Embed Size (px)
DESCRIPTION
An assessment of Miri Coastal environment
Citation preview
1
1.0 General
A study was carried out along 15 km of Miri’s northwest facing coastline covering the areas
of Luak Bay Esplanade (LB), Marina Bay (MB), Piasau Peninsular (PP) and Tanjong Lobang (TL).
This report will present the observations, records and evaluations of the coastal processes
occurring in the region besides weighing the impact of those processes to the human population.
2.0 Geology
The areas studied have similar Miri formation geology and are mostly covered by Neogene
sediments. This formation is predominantly sandstone with moderate-‐poor cementation and is
highly susceptibility to physical weathering processes. Exposure in TL and LB Esplanade headland
suggests that the sedimentary strata are moderately dipping and is affected by joints and faults.
Besides having rocky coast, the coastline beaches are mostly unconsolidated and have low relief.
White to brownish, very fine to fine detrital sands can be found along the major coastline. These
sediments are affected by tidal activities, and rigorous wave and wind actions.
3.0 Topography and geomorphology
Miri’s coastal region has a wide topography range due to the complex geology of the
underlying rocks and the variation in elevation and dip along the coast. Depending on the chemical
properties and the degree of hardness of the rock along the shore, coastal processes of various
magnitudes, such as destructive waves, longshore drift currents, surges and strong winds can effect
the formation of coastal landforms. During this study, the major landforms seen along the coast are
headlands, bays, sea caves and beaches.
2
Five profiles (shown in the next page) of TL and LB Esplanade beach were made to study
the coastline’s geomorphological variation. Indeed, different backshore and foreshore profiles were
seen as a result of tide level and wave energy fluctuations along the coast. Consequently, this affects
the waning process of suspended sand particles via wave actions, which then leads to deposition of
sediments at different locations along the coast. The different width and location of the beachfaces
in all the profiles exemplifies this fact.
4.0 Drainage (hydrology)
Both artificial and natural drainage are present at the study area. These drainage systems
are responsible to bring in water from natural flows and run-‐off to the coastal sides. Miri River and
Sg. Buloh are the two main natural drainage systems encountered in the study. These rivers have
very high flow rates, and records in Sg. Buloh show an average flow of 156 L/sec.
Figure 1: Tanjung Lobang Beach Geomorphology
3
Artificial or man drainages can be found in TL, LB Esplanade and MB. These drainages
channel surface waters from nearby residential and recreational area to the seaside. In contrast to
natural drainage, these drainages have lower flow rate. In TL, the flow average rate of the drainage
system is 77 L/sec. Another type of artificial drainage called storm drainage can be observed in MB.
It serves as an outlet of storm water from the city’s underground drainage network.
5.0 Vegetation
Various types of vegetation are growing in Miri’s coast. Listed below are the vegetation seen along
the coast:
Location Vegetation Note
TL beach (pioneer
zone)
Beach Morning Glory, Ipomoea
pes-caprae
Has purple-‐pink flowers,
Penetrate as far as 10 meters in land
TL, LB inland, MB Herbaceous, shrub species and
woody species
e.g. Casuarina littoria, Mimosa
pudica , Mengkuang(Pandanus
odoratissimus) and coconut tree.
Salt sensitive species, Intolerate wave
disturbance and sand movements.
Some woody species are planted to
stabilize coast and abate erosion.
PP Nipah Palm Possibly washed ashore from Kuala
Baram. Salt tolerant plants. Table 1: Coastal Vegetation in Miri
Figure 2: Casuarina littoria
4
Figure 3: Mengkuang (Pandanus Odoratissimus)
Figure 4: Coconut Tree
5
6.0 Miri Tide Analysis
Figure 5
From the graph and table above, the highest tide during FM and NM are in the afternoon.
At this time, the gravity of the sun and moon combines together and pull vertically from the
location. The lowest tide is in the evening because the gravity of the Sun and Moon pull
across the location. FM and NM produce maximum gravitational forces, hence creating the
highest and lowest tides of the month (spring tides). In this study, spring tide occurs when
the tidal range is greater than 80cm while neap tide happens when the tidal range is
smaller than 80cm. The dates of spring and neap tide occurrences are show in table.
