 20 villages along the coastal area between Rengit and
Sernerah will lose their land and houses as it will be flooded by the sea water due to gradual coastal
erosion process. Some areas such as Parit Botak, Pantai Sungai Punggor, Kampung Sri Pantai,
Kampung Sungai Lurus, Kampung Parit Balak, Teluk Wawasan and Parit Simin are specifi.ed to have
been facing serious problem since many years ago. Larger portion of the coastal area is expected to be
flooded by sea water due to constant and gradual erosion process which eventually eats up,,the land.
Combination of Breakwaters and Groins far Preventing Shoreline Erosion at Senggarang Coast, Batu Pahat,
Johor, Malaysia
Thousands of people that make use of the wealth of the coastal area for fulfilling their daily needs and
livelihood will lose benefit for millions of Dollar
This phenomenon has drawn the attention of the nearest university (Universiti Tun Hussein Onn
Malaysia) to take away the problem into a research study with a proposal to conduct a research
concerning the coastal erosion problem, its impacts, as well as providing a solution to solve the
existing problems "shoreline erosion and overflow of sea water" in the years to come, with the hope
that the results of the study could be adopted as a scientific document for supporting the Govemment
decision makers.
2.
LOCATION AND CONDITION OF A,REA OF STI.TDY
The area of study is located in Senggarang costal area (shoreline) of Batu Pahat, Johor State,
Malaysia. This lies between the coordinates of (108" 53' 30" to l08o 59' 30" Ea3t Longitude and 07o
22' 3A" -A7'37'00" South Latitude). Figure I shows the location of the area of study at Senggarang
that is between Pulau Tikus and Punggur Beach.
Fig. 1: Map showing research location
t-
International Conference on Sustainable Development for Water and Wastewater Treatment
it is known that the dominant wave
From the site visit, problem identification and data collection,
from 1.5 m to 2.5 m, while tide is
direction is from south west. The occurred wave always increases
varied and has tendency increabing. This phenomenon may be caused by the global warming has
influenced thc i..,eaiher that is able'to change the condition of sea water to make the height of wave
and tide is higher than the previous one.
of sea water condition is proved by the-existing beach skucture (breakwater). has been over
nowiby sea water, so ihen the structure cannot break the wave or not function optimally to make the
shoreline has tendency to move to the land. Based on the map survey, information from the
sunounding people and spot observation, it is concluded that within around 40 years the shoreline has
moved to the land until200 m to 300 m away or averaging about 5 m to 7.5 m a year.
Change
in the Senggarang coast is a process of shoreline moving to the land which is caused
by: a) the tendency of increasing of sea water level which can be seel by overtopping on the existing
bieakwater structure; b) the material that forms the coast is soft soil where this kind material is not
rble to detain force of wave even though mangrove trees are available to protect the beach; c) the
amount of formed sediment hansport is not balance where inflow of sediment is less than outflow; and
d) the equiiibrium in the coastal is disturbed by the existing structure that sticks out into the sea, for
example in Punggur beach there are two jeiiies r:earby the drain where the direction of wave is from
south west, then at left siCe ofjetty got accretion while at the right side ofjetty got erosion.
Seashore erosion
3.
ANALYSIS OF WAVE
One of most important data for system analysis of a coastal area is wave where wind and fetch data
will cause the wave of sea to occur. Hence data of wind is required to calculate or forecast the height
and direction of wave at the area of study. Wave forecasting is depending on the wind data as the
principal wave generator and also the fetch. The wind data with the direction used is from the year
1999 to 2009 for Batu Pahat Senggarang data, while the fetch area for Senggarang is refened to
Sumatra Island, In