a holistic approach in coastal management

a holistic approach in coastal management

THE BEACH REHABILITION AT PULAU TIOMAN, MALAYSIA

Khor Chai Huat1and Dr Lim Foo Hoat2

Managing Director1and Director2,

Angkasa Consulting Services Sdn Bhd, Malaysia

Email: kch@acssb.com.my and fhlim@acssb.com.my

Abstract

Tioman island is one of Malaysia’s premier tourist locations and a National Marine Park Teluk Tekek is its main entry point by air and water This project to rehabilitate the Teluk Tekek coastal area is significant in that for the first time in Malaysia coastal management issues have been addressed concurrently in an integrated manner It represents a major shift in approach in coastal management in the country The solutions adopted have resolved a host of engineering, environmental and social issues in one single turnkey project

Tioman island is a Marine Park surrounded by sensitive coastal ecosystem with coral reefs It is located in the South China Sea subjected to high waves, current and storm surge The project calls for a high degree of understanding of the coastal processes and sound engineering judgment It has employed soft engineering approach to ensure the long term sustainability of the beach, minimize the impacts on the marine environment and preserve the natural beauty of the coastline The Project has resolved the beach erosion, river mouth, siltation, river pollution, navigation and boat mooring problems The successful implementation of the project has dramatically changed the image of Teluk Tekek and has improved the socio-economic condition

of the local community

Pulau Tioman is one of Malaysia’s premier tourist locations and is well known internationality In the 1970s, TIME Magazine selected Tioman as one of the world's most beautiful islands [source: Wikipedia].The island was gazetted as a National Marine Park in 1994 and accorded a duty free island status in 2002.to boost the tourism industry

Teluk Tekek is the main entry point by air and sea to Pulau Tioman There are chalets, private properties, jetty, customs and immigration offices etc located along the beach front and airport is located nearby Teluk Tekek faced severe coastal erosion The construction of flex slabs revetments along the beach had rendered the beach unsuitable for recreational activity (Plate 1) The conditions had degenerated to a poor state due to uncontrolled developments, squatters, river and sea pollution problem (Plate 2)

Hence, instead of being awed by breathtaking scenic beauty upon their arrival by sea or air, the tourists are greeted with the untidy scene of boats scattered randomly, solid wastes, and unsightly squatters clustering along the Tekek river banks These problems are detriment not only to the beach for recreational purpose but also detriment to Pulau Tioman as an island of tourism

Plate 1 - Erosion has caused loss of

beachfront and endangered properties

In order to overcome the above-mentioned problems and also to assist in the development of tourism industry in Pulau Tioman, the Government has decided to implement the project to rehabilitate the beach and coastal areas Figure 1 shows the project location and Figure 2 the satellite image of project site

Teluk Tekek is bounded by Tg Mesoh headland in the north and Tg Said headland in the south

It has a total catchment area of 7.5km2, consists of four very small river catchments, namely, Sg Air Hantu, Sg Tekek, Sg Batang Sabut and Sg Tanjung Said Figure 3 shows the zoning and layout of the project respectively

Figure 2 Satellite Image of Project Site

Plate 2 - Mudflat and Pollutants Figure 1 Project Location

Figure 3 – Layout Plan of Project

2 Solutions Identified and Implemented

The project’s vision is to rehabilitate the coastal zone and restore the beauty of the natural environment at Teluk Tekek.After rigorous study, investigation and detailed design including numerical modeling the following measures were identified and implemented -Rehabilitate the sandy beach along Teluk Tekek suitable for recreation

-Provide solution to overcome the beach pollution caused by polluted discharge into the river and sea

-Enhance the aesthetic of the beach zone incorporating landscape features

-Overcome river mouth siltation problem to allow free access for boats entering or exiting the river mouth

-Carry out river improvement works at Tekek river and Batang Sabut river

-Provide proper, safe and sheltered berthing and mooring facilities for tourist boat operators

Land form is narrow and steep and close to Marine Park centre where coral reefs are present In zone 1 approximately 600m long seafront promenade was created (Plate 3) A two tier seawall using a combination of retaining wall and Labuan Block was designed in

an optimum manner to achieve the following objectives :