Spring tides occur around a week before the FM and NM whereas the neap tides , occurs
approximate 2 to 3 days before the First Quarter and Last Quarter. Full Moon and New
Moon have greater influences than the First Quarter and Last Quarter in Miri, as there are
only 9 neap tides and 22 spring tides in August 2010.
0
50
100
150
200
0 5 10 15 20 25
Tida
l hei
ght(c
m)
Time
Tidal information of August' 10 (Miri)
last quarter(july)
new moon(aug)
First quarter (aug)
6
Figure 6
The tidal cycle of Miri can be classified as mixed dominantly diurnal cycle. There are 17
days of diurnal cycles, 2 days of semi-‐diurnal cycles, and 12 days of mixed tide cycles. The
diurnal cycles occur together with the spring tides while mixed tide cycles occur together
with neap tides. Semi diurnal cycle is infrequent in Miri, as they only happen twice in
August during the transition of spring tide to neap tide.
The lowest tidal range is 40cm on 1st August, and the greatest tidal range is 172cm on 10th
August. Since the greatest tidal range is not more than 200cm, Miri beaches can be
classified as wave dominated beaches, due to the microtidal range.
0 20 40 60 80
100 120 140 160 180 200
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Tida
l hei
ght (
cm)
Date
Miri Tidal Chart August' 10
Types of tide Date (August 10) Number of days
Diurnal tide 3,4,5,6,7,8,9,10,16,17,18,19,20,21,22,23,31 17 Semi-diurnal tide 14,28 2 Mixed tide 1,2,11,12,13,15,24,25,26,27,29,30 12 Classification of cycles
Mixed dominantly diurnal
Tidal range Microtidal (<2m)
Table 2: Miri Tide Range
7
6.1 Regional Comparison
Figure 7
The table and graph above show the tidal information of Northwest Borneo on August 10,
2010 (NM). The spring tide ranges of Bintulu, Miri and Kota Kinabalu are below 200cm and
can be classified as microtidal. These locations are wave dominated and have similar tidal
range (< 200cm). On the other hand, Labuan’s tidal range exceeds 200cm. Thus, it is has
mesotidal range and is more likely to be influence by wave dominated processes due to
considerably low tidal range.
Location Tidal range (cm)
Classification
Bintulu 170 Microtidal Miri 172 Microtidal Labuan 207 Mesotidal Kota Kinabalu (K.K) 184 Microtidal
Table 3 Northwest Borneo Tidal Range
0 20 40 60 80
100 120 140 160 180 200
heig
ht
time
Full moon Aug 10
Bintulu
Miri
Labuan
K.K
8
7.0 Human Activity
The coast of Miri has been bustling with human activities. Besides being a home to a large
population, major trading activities occurs along the coast. Shipping and transportation of
industrial products, logs and other local exports were seen in Lutong and Baram. In the offshore
reaches of TL and Lutong, West Baram and Tukau Platforms were erected to extract crude oil and
gas from the marine subsurface. Industrial estates are being developed to provide job opportunities
to the growing population besides generating economic income for the region.
Recreational activities also form the major human activity in the coast. In PP, for instance, a
golf and a boat club was built for recreational purposes in the area. TL and LB has also been a
tourist spot and a well-‐known weekend retreat for many of the human population. High-‐class hotels
have been built in TL to enhance the tourism attraction of region. Diving, jungle tracking, yachting
and water sports are some of the tourism activities offered to visiting tourist.
Figure 8: Various offshore activities are taking place along the coast of Miri. (a) Oil and Gas Platform for oil extraction (b) Transhipment of Logs (c) Loading of shipment for shipping (d) Offshore view from Piasau Beach
9
Apart from that, local fishermen fish various marine products along the coast and their
captures were then sold at local markets in Lutong and PP. Agricultural activities seen includes
coconut plantation in LB, palm oil plantation and vegetable farm close to Kuala Baram shore.
