Coastal Assignment

7/27/2019 Coastal Assignment

1/14

TABLE OF CONTENT

INTRODUCTION ....................................................................................................................................... 2

BACKGROUND ......................................................................................................................................... 4

PROBLEM STATEMENT ............................................................................................................................ 6

METHOD .................................................................................................................................................. 8

CONCLUSION ......................................................................................................................................... 14


2/14

Page | 2

INTRODUCTION

Coastal engineering is one of the parts in civil engineering. Coastal engineering is study

the processes happen at shoreline and construction within coastal zone. The coastal zone areais from interaction between sea and land processes occur or more specific air-sea-land

interface zone around continents and islands (Firn Crichton Roberts Ltd and University of

Strathclyde 2000). The process involves is tides, wave, and other that may cause changes

structure of the land.

The field involves aspects of near shore oceanography, marine geology, and civil

engineering, the erosion of coast and providing navigational access. Coastal engineering are

very important at Malaysia because most of Malaysia land is surrounding by coast. In

Malaysia, we have west coast, east coast, Sabah coast and Sarawak coast. The importance of

coast is to defend it from tsunami, flooding or breaker for the big wave. Most of the coast in

Malaysia consist muddy coast and sandy coast.

Green coast is preserving the coast before destroyed cause by construction,

deforestation of mangrove tree and conserve it. It is because the development of construction

may affect the coastal habitats and societies of the coastal area. The way to develop green

coast is by maintain and restore their natural ecological system by planting back the

mangrove forest because mangroves are complex ecosystems that provide coastal bioshield to

save guard coastal habitats and societies from natural disasters.

Thus, green coast is very important because it can conserve and preserve the coast from

destroyed by any factor such as flooding, tsunami, strong wave surges and other. From our

understanding, green coast is an activity to preserve, conserve and maintain the richness of

biodiversity element such as mangrove forest, flora and fauna, also fish and animal habitat.

This unique habitat and environment are so important because they have benefit to our

ecosystem.

Drainage and Irrigation Department (DID) and Environment Department is one of the

authority selected by malaysia government that working on issue conservation, preserve and

make research about the coastal area. The main target of green coast is to maintain the

ecosystem of coastal region and prevent it from having a pollution problem, erosion and

extinction of mangrove forest. The green coast issue started when too many development of

construction at coastal and hard engineering occur.


3/14

Page | 3

Furthermore, the demolished of flora and fauna at coastal area are the most importance

issue to overcome to avoid extinction of flora and fauna that may affect ecosystem of coastal

area. Thus, we have choosen Pantai Sg. Haji Dorani as study area because it provides the

opportunity to mitigate erosion as well as improve ecological and socio-economic aspects of

coastal areas, both of which are of great importance to local communities and authorities.


4/14

Page | 4

BACKGROUND

Sg. Hj. Dorani is located 90 km to the north of Kuala Lumpur, near Sabak Bernam, on

the west coast of Peninsular Malaysia (Fig. 1). It is nearly 2.6 km long and has a 1:100foreshore slope. Bernam River and Perak River both carry huge amount of sediments to the

Malacca Strait (Cleary and Goh, 2000), meet the coastline some 40 km away from Sg. Hj.

Dorani. Littoral currents distribute this fluvial discharge over the shoreline to the Sg Hj

Dorani beach where destruction of the coastal forest decreases the chance of sediment

deposition. Therefore, it was anticipated that mangrove replanting in this area could help with

trapping the sediment. Recently, the muddy beach of Sg. Hj. Dorani has become subject to

engineering and ecological projects on account of the beach critical situation caused by

human induced alterations. In 1977, to protect the coastal area against tidal inundation a dyke

was constructed along the shoreline by DID. The dyke faced severe erosion during the 1980s.

Hence, in 1991, during maintenance, a length of 1.5 km of the seaward slope of the dyke was

covered with concrete armour units along the Northern and the Central beaches where the

dyke was exposed to the wave action. In order to protect the concrete armour layer from the

toe scour, a 5-m-wide rock mat was constructed in front of the toe along the Central beach.

Today, the dyke has a crest elevation of 3.20 m above MSL (mean sea level), and thetoe elevation is averaged at about 0.75 m MSL. Although the embankment has strongly

prevented the shoreline from retreating and protected the agricultural land against flooding,

its construction process accelerated mangrove degradation. Moreover, this barrier broke the

link between the mangrove and backshore and prevents mangroves from migrating landward.