- protect the coastline from erosion

- avoid impact to the coral reefs at the Marine Park Centre

- create an upper and a lower walkway to allow tourist to get near to the water

- reduce the reflection of waves to create a calmer sea condition at the Marine Park Centre

- reduce the overall structural dimensions and construction cost

- increase the recreational and aesthetic values of the seafront promenade

Figure 4 - Zone 1 Layout Plan

At the Marine Park Centre an elevated promenade platform of 5m width has been constructed along the beachfront to create a motorcycle track and parking space for the marine park visitors which has resolved the congestion problem at the area

2b Zone 2 (Sg Air Hantu to Existing Revetment)

Zone 2, approximately 600m long of beach was restored with imported sand from the mainland A 20 to 40 metre wide beach berm was designed to create a sandy beach to enhance its recreational value (Plate 4) The beach nourishment terminates at the groyne adjacent to the Sg Air Hantu river mouth

Figure 5 - Zone 2 Layout Plan Plate 4 - Zone 2 Restored Beach (Looking

toward Taman Laut)

Plate 3 - Two Tier Sea wall In Zone 1

2c Zone 3 (Sg Tekek river mouth to TNB Jetty)

The Tekek Jetty is located in this Zone Tourists arriving by sea will be presented with their first impression and experience upon setting foot on the island The length of shoreline is approximately 770m Many restaurants, stores and chalets are located along this stretch of beach

The beach was nourished with imported sand to provide a 30m berm The old precast flexslab was covered by the sand nourishment to create a sandy beach conducive for recreational purposes as illustrated in plate 5

Figure 6 - Zone 3 Layout Plan

A low crest groin (plate 6) was constructed

to prevent the beach sand in Zone 3 from

spreading into the Tekek river mouth The

groyne head was designed to control the

longshore sediments transport and also to

meet navigational clearance for ferry

berthing at Tekek jetty

Plate 6 – Groin in Zone 3

2d Zone 4 (Tg Said headland to Marina)

Zone 4 is isolated from the rest of the zones by the Marina The 740m beach is stabilized

by PEM-system to reduce the rate of beach erosion There are corals in this stretch of beach, no structural or reclamation works was proposed to avoid impact to the corals

Plate 5 - In Zone 3 approximately 700 m nourished beach covers up the Flex Slab.

Figure7 - Layout of Zone 4 Work

3 River Mouth Improvement Works

The river mouth of Tekek river was deepened to create a basin to improve navigation at Tekek river. Cascading granite rock revetment was used at the waterfront area of the Custom complex This is first time such design is used in Malaysia It is aesthetically pleasing and conducive for recreation, it allows close contact with the sea and reduces wave reflection in the basin at the river mouth as illustrated in Plate 7

The cascading structure is made from

cut granite blocks This type of block

revetment has been used in China and

Europe The cascading granite blocks

are arranged in a compact and intact

manner to allow the wave energy to be

transmitted and dissipated among the

blocks upon the wave breaking on the

granite block The cascade granite

block can perform all the functions

required of an effective revetment i.e

erosion protection, wave run-up

reduction, etc

Figure 8 - River Mouth Improvement works layout plan

Figure 9 - Cascaded Seawall Design Plate 7 -Cascaded Granite Block Revetment

4 Sg Tekek and Sg Sabut River Improvement Works:

Approximately 430m length of Tekek River and 140m length of Sabut River were deepened and lined with retaining walls The design of river improvement works was designed to achieve the following objectives :

- cater for the storm water flow to prevent flooding at Tekek area

- create space for boat mooring facility

- minimize acquisition of private lands

- provide space for recreational facilities , landscaping and drainage works

SECTION C

SECTION D

Figure10-River Improvement Works Plate 8 - Sg Tekek River Improvement

Works and Boat Mooring Facility

The river improvement works were complimented with hard and soft landscaping on both banks The river walkway is landscaped with steps to allow people to sit and enjoy the rustic scenery of Tekek and enjoy the sea view

The Project has also provided much needed safe navigation and boat mooring and berthing infrastructures (Plate 8) The boating facilities has the capacity to accommodate at least 102 nos of boats The berthing facility consists of a floating dock system and a dry dockage yard further upstream of the river The floating platform is constructed using polyethylene pontoons

The river improvement works involved the followings:

- Stabilizing the river banks against erosion and bank collapse

- Removal of contaminated sediment deposited at the riverbed

- Sewerage water be treated for primary treatment before discharging into the river