7.1 Man Made Structures
Following below is a record of man made structures in the study area:
Tanjung Lobang
Marina Bay Luak Bay Esplanade
Piasau Peninsular-‐Pulau Melayu-‐Lutong
Coastal Defense Rip rap ✓ ✓ ✓ ✓ Gabion ✓ ✓
Groynes ✓ ✓
Sea wall ✓
Vertical Bulkhead ✓ ✓
Infrastructure
Roads ✓ ✓ ✓ ✓ Bridges ✓ ✓ ✓ Mosques, Churches ✓ ✓ School ✓ ✓ ✓ Community Center ✓ ✓ Power House, Transmission station, Telecomunication hub
✓ ✓ ✓ ✓
Storage, warehouse, stockplace
✓ ✓
Oil and Gas Facilities ✓ ✓ Jetty, Docking and Maintenance facilities
✓ ✓ ✓
Drains, Storm gates ✓ ✓ ✓ ✓ Recreational Facilities ✓ ✓ ✓ Public Amities (toilet, fire ✓ ✓ ✓ ✓
10
hydrant etc.) Others (specified)
Tidal Station
Buildings
Shop houses, Restaurants ✓ ✓ ✓ ✓ Market, Marts ✓ ✓ Offices, regional operation center
✓ ✓
Villages houses, Squatters ✓ Residential Houses, Apartments, Quaters
✓ ✓ ✓ ✓
Beachfront bungalows, villas, mansion.
✓ ✓ ✓
Resorts, Hotel, Club Houses
✓ ✓ ✓
Table 4: Miri Coastal Man Made features
✓ = structures present
As a whole, the densely populated coast of Miri has been developed with many
infrastructures to enable various human activities. Areas of TL and the PP, Pulau Melayu and
Lutong have the most number of facilities and infrastructures compared to LB and MB. This means
that these areas are more vulnerable towards coastal processes and requires more coastal
protection measures.
11
Figure 9: Different coastal protection measures in Miri.The revetments prevent erosion along the coast by increasing its rigidity and resistance towards tidal and wave forces. (A) Gabions in Tanjung Lobang. This protection is not very effective to hold erosion in Tanjung Lobang. Furthermore, it is also hazardous and promotes unsightly view to tourist. (B) New seawall along Tanjung Lobang beach (C) Groynes at Tanjung Lobang were build to help nourish the eroding beach besides acting as a wave breaker (D) Rip rap construction in Marina Bay outline the newly reclaimed land.
12
Apart from being a yachting and sailing destination, MB is also a form of protection as it
shields the town of Miri from wave activities. The infrastructures currently on the marina include a
seahorse statue, a seafood restaurant, docking facilities, and a view-‐watching area at the edge of the
marina. Figure 12 suggests the future plans for the marina park, which includes a city hall, a
residential area and a hotel (n.a 2005).
Berthing / Docking area
Groyne
RipRaps
Run-off area
Channel
Shield to City Limit
Figure 8 : Marina bay coastal defense. The shape of the marina entrance is designed with the idea of keeping wave currents at a minimum; to enable easy berthing of yachts. Rock revetments minimize and absorb wave energy to prevent the coast from severe damages
13
8.0 Key Issues for Sustainable Coastal Management
Given below are the problems faced to sustain Miri’s Coastal Management plan
1) Coastal Erosion
According to a study by DID, Miri’s coasts are highly exposed to coastal erosion especially in those
areas facing South China Sea like the 12 km long Piasau peninsular and Luak Bay. These areas
receive strong wind, waves and storm surges throughout the year (DID 2000). This results in sand
loss and may affect the whole sand budget along the coast. Extreme waves and storm surges force
sand bars to move seaward and the sand loss may lead to narrowing or steepening of the beach
profile.
Figure 9: Plan view of proposed development in Marina Bay
14
2) Reclamation Projects
Miri’s coastal sides have been reclaimed and dredged over the past 10 years to build a marina city.
