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CHAPTER 2A7A- EROSION AND COASTLINE CHANGES
2A7.1 Introduction
Beach erosion is a world-wide phenomenon and is especially of concern to areas in which
tourism is heavily dependent on beaches to attract visitors. The causes of erosion are many and
often a multitude of causes are responsible. The impacts can be extremely severe leading to
abandonment of settlements where the coastline cannot be defended. The occurrence and severity
of erosion is expected to increase in future in view of global warming and the resultant rising sea.
The usual response to erosion by locals is to defend the coast by emplacement of anti-erosion
structures. Authorities usually respond by erecting costly, massive structures or employing beach
nourishment. Not all the measures taken have been successful. This may be due to a lack of
understanding on erosion or a lack of baseline information on which to design suitable structures.
Shoreline management is often about managing erosion. To do this effectively, historical data to
predict trends is essential. Unfortunately such data is often lacking and when available is
unreliable because of the method used in measuring change. South Pahang is no exception and it
would be prudent to embark on a monitoring programme to collect the essential baseline data on
various aspects of erosion. There is absolutely no information on the rate of coastline change for
South Pahang in the NCES of 1985. It would be extremely difficult to plan and manage the
shoreline in the absence of this vital information.
There is often less emphasis on erosion than on the impacts of erosion. For example the erosion
classes adopted in the 1985 study is based on socio-economic impacts of erosion. A lack of
understanding of this may result in a misunderstanding of the state of erosion. An increase in
critically eroding areas may be a simple case of an increase in unregulated beach-front
development and has nothing to do with a change in the state of erosion. In fact, an increase in
critically eroding sites may take place even when the extent and rate of erosion is decreasing.
The status of erosion in Southern Pahang in 1985 (EPU 1985) is summarized in Table 7-1. Out of
a total length of 103 km of coastline, 41.7% was in retreat. However, erosion was considered to
have insignificant or no socio-economic impacts and all the retreating coasts were classified as
category III. Erosion was considered acceptable, that is ‘no significant social and economic losses
from erosion are expected within the next 10-15 years. The recommendation was that no action
be taken to address the erosion other than to undertake periodical monitoring. No information was
provided on the rate of shoreline retreat for the whole Southern Pahang coast. The only structure
documented was a gabion wall in poor condition between Kampung Tering and Nenasi – a
coastline length of 8 km. The gabion wall was described as in Pantai Hiburan and had failed (see
Table 7.2 in NCES 1985). The structure was assessed as not suitable for permanent works and
considered not suitable or effective. Since no georeference was given or photographs shown for
the structure, tracking down the failed gabion presented some problems. The coastline length
from Kg. Tering to Nenasi is 8 km long but there is no Pantai Hiburan located along the stretch.
Two beaches are referred to locally as Pantai Hinuran, one just north of Agrobest in Pekan and
the other in Rompin. There are, however, two recreational beaches between Kg. Tering and
Nenasi, a popular one in Tanjung Batu and an obscure one at the mouth of Sg. Tering. No
structures were detected on the ground in both places.
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Table 7-1. Status of erosion in Southern Pahang 1985 (after NCES 1985)
Stretch
Kuala Pahang
K. Pahang - Sg.
Miang
Sg. Miang – Kg.