Consequently, the mangrove area has been sandwiched between the dyke from the landward

side, and the wave action from the seaward side. In 2006, DMuara Marine Parks

construction activity along the Southern beach destructed the existing mangrove forest in the

recreational area. Currently, the mangrove forest is limited to an area between Southern and

Central beaches that only covers 800 m of the Sg. Hj. Dorani beach.

The Sg. Hj. Dorani beach is predominantly covered by mud deposits. Based on a

hydrometer analysis with samples taken from the restoration area at depths of 5100 cm, the

mud contains a mixture of 22% clay (


5/14

Page | 5

from May to September and the Northeast monsoon from November to March.The period of

change between the two monsoons is a transitional period which occurs in April and October.

Heavy rainfall often occurs during these two transitional periods (Desa et al., 2001; Suhaila

and Jemain, 2007). Tropical climate is experienced year-round with an average annual

precipitation of 1790mm. The relative humidity ranges from 80 to 90% and the temperature

averages from 22 to 33 C throughout the year. The waves are generally wind-generated

waves. The most frequent waves are those from the SW (during the southwest monsoon) and

WNW (during the northeast monsoon). The strongest winds occur during the northeast

monsoon from WNW with a speed between 10 and 20 knots; winds from the SW, on the

other hand, seldom exceed 15 knots. The significant wave height is lower than 1 m around

89% of the time. The significant offshore wave height with a return period of 10 years is 1.50

m. The tidal regime is semi-diurnal with a maximum tidal range of 3.2 m.

Fig. 1. Study area on the west coast of Peninsular Malaysia.


6/14

Page | 6

PROBLEM STATEMENT

Since Sg Hj Dorani is an exposed beach, many young plants are often knocked down and

washed away by storm waves and surges.

Wildings ofAvicennia scouring and slowly disappeared

Coastal erosion is the wearing away of land and the removal

ofbeach ordune sedimentsby wave action, tidal currents, wave currents or drainage. Waves,

generated by storms, wind, or fast moving motor craft, cause coastal erosion, which may take

the form of long-term losses of sediment and rocks, or merely the temporary redistribution of

coastal sediments. This is strengthened by reality that this coast was located at Malacca

Straits which are the busiest trade route for ships. This will make the coast become shorter in

length due to this phenomenon.

Example of coastal erosion
http://en.wikipedia.org/wiki/Beachhttp://en.wikipedia.org/wiki/Dunehttp://en.wikipedia.org/wiki/Sedimenthttp://en.wikipedia.org/wiki/Wavehttp://en.wikipedia.org/wiki/Tidehttp://en.wikipedia.org/wiki/Erosionhttp://en.wikipedia.org/wiki/Rock_(geology)http://en.wikipedia.org/wiki/Rock_(geology)http://en.wikipedia.org/wiki/Erosionhttp://en.wikipedia.org/wiki/Tidehttp://en.wikipedia.org/wiki/Wavehttp://en.wikipedia.org/wiki/Sedimenthttp://en.wikipedia.org/wiki/Dunehttp://en.wikipedia.org/wiki/Beach


7/14

Page | 7

Due to the strong waves that generated from winds and the ships travelled, the existing

mangroves was washed away or knocked down. If no action is taken, the coast will erode and

become shorter, hence will sink the existing land and at the worst, it will affect the structures

that build along the coast. This will endangered human safety.


8/14

Page | 8

METHOD

Coastal Rehabilitation

Coastal rehabilitation is one of the way towards the green coast. Historically, the coastlines of

Malacca Strait have been protected by mangroves, and therefore restoration of these valuable

forests is the best option for stabilising the shorelines. It is almost impossible to bring back

the pristine condition, but mangrove restoration could still improve the natural protective

system because mangroves can mitigate the wave effect on shorelines and simultaneously

trap and stabilise sediments (CEM, 2006). In addition, mangrove replanting enhances the

ecology and socio-economic aspects of the coastal zone (Valiela et al., 2001; Gilman et al.,

2008; Nagelkerken et al., 2008;Walters et al., 2008). To ensure that the rehabilitation effort

will be able to assist the natural recovery, an area in the Central beach adjacent to the

northwest boundary of the existing mangrove site was selected as the study site by DID.

Mangrove restoration in this area was anticipated to enhance the existing mangroves in the

neighbouring site by extending the margins of mangroves and augmenting the accretion of

sediments on the beach. Also, easy access to the site makes it convenient for construction,

restoration, and monitoring.