This attempt was made to boost tourism attraction besides shielding Miri city centre from coastal
processes. The reclaimed land was built using hard rocks and marine sediments at approximately
8-‐10 m above sea level. At the same time, Miri River passageway was diverted to give way to the
construction projects.
The increase in land area means larger areas would need coastal protection. Hence, this would
increase the cost to implement protection measures. It is feared that this mega-‐construction project
would interrupt sand supplies from long shore currents and from natural river flows that could
trigger erosion on other parts of the region.
Figure 10: The new Miri river path and Miri Marina (in circle) location which was built on a reclaimed land.
New river path
15
3) Rapid Urbanization and development along the coast
Rapid urbanization and development has now encroach the coastline of Miri. More housing
projects, squatters and beachfront properties are being built along the coast. As a result, this
increases the number of population exposed to the threat from coastal processes and hence,
demands for a wider-‐scale protection. Besides that, human activity and artificial stabilization of sea
front may also contribute to the increase of coastal erosion process in the region.
Figure 11: Evolution of Miri and its coastal morphologies. In just within two decades, rapid urbanization and development took place along the coast. A river diversion and a more densely built infrastructure are the obvious changes seen.
4) Pollution
Various pollutants have contaminated Miri’s coastal region. Most of the input of these pollutants
came from Miri River; which is responsible to transport commercial and industrial pollutants,
construction waste, agricultural by-‐products and waste generated by illegal tenants along the
riverbanks to the coastline (DID 2000). Masses of floating wood-‐mill debris have covered a massive
area of the beach in Piasau Peninsular due to the processing and transshipment of timber in Baram.
Illegal dumping of construction materials were also seen near the storm gates of the city center.
16
This problem could be further alleviated by offshore oil and gas extractions and various shipping
activities along the coast
5) Type of Protection used.
Artificial nourishment of beach, constructions of revetments like rip raps, sea wall, gabion, groynes
and vertical bulkheads are some of the measures taken to counteract the effects of sea level rise,
storm surges and coastal erosion in Miri.
However, some of these methods are still ineffective to withstand the force exerted by nature. In TL
and LB Esplanade, new piles of revetments have to be made in front of the old revetments to
function as new wave breakers. Conventional construction of vertical bulkheads such as those
found in Tg. Lobang and the Piasau Peninsular, meanwhile, are only partially effective as it works
only in limited period and space as it increases turbulence and sediment scouring (Sumer 2001).
These hard constructions result in a “coastal squeeze” process that forms steep beach profile and
shrink the size of natural habitats (Doody 2004).
9.0 Key Threats and Potential Impact to Coastal Environment and Human Population
Following below is an account of the major threats faced by the region:
1) Infrastructure and Property Damage
As mentioned, the urbanization of Miri has brought developments of infrastructures along
the coast. Despite the strategic location and scenic views, these developments have to face the
coastal erosion effects and cope with the erratic weather patterns like surge storms, gale, huge over
wash and rising sea levels. As a result, this would hinder numerous human activities along the coast
especially fisheries, transportation of goods, marine services, local businesses, tourism, and
regional operations. Landward migration of coast results in lost of development areas along the
coast.
2) Degradation of natural ecosystem
One of the biggest concerns related to the changing shoreline is the degradation of natural
ecosystem. The obvious threat in this sense is the lost of important habitats around coast. Miri is
known as an important stop for migratory birds, and a natural habitat for Humpbacks and Irrawady
dolphins, crocodiles and other amphibians. Coral reefs also thrive along Miri’s coastline to support
17
the marine fauna in the region. However, amplification of natural processes through climate change
and human activities pile stress to the coastline region. This is portrayed by the dwindling size of
wetland areas through reclamation project and agricultural land conversion along the Baram
Coastal Highway and MB. This is further worsened by the increasing amount of industrial pollutant
like oil and wood mill by-‐products along the coastline. Meanwhile, intense coral bleaching also
takes place due to increasing sand in-‐flux from the coastline and from Baram hinterland. Marine
sand dredging from offshore Miri also destroys the coral population and other “bottom-‐dwelling”
marine faunas such as the mollusks.