Tering
Kg. Tering Nenasi
Nenasi - Bebar
Sg. Bebar
Bebar
–
Pengkalan Balai
Pengkalan Balai Kg. Block
Kuala Mercung
K. Mercung –
Leban Condong
Leban Condong –
Tg. Tengku
Kuala Rompin
Kuala RompinKg. Tg. Pahang
Total Length
Total retreat
Total stable
% retreat
% stable
Length
(km)
0.3
17.0
Shoreline
condition
retreat
stable
Category
Structures
Recommendation
III
none
Monitor periodically
18.5
retreat
III
none
Monitor periodically
8.0
retreat
III
4.0
0.1
13.5
retreat
retreat
stable
III
III
Gabion wall,
condition
none
none
1.5
stable
0.1
14.0
retreat
stable
III
None
Monitor periodically
8.5
stable
1.0
16.5
retreat
retreat
III
III
None
None
Monitor periodically
Monitor periodically
poor
Monitor periodically
Monitor periodically
Monitor periodically
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48.5
54.5
41.7
58.3
2A7.2 Erosion
Areas of erosion, usually indicated by the presence of structures, vegetation and morphological
indicators or from accounts by locals, were identified and mapped in the field using DGPS. A
field proforma was administered for badly eroding coasts. Based on the information collected on
socio-economic impact, the coast was classified as category I (critical), category II (significant)
or category III (acceptable), following the definition of these classes in the 1985 National Coastal
Erosion Study. The results are summarized in Table 7-2. Where responses have been made for
formerly critical erosion sites, the status of the coastline is assessed after the emplacement of the
structure. If erosion has been adequately mitigated, then the coastline is taken out of the list of
critical erosion. A case in point is the Tanjung Pahang and Agrobest coast now protected by
revetment. However, where the effectiveness of mitigations employed have yet to be proven then
the original category is retained as in the case of the gabions in Sungai Nibung. Because of the
nature of the definition, unregulated development or development without due consideration of
shoreline dynamics can suddenly turn a previously acceptable eroding coast into one of critical
erosion when the built structures are seriously threatened by erosion, as in Seratus at the southern
bank of Sungai Rompin. Hence, an increasingly percentage of coastlines having critical erosion
may not an indicator of increasing occurrence or rate of erosion but may reflect an increase in
beach front development. Undeveloped coast such as the stretch between De Rhu and Summerset,
irrespective of the severity of erosion, cannot be a critical eroding coast because there is no severe
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socio-economic impact. But once developed, the erosion may become critical. Thus, a better
approach in reducing the length of critical eroding coast may not be reactive but rather a proactive
one in reducing the socio-economic impacts of erosion by permitting development only behind a
designated buffer zone or setback.
Table 7-2. Erosion, impacts and categories of mainland coast, South Pahang
C3S1M1
C3S1M2
C3S1M3
C3S1M4
C3S1M5
C3S1M6
GPS (RMSO)
A. 387800/609250
B. 387100/ 609700
to
384250/ 609720
AREA
‘Stable’
section of
spit
IMPACTS
Landward migrating spit and loss of
casuarinas and mangroves. Sand overwash.
Unpopulated coast
CAT
III
381900/605850 to
380200/605200
North of JPS
canal
III
A. 379300/605200
B. 379300/605000
to
378600/ 604700
A. 367900/ 403500
B. 367550/403500
C. 366700/603648
JPS canal to
new Miang
mouth
Retreating sandy coast and loss of coastal
trees along mainland coast, undeveloped
coast
Retreating coast and loss of coastal trees,
undeveloped coast
I
364349/604026 to
364296/604056
Sg. Nibung
Scarped coast
364228/604507 to
362276/604505
Hiburan
(Pekan)
356951/605523 to
356596/605568
Agrobest
Coastal road threatened in three locations
and recreational facilities lost including a
tarred car park and a shed. Some
realignment of road
Long history of erosion, coastal road
threatened, various attempts in past to
mitigate erosion. Currently a long gabion
wall built to protect the coastline
accompanied by sand dumping. Road
relocation required eventually. Inland road
reserve already set aside. Erosion still a
problem as repeated failures of gabion
Scarped coast, long history of erosion, area
previously occupied but now unoccupied,
popular picnic and camping area. Road
relocation required eventually, inland road
reserve already in place
Aquaculture ponds and land lost, part local
golf course lost, long erosion history,
various attempts made in past to mitigate
erosion, erosion problem initiated or
aggravated by human action. Most recently
revetment and some local nourishment.