Fig. 2. Plan view of the multi-structure and the project site


9/14

Page | 9

Detached breakwater, design and construction. Lowwave-energyclimate which is suitable for

mangrove to establish its roots in the substrate (CEM, 2006) could be provided by a coastal

protective structure (Gilman and Ellison, 2007). For this purpose, a detached multiple

structure was considered as the most suitable option for this area. From the environmental

viewpoint, low crested structures are more acceptable on account of visual aspects and water

quality (Zanuttigh et al., 2005). Moreover, low crested structures produce lower catastrophic

environmental impacts (Burcharth and Lamberti, 2004) and minimized morphological side

effects in comparison with emerged (traditional) structures.

Crest elevation assessment is among the most important parameters in breakwater design

which has a significant effect on both hydraulic stability of the structure and the breakwaters

function (Dean et al., 1997). A higher crest elevation results in a lower wave transmission,but it increases the amount of required materials (the construction costs). Moreover, smaller

armour stones can be used on the seaward slope of a low crested structure (compared to

emerged structures) as wave energy can partly pass over the crest (Van der Meer and

Pilarczyk, 1990).


10/14

Page | 10

Geotextile tubes

Geotextile tubes of diameters of up to 3m, made up of woven or knitted high strength fabric

have been effectively used to control both inland and oceanfront erosion. Length of geotubes

is decided based on ease in handling/placing and sand filling.The main tubes are generally

flanked by tubes of smaller diameters on upstream side which help in resisting lateral

pressure. Also, it is required to provide cover to geotubes to protect them from

degradation/damage.

Figure 3. Multiple geotubes stack arrangement for erosion control ( Koerner, 2000).

JPS Malaysia has been working on to construct geotubes along the coast but because of

heavy waves occurred, leakages can be easily occured. So JPS has suggested some ways to

repair the condition of geotube in Sg. Haji Dorani coast is by :-

a) Geotube that has leaked lined with a layer of geotextile


11/14

Page | 11

b) On top of this layer of geotextile in place crushed stone as a coating followed by alayer of aggregate grade B (average size 290 mm).

c) Reclaimed aggregates up to a peak ("crest level") to the next geotube.d) A layer breakwater "SAUH" made of concrete aggregates arranged on earlier.

The construction cost of geotube damaged stretch (about 18 meters long) in October 2011 is

estimated at RM60, 000.Geotubes provide the excellent solution for beach erosioncontrol.

However, it needs to be protected from damagedue to wave action and ultraviolet light by

providingriprap. Also, tidal variation and wave height need to beconsidered in design of

geotubes.

Figure 4. Geotubes design implement in Sg. Haji Dorani coast.


12/14

Page | 12

Fig. 5. Sketch map of the positions of wildings, planted wild saplings and seeds at

therestoration area.

Breakwater structure 'Geotube 1' has

been leaked over 2 meters.

Pictures around the structure Geotube to

L Block (distance 530 m long)

o Breakwater construction cost estimate around RM 1 MILLION for 500 m long.


13/14

Page | 13

P

Figure 6. Planting at Sg. Haji Dorani

Comp-Mat

Comp-Pillow


14/14

Page | 14

CONCLUSION

As the conclusion, the success of green coast project at Sungai Haji Dorani will affect the

ecosystem of coastal area at the area. The green coast activity such as mangrove restorationand others will make Sungai Haji Dorani as a tourism places and bring the cultural habitat

back to its normal. Its because the function of mangrove forest as we know can be a

waterbreaker.

Furthermore, coastal area at Sungai Haji Dorani has been suffered by erosion of sand. It is

probably can cause the surrounding area of Sungai Haji Dorani be destroyed. House and

other tourism place will be demolished by the wave. Thus, the movement of wave will lead to

surface changes of Haji Dorani coastal area. So, green coast can prevent the changes of

structure at Sungai Haji Dorani.

Green coast at Sungai Haji Dorani is so importance because we can make Sungai Haji Dorani

as tourism place. The green coastal at Sungai Haji Dorani will attract the animal, insect and

others to live and breeding at their natural habitat. The mangrove restoration will attract fish

and aquatic animal to breeding at mangrove forest and it will become give benefit to tourist

because they can look the natural habitat of animal at Sungai Haji Dorani. The local

authorities have taken part to promote Sungai Haji Dorani when we can apply green coast at

Sungai Haji Dorani area.

Documents

Coastal Assignment