All this damages would threaten the source of food and water supply for the region’s human
population. Removal of important physical barriers and chemical buffer zones along the coast
threatened the utility water sources and food supplies obtained from agricultural and aquacultural
activities. Simultaneously, major transportation and trading activities would be frequently halted
by surges and violent storms.
In a wider context, the coastal protection measures in Miri demand for a great supply of
construction materials. Voluminous amount of limestone, igneous rocks, steel and concrete
aggregates is needed for Miri’s coastal defense construction. This has to be extracted and
transported from numerous in-‐land sources like Subis, Batu Gading, Matang and Sabah. To some
extend, the quarrying and the transportation of these materials will bring harm to the environment
since these activities are known to cause air and water pollution, groundwater drawdown, mass-‐
wasting and massive land clearings. These will then affects the in-‐land surrounding communities
through annual disasters such as floods and landslides, ancestral land issue, chronic health and
safety issues as well as displacement of major in-‐land population. Another concern regarding the
measures taken is the possible knock-‐on effect of erosion to adjacent areas. This means that human
settlement along the coast of Bakam, Bungai and Tusan are also vulnerable to amplified effects of
coastal erosion.
The table below summarizes the key threats, agents and the communities affected:
Key Threats Agent Coastline Communities
Affected
Property and
Infrastructure Damage
from Erosion
Natural Processes
Knock-‐on effects from coastal
defense
Regional operations especially
offshore service provider and
oil and gas companies,
18
fishermen, tourist operators,
beachfront property owners,
and local settlement.
Lost of Natural Habitat Coastal Development projects
Land conversion
Quarrying of construction
materials
Sand Dredging
Coral Bleaching
Saline intrusion
Tourist operators, local
communities practicing
traditional activities,
aquacultral and agricultural
operators, various in-‐land
populations.
Diminishing of Buffer
Zone
Land conversion
Reclamation projects
Housing development
Agricultural and Aquacultural
Operators, Miri’s coastal
residents.
Environmental
Pollution
Release of Industrial
Pollutants
Oil and Gas Extraction
Shipping
Entire coastal population,
Tourist operators,fishermen
and other aquaculture
operators Table 5
10. Conclusion
Miri has a microtidal range and its coastal geomorphological features are highly influenced by wave
activities.
The evolution of Miri can be seen from the drastic geomorphological change of the coastal zone
brought by development along the coast and the implementation of rigid coastal defense
mechanism. Despite this changes, Miri’s tussles with erosion and other natural process remains the
same. Unless a suitable engineered solution is found, Miri’s natural coast and population are
vulnerable to the threat of infrastructural damage and destruction of natural ecosystems.
(2988 words)
19
Reference:
B. Mutlu Sumer 2001. Scour Around Coastal Structures: A Summary of Recent Research . Coastal Engineering , 153-‐190.
Department of Irrigation & Drainage Sarawak (DID). 2000. http://www.did.sarawak.gov.my (accessed August 31, 2010).
Pat Doody, M. F. (2004). Living with Coastal Erosion in Europe. Luxembourg: European Communities.
Resources:
Tidal info
Office website for Department Survey and Mapping Malaysia, http://www.jupem.gov.my (accessed August 10, 2010).
Coastal Geomorphology
Engineering and Design: Coastal Geology. 1995. Washington: Department of the Army U.S. Army Corps of Engineers, DC 20314-‐1000 Others:
Sarawak Dolphin Project.2007 http://www.ibec.unimas.my/SDP2008/index.htm
Figure sources:
Figure 10, Miri Marina 2005, http://www.mirimarina.com (Retrieved September 15, 2010).
Figure 11, http://malaysiawaterfront.blogspot.com (Retrieved September 15, 2010)..
Figure 12, Garmin MapSource.
Figure 13, Typhoon Studios