Erosion mainly downdrift of structure
constructed to train canal outlet, which acts
as a groyne. Scarped coastline. Unprotected
section Category I
Localized river bank and coastal erosion
Road, school and property threatened,
overwash a problem
A short stretch of scarped coast with fallen
casuarinas
I
Twin Hut
Coast
Scarped coast
356596/605568 to
355546/605773
C3S1M7
A. 353800/405900
B. 352500/405600
C. 349100/405550
346990/605794 to
346797/605816
346000/405800
North
Nenasi
Nenasi
Nenasi spit
III
I
II
Ex I
I
III
III
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C3S2M1
C3S2M2
C3S3M1
C3S3M2
A. 342200/605000
B. 388900/604800
C. 338000/604700
332800/604550 to
329800/604500
324700/604100 to
322115/604686
312100/609300 to
312600/609300
311908/609134 to
311813/608975
311342/610613 to
311344/610689
Kg. Padan
area
Parts of
Mercung
spit
Summerset
North bank
Rompin BR
Tg. Tengku
Seratus
308800/612900 to
307000/614100
Southern
Rompin
305583/614353 to
305851/614430
Kuala
Pontian
305826/614426 to
305904/614743
296500/625100 to
296000/625600
C3S3M3
295592/625903 to
294753/626212
294621/626108
North Kg.
Tg. Pahang
Kg. Tg.
Pahang
Mainland coast at entrance to Nenasi river
mouth retreating with fallen trees.
Unpopulated
Eroding spit, resulting in sand transported
across spit into river, loss of beach forest
and narrowing spit vulnerable to breaching
Rapidly retreating coast, loss of trees and
coastal forest threatened, backing swamps
buried by overwash, setbacks for chalets
narrowing, mainly undeveloped coast
Short stretch of eroding sector with fallen
beach forest
Failed seawall, small resort threatened,
collapse recently built jetty
Uncompleted resort development threatened
by erosion. Two of chalets damaged by
falling casuarina trees. A river mouth
problem. Problem aggravated by alienation
of sensitive land, especially on newly
forming spit
Coastline retreat and destruction of coastal
forest towards mouth of Pontian river,
undeveloped coast
Houses and land lost and people had
relocated. Wells in the sea. A small resort
and facilities run by Fishermen Coop
damaged. Rock revetment emplaced along
river mouth. A river mouth problem. Some
agricultural land lost to erosion farther to
the east. Low gabion wall recently
emplaced
Retreating coast and loss of beach forest,
forest buffer behind beach and agricultural
land behind
Village and crops threatened. Large
revetment had been emplaced from river
mouth to end of village. Recreational areas
prone to wave overwash and sand burial.
Action taken and no longer a problem
although overtopping of rock revetment
observed.
III
III
II
III
I
I
III
Ex I
III
Ex I
2A7.2.1 Erosion Categories
The different erosion categories are described, with focus on category I. Ex-category I refers to
former critical erosion areas in which mitigation measures employed have been successful in
holding the coastline and erosion is no longer a threat. Where mitigation measures employed have
been less successful or still unproven the original category is retained. There is really no clear
distinction between the various categories with each category grading into another. On the whole
there are relatively few critical erosion sites in South Pahang because of the general undeveloped
state of the coast. As development takes place, a greater length of the coastline will fall into
erosion category I. This is illustrated by the complete absence of either category I or category
erosion in 1985 because much of the coast was undeveloped but since then greater lengths of the
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coastline are classified as critical erosion and various measures have been taken to hold the
coastline. Erosion can be traced to either river mouth dynamics or the downdrfit impacts of
coastal structures. Prior to this study, erosion at Sungai Nibung, Tanjung Tengku, Kampung
Pontian and Kampung Tanjung Pahang had become critical and structures had been emplaced. In
addition, there appears to have been attempts at nourishing recreational beaches.
Category I (Critical Erosion)
Six sites have been identified as category I erosion in which some kind of response in addressing
the problem is required (see Table 7-1). Some of these sites have already been protected by
defense structures or other measures but are still considered category I as the measures taken have
yet to resolve the erosion and its impacts.
The first site is referred to as Twin Hut after the two shelters built for picnickers. In a 2000 aerial
photograph, the car park had already been destroyed but the two shelters were still intact, but
being threatened (Figure 7-1). Sands were being carried inland by storm waves.
Figure 7-1. Erosion had resulted in the realignment of the coastal road, destroyed the car park and
threatened the sheds by the year 2000
By 2005, erosion had completely destroyed the car park and partially destroyed shelter (shed) 2
and beginning to threaten shelter 1 (Figure 7-2). The position of strand materials indicates that
during storms, waves were carrying the sands a fair distance inland.
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Figure 7-2. A 2005 aerial oblique showing the progress of erosion and impacts in Twin Hut coast
The sequence of erosion and impacts, from 2002 to 2005 are illustrated in a series of ground
photographs in Figure 7-3. In June 2002 the car park had been eroded away but shed 2 was intact
and still some distance from the scarp. By January 2005 part of the shed had been destroyed by
erosion leaving two pillars standing. Erosion continued until only one pillar was left standing by
July 2005. Although some may argue that there are little socio-economic impacts resulting from
erosion, it is classified as category I because of the loss of a recreational area and the threat to the
coastal road. Although the alignment of the original road had been reset once, further erosion will
necessitate the road to be relocated once more. Presently, this stretch of coastline is not defended
other than weak attempts to hold it by using slabs of tarmac from the collapsing car park.
June 2002 Shed 2 intact
January 2005 Shed 2- two pillars left
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Year 2006 and beyond???
July 2005 Shed 2-one pillar left
Figure 7-3. Sequence of erosion at Twin Hut
The second site is at Sungai Nibung where several attempts in the past had been made to protect
the coastal road but all unsuccessful. The most recent attempt in mid 2005 is the rebuilding and
extension of the gabion wall and the slight diversion of Sungai Nibung to take the river away
from the gabion. On the November 2000 aerial photograph, the old road had been abandoned, the
old river mouth blocked and the new mouth was deflected downdrift and in the process attacked
the old coast resulting in the partial collapse of the old road into the river (Figure 7-4). No
gabions were or anti erosion structure was observed on the November 2000 aerial photograph.
Figure 7-4. Sungai Nibung river bank erosion attacking the abandoned road in November 2000
In the 2005 aerial obliques of early 2005, a short stretch of gabions which appeared to be recent
in construction had been emplaced along the seaside front of part of the old road but the
structures had started to fail (Figure 7-5). The middle section was peeling away from the road and
collapsing into the river and the northern end had snapped. The unprotected section immediately
to the north eroded badly and slabs of tarmac had collapsed into Sungai Nibung whose mouth had
been blocked off by sand.
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Figure 7-5. River bank erosion and failing gabions at Sungai Nibung in early 2005
This site is classified as category I erosion because the new gabion is similar in design to those
that failed in the past and the end wall looks unstable.
The third site is the unprotected coast downdrift of the water-discharge structure at Agrobest. It is
identified as category erosion I because an economic area is under further threat after ponds were
eroded away in the past. Erosion is caused by the structure located updrift trapping sand. About
one kilometer of coast has been protected but as erosion extends downdrift, more and more of the
coastline will have to be protected to prevent loss of land and ponds (Figure 7-6). The Agrobest
coast has a long history of erosion and attempts were made in the past to stabilize the coastline by
using rolls of wire mesh-a technology from Taiwan. After reports of initial success the attempt
failed and remains of the wire mesh can still be observed half buried in the beach along Agrobest.
Pieces of the wire mesh have been transported downcoast to as far as Tanjung Batu.
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Figure 7-6. Erosion downcoast of the revetted section will result in further loss of ponds
The fourth site is at Nenasi where beach retreat has threatened the road and school (Figure 7-7).
Sand overwash has buried the road which has to be cleared regularly. The whole coastline is
retreating and will continue to do so in the coming years. The immediate problem is the road
which provides some protection to the school but once the road is lost, the beach will rapidly
retreat and threaten the school. A high scarp separates the road from the beach which appears to
have been nourished in the past. Farther towards the spit, fences protecting planted casuarina trees
have been partly destroyed by erosion. Strong wind action also carries sand from the beach inland
and aggravates the deficit in sand budget. During August 2005 Sungai Bebar (Nenasi) was being
dredged and some of the sands were dumped along the spit front to renourish the beach. The
renourished beach lies downcoast of Nenasi and although some sands are transported northwards
during the southwest monsoon, the net littoral transport is southwards. Sands should be trucked
north of Nenasi Town so that wave action and longshore currents will carry the sands to the
eroding beach in front of the school. The critical erosion site and renourished beach is shown in
Figure 7-8.
Figure 7-7. Erosion at Nenasi threatening the local road and school
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Nenasi category I erosion
Beach nourishment
Figure 7-8. Beach erosion and nourishment at Nenasi
The fifth site is at Tanjung Tengku at the northern bank of Sungai Rompin (Figure 7-9). Erosion
has damaged a small resort previously run by the Fishermen’s Cooperative and a short sea wall,
the toe protected by small boulders, was emplaced in 2004. The sea wall, especially both ends,
failed. Undermining is a contributing factor. This is a muddy coast with a thin veneer of sands
over it. The soft underlying mud has also caused the failure of the jetty. In the absence of the
small resort, erosion would have little impact. It is a case of locating a building without proper
consideration of the coastal dynamics. Erosion is not new as there were several old anti-erosion
structures in the vicinity and an old concrete culvert has also been stranded on the beach
indicating coastline retreat. The site is considered category I erosion despite attempts to hold the
coastline by building a sea wall with an armoured toe. The structure has failed completely.
Southern end
Northern end
Figure 7-9. Category I erosion site at Tanjung Tengku
The sixth site is at Tanjung Seratus at the southern bank of Sungai Rompin. The site became an
erosion problem only after a Phase IA development, consisting of 208 units of service apartments,
was being built on a vulnerable site at Lot 215. Before the development was completed two
buildings were damaged by fallen casuarina trees and others threatened by erosion (Figure 7-10).
Erosion is severe as evidenced by the long line of fallen casuarina trees littering the shore and the
extensive sand overwash taking place. Work on the project stopped for a while but later resumed.
The erosion problem is attributed to poor choice of development site. Erosion is related to river
mouth dynamics and difficult to contain. The buildings were erected on a raised building platform
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and this may help to prevent flooding but not erosion. Anti-erosion structures will have to be built
by the developer to prevent loss of property and building. However, whether structures will
contain the river bank erosion is uncertain.
January 2005
July 2005
Tongues of sand from wave overwash
Damage caused by fallen casuarinas trees
Figure 7-10. Uncompleted service apartments threatened by river bank erosion
Ex-Category I
Ex-category I erosion refers to former critical erosion sites in which measures taken have been
successful so that there is no longer any threat to property, infrastructures and human life. These
were previously identified as critical erosion sites after the 1985 NCES study.
The first site is Pontian where river mouth erosion has caused severe damage to property, land
loss and threaten the road leading to Kampung Pontian. In response, the river bank was revetted,
houses relocated and more recently a low gabion wall emplaced behind the beach (Figure 7-11).
The river mouth is slowly migrating in a southward direction and holding the position of the
southern bank only would only mean that the river mouth will become narrower and narrower
and more flow energy will be concentrated along the bank where the village is located. Erosion
along the beach front is of less concern as there is no settlement there but lateral access along the
beach is impeded during high tide. The strong wind action aggravates erosion as sands are taken
out of the beach system and blown inland.
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Figure 7-11. River mouth erosion at Sungai Pontian
Several wells can be seen on the beach and in the inter-tidal area (Figure 7-12). The building
wastes from the abandoned houses were used as temporary revetment to hold the coastline. Some
erosion still persists and the low gabion wall may not be very effective. However, no houses are
being threatened and the area can be taken off the list of category I erosion.
Erosion and relocation of houses
Response
Abandoned well- low tide
Abandoned well-high tide
Figure 7-12. Former critical erosion sites where houses have been relocated
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The second ex-category I erosion site is Kampung Tanjung Pahang, at the northern side of Sungai
Endau (Figure 7-13). There is no relocation of houses here but a massive revetment was emplaced
in front of the old coastline to protect the village. This is an example of a former critical erosion
site being taken off the list because of the successful anti-erosion measures taken. On the
downside the beach in front of the rocks has been lost.
Figure 7-13. Revetment has successfully addressed the critical erosion site at Kg. Tg. Pahang
The undefended coast to the north is mainly agricultural land and shoreline retreat will have a
much lesser socio-economic impact but anof some concern though is the local park recently
developed by the river bank (Figure 7-14). This is a sensitive site, subjected to sand overwash
which is becoming a problem. Small patches of mangroves in the vicinity of the park are also
being eroded away. Monitoring is recommended here.
Undefended southern end- park
Undefended northern end-rural agriculture
Figure 7-14. Erosion and sand overwash along undefended coast on either side of the revetment
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Category II (Significant Erosion)
Two stretches of coastline have been classified as having significant erosion in which monitoring
is recommended to assess whether there will be future continuous retreat in which the ensued
socio-economic impacts will have to be addressed.
The first is the Hiburan Pekan coast, a long stretch of coastline from the present blocked mouth of
Sungai Miang to the eroding Agrobest coast. The retreating coastline threatens the coastal road
which runs very close to the sea in places (Figure 7-15) and monitoring is required so that preemptive action can be taken before the road is damaged.
Figure 7-15. Category II erosion along the Hiburan-Pekan coast
Farther to the south after the critically eroding Sungai Nibung coast is Pantai Hiburan. A high
scarp which runs from Sg. Nibung to Agrobest now separates the land from the sea and access to
the beach can be difficult (Figure 7-16). Several abandoned and damaged houses were found near
the beach. The reason for the abandonment of Kampung Dua Belas and houses is not clear. Pantai
Hiburan is a popular picnic and camping area for family groups. Several tracks lead from the
main road to the beach. Pantai Hiburan-Pekan is considered category II erosion although no
formal infrastructures or buildings are threatened because it is an important local recreational
space and should be protected
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Figure 7-16. A high retreating scarp lies at the back of the beach at Pantai Hiburan-Pekan.
The coast from Pantai Hiburan to Agrobest is severely eroding (Figure 7-17). A narrow strip of
land now separates the sea from the ponds and buildings. Monitoring is recommended to plan the
next course of action should shoreline erosion become more severe.
Figure 7-17. Category II erosion at Pantai Hiburan-Pekan and Agrobest
The second category II erosion coast is Summerset where recent erosion has toppled coastal trees,
narrowed the beaches and started to threaten the resort structure (Figure 7-18). The setback of the
buildings is less than 60m from mean high water and sands are washing across the coastal scarp
into the resort areas. Beach buggy activity is curtailed by the narrow beach and also by toppled
trees lying across the beach.
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Figure 7-18. Category II erosion at Summerset, where further shore retreat will adversely affect
beach quality and threaten resort structures
Category III (Acceptable Erosion)
The major category III erosion areas have been listed in Table 7-2, but shorter stretches of similar
category have not been documented. Except for a few locally accreting sectors, the remaining
coast of the south Pahang is in retreat. In general, coasts not identified as category I or category II
can be considered to be category III. Many of these category III are marginal category II or
potential category II. Retreating undeveloped coast once developed will quickly be converted to
areas of significant erosion or worse still areas of critical erosion. This is already happening when
development takes place behind the beach without adequate setback, without consideration f the
changing coastline or where newly accreting land has been alienated out into private ownership.
Selected category III erosion coasts are illustrated and described below. A wide range of coastal
conditions are selected to characterize category III. These include migrating spits, erosion related
to river mouths, erosion along straight coasts with a sand budget deficit and undefended coasts.
The impacts include loss of beaches, loss of trees and potential loss of agricultural land and rural
roads. Erosion tends to extend downdrift and brings an increasing length of coastline into the
erosion category. In the NCES 1985 study, all the 41.7 % of the retreating South Pahang coast
was considered category III erosion.
The Pahang spit migrates shoreward and in the process sands are carried from the beach face and
deposited into the lagoon. As a consequence beach forest is initially buried and toppled followed
by exposure of mangrove on the ocean front and eventual loss of mangrove forest as the sand
body migrates across the lagoon (Figure 7-19). In the mid section of Pahang spit, the spit had
been destabilized after a phase of stability where beach forests of casuarinas trees colonize the
sands and mangroves encroach into the lagoon. When the sand body starts to migrate shoreward,
the beach forest is lost first and at a later stage the mangroves are buried by sand and eventually
killed. There is no danger of category III erosion here becoming category II because it is difficult
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to envisage any anyone converting the spit into a development area after the lesson learnt in
Pantai Sri Tujuh on the Tumpat spit in Kelantan. The whole of the Pahang spit should be left
untouched.
Figure 7-19. Category III erosion towards proximal end and mid section of Pahang spit
The undeveloped coast just south of the entrance to Sungai Bebar is retreating and fallen trees lie
scattered along the narrow beach (Figure 7-20). Sands are washed inland by storms burying the
outer fringe of the coastal forest. Erosion is probably related to discharging water of Sungai Bebar
during floods. The coast, isolated and not accessible from the landward side, is expected to
remain undeveloped in the near future. As the Bebar spit extends southwards, this sector will
become protected from wave attack and new areas downcoast will begin to erode.
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Figure 7-20. Category III erosion south of Sungai Bebar entrance
A similar situation as that above is found south of the Sungai Mercung river mouth where
discharging water has cut back the coastline resulting in extensive loss of the coastal forest
(Figure 7-21). Wave attack on the narrow beach has washed sands into the forest fringe and
buried some of them. A line of dead trees caused by burial and tidal inundation fringes the coast.
There is difficult lateral access along the beach during high tide because of the fallen trees.
However, there is no socio-economic impact as the coastal zone is also undeveloped because of
the swampy terrain and difficult access. No development is expected here in the near future.
Figure 7-21. Category III erosion sites with negligible or no socio-economic impacts south of
Sungai Mercung
North of Summerset resort the coastline shows severe erosion, with sands being washed across
the narrow beach into the backing swamp which is contracting in size (Figure 7-22). Sand
overwash is very active taking place during high spring tide or during storms. This area is just
north of Summerset Resort and as erosion extends down coast this kind of shore retreat will arrive
at the resort, bringing with it severe economic impacts.
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Figure 7-22. Beach retreat across backing swamps north of Summerset
Tongues of sand invading into the swamps are clearly evident on the ground, and in time the
swamp will be completely filled up resulting in the loss of what may be an important swamp
habitat (Figure 7-23).
Contraction of swamp caused by sand Severely erosion
overwash
economic impacts
but
with
insignificant
Figure 7-23. Category III erosion north of Summerset Resort
The undeveloped southern portion of Rompin coast near the mouth of Sungai Pontian is eroding
and trees toppled into the sea as the shoreline cuts back (Figure 7-24). Fortunately the coast is
mainly inaccessible and there is no settlement or resort development. Lots are, however, being
alienated north of Rompin Beach Resort and agricultural development and there is a plan for a
school to be sited there. The erosion appears to be severe based on the large number of trees that
have recently toppled into the sea. Any development plan for this coastal sector must take into
consideration the retreating coast by having an adequate setback. Otherwise the coast will soon be
reclassified into category II or even category I erosion. When new coastal land is being alienated,
it is imperative to retain a coastal strip of state land of at least 60m wide as a buffer. In fact for a
retreating coast such as in south Rompin, it would be prudent to have a wider reserve.
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Figure 7-24. Retreating coast south of Rompin Beach Resort near Sungai Pontian
The whole length of the Kampung Pontian-Kampung Tanjung Pahang coast was documented as
category III in 1985. Since then Tanjung Pahang has been reclassified as category I and the
development of small beach-front resorts will turn some of them into category soon because the
coastline continues to retreat although serious erosion with a large number of trees lost to the sea
was not observed. Three coastal sectors with category III erosion are illustrated, with one of them
on the verge of being reclassified as category II erosion.
The first sector is the abandoned PESONA camp coast which has a good sea view with the
Ducung Islands offshore. The coast shows some retreat and the local road runs close to the beach
(Figure 7-25). There is no evidence of active erosion. The flat beach is narrow-medium but there
is no clear evidence of overwash or loss of trees..
Figure 7-25. Abandoned PESONA camp
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The fence line of the abandoned PESONA camp lies just behind the beach and a survey of the
camp area did not find wave overwash or tidal flooding (Figure 7-26). The coastal forest and
beach flora were intact. However any initiation of erosion would have threatened the
infrastructure of the resort. Should there be any revival of the camp; a proper setback should be
instituted.
Looking north-no evidence of overwash
Property line close to the beach
Looking south-intact beach forest
Abandoned PESONA camp
Figure 7-26. Recent small resort/camp development on previously undeveloped coast
Farther to the south is the small development of Chalet PN Rompin (Figure 7-27). This is a beach
front property with wave overwash along the two accesses to the beach on either side of the
chalets. The undisturbed beach forest away from the chalets looks intact but is thin in the area of
the chalets. The beach is very flat and narrow in places. The property line of the chalets runs just
behind the beach. The buildings are, however, set a fair distance back from the beach.
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Figure 7-27. Category III erosion with high prospect of becoming category II
The coastline has stabilized and the flat upper beach is being invaded by beach morning glory.
The long trailing creeper suggests that the beach has been above tide inundation for the last few
months (Figure 7-28). The beach was in retreat in the past and several tree stumps still remain on
the upper beach. The flat beach makes the chalets highly vulnerable to erosion and this coastal
stretch of category III erosion can easily become category II) or even category III.
Figure 7-28. Category III erosion in front of Chalet PN Rompin can easily become category II
erosion.
Near Kampung Tanjung Pahang just before the revetment, the undefended coast is retreating
across agriculture and grazing land (Figure 7-29). Although there is some economic loss the
threatened or lost land is of low value. The coast has been classified as category III erosion or
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marginal category II erosion, especially the coast where grazing land has been lost. Farther inland
are market gardens. Any large scale development near the sea will have to address the erosion. A
low retreating scarp separates the land from the narrow beach and storm waves transport strand
materials over to scarp to deposit them inland. The area should be left as it is.
Figure 7-29. Undefended coast just north from Kampung Tanjung Pahang revetment
2A7.2.2 Causes of Erosion
The general cause of beach erosion in South Pahang should be attributed to a global phenomenon
and not the result of local sources. Beaches worldwide are retreating and the beaches of South
Pahang are no exception. Sediment supply for beach construction in South Pahang is fluvially
derived and dependent on upstream activities which may augment or diminish sediment supply.
Although tidal monitoring does not indicate a positive mean sea level trend, this possibility
should not be completely discounted. Human activities, however, may also adversely affect the
sediment budget locally.
The causes of erosion in South Pahang are usually associated with river mouth dynamics which is
complicated by the southward migrating mouth for rivers deflected by spits or where attempts
have been made to hold one bank without addressing the problem on the other bank, as in
Kampung Pontian. As the river mouth migrates, discharging water during floods are also
transferred southwards and erode new areas. The pattern is a gradual southward extension of
erosion with former eroding areas becoming protected by elongating spits. Erosion along
Agrobest is human-induced. Various actions there have contributed to erosion, the major ones
being the removal of sands from the beach in the early days to construct the ponds. It is claimed
that permission was obtained from the authorities for this. The severe erosion resulted in the loss
of a small company gold course, loss of ponds and land and several failed attempts were made to
hold the coastline. The construction of a water discharge outlet extending into the sea acted as a
groyne, trapping sand and starving the downdrift sand of sand supply. Inevitably the downdrift
coast started to erode badly and had to be protected a long revetment of quarry stones. The beach
in front of the wall was lost. The Sungai Nibung critical erosion has along history and again
attempts to open up a channel to drain flood waters may have inadvertently directed the rushing
water southwards towards the road. The threatened road was armoured by gabions which was
ineffective. The most recent attempt was to redirect the river back to its original outlet and divert
it away from the line of gabions protecting the road.
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Physical erosion is just one dimension when examining the impacts and socio-economic cost. An
even more important dimension is development in sensitive areas, where the coastline is highly
dynamic or retreating. In 1985, none of the eroding Southern Pahang coast was classified as
category I or category II because erosion did not result in socio-economic losses due to the
general undeveloped character of the coastal zone then. The scenario has changed and several
sites are now considered critically eroding. Some are because of river mouth dynamics which are
unavoidable but of great concern is the siting of development in sensitive areas. A case in point is
Seratus. This is avoidable and should not happen. A properly instituted and implemented
shoreline management plan will go a long way in preventing such poor siting.
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