- Sullage water be collected and separated from the used water before it flows into - primary treatment system

- Providing boat access and mooring facilities at Sg Tekek

- Beautification of the rivers and the creation of landscaped river walk

The river improvement works were complimented with hard and soft landscaping on both banks The river walkway were landscaped with steps to allow people to sit and enjoy the rustic scenery

of Tekek and enjoy the sea view At strategic locations, steps were provided to allow people to walk into the river channels during low water

Figure 11-Layout of River Mouth Improvement Works at Sg Tekek and Sg Batang Sabut

The design of river improvement works and berthing facility has taken into consideration the results of boat inventory survey, wave action, currents, water level fluctuations, level of seasonal boat traffic, land availability, siltation deposition rates and anticipated frequencies

of dredging

5 Water Quality Study

A detailed water quality study was carried out at the main rivers discharging into the coastal water The study included sampling of water quality parameters at strategic locations, and the parameters were subsequently used in the water quality modelling The water quality study was carried out for the following purposes:

River Mouth Improvement Works -Riverbed Excavation

Vertical River Wall and Riverbed Deepening

Sg Tekek River Improvement Works

Sg Batang Sabut

Improvement Works

for the river and marine for pre-project and post project conditions

- To identify the sources of pollutants

while the water quality modelling determined the impacts before, during and after the construction stage

- To identify mitigation measures for

construction during the construction stages

environmental monitoring

Figure 12- Model Mesh

Using the established model, the design (beach nourishment, river mouth improvement, etc) were tested to assess their impact on the environmental As a result, beach nourishment at Zone 1 and Zone 4 was omitted to avoid impact to the coral reefs

Based on the water quality result, the design of the project, in particular, beach nourishment and seawall construction, was modified A double silt curtain system was adopted to control the spread of sediment plume during sand filling for the beach nourishment From the water quality study, it was apparent that the main sources of pollutant (BOD, TP, TN) that deteriorated overtimes were due to the sewerage water and oil and grease from boat servicing from the river trapped in the river mouth

6 Marine Biological Survey - Coral Reef Mapping and Diversity Assessment

The nearshore coral reef is vulnerable to the beach nourishment Therefore, marine biologists were engaged to carry a marine biological survey The scope of marine biological survey includes coral reef, fish, macroinvertebrates benthos, sea grass, plankton, etc Of these surveys, the coral reef mapping has a major impact of the civil engineering design A detailed investigation on the living status of the coral reef and their distribution and species was also identified as illustrated in plate 9

Plate 9 - Photos of Coral Reef Taken At Tekek Nearshore Coastal

In the context of engineering, the design of beach nourishment was modified based on the coral reef mapping, and confirmed by marine biologists

7 Hydraulic Modeling

A detailed numerical modeling using MIKE 21 Flexible Mesh Module was carried out The objectives of the numerical modeling are as follows:

(i) To analyze the existing coastal environment and historical evolution of coastal

beach

(ii) To assess the impact of the proposed coastal structures on the coastal environment, (iii) To determine the optimal solution that has the least negative environmental impact,

and potential mitigation measures

MIKE 21 FM Hydrodynamic Module (HD) has been employed to simulate the tidal hydraulics and MIKE 21 FM Spectral Wave (SW) to simulate wave attacking the shoreline The estimated extreme waves were simulated for 15dgn, 30dgn and 45dgn For storms coming from directions between 45dgn and 70dgn are sheltered by the island itself

8 Beach Nourishment Design

Beach nourishment is designed based on international guidelines, such as CUR (1986), Dean (2003), CEM (2003) and SPM (1984) Grab sampling of existing beach sediment and the potential sand sources from the adjacent river mouth has been carried out to confirm the compatibility of the sediment properties of the existing beach and the beach sand from the borrow site

The design requirements for the Beach Nourishment Works are as follows:

- To provide a suitable beach width, berm height and slope

- Adequate protection by waves and tides

- Fill material shall be marine sand with less than 10% fines content

- Fill material shall be coarser than the native sand material

- The Overfill Factor (RA) shall lie in the stable zone within Quadrant 3 and Quadrant 2 beneath the 1.02 Isolines as shown in CEM (2003)

- The Renourishment factor (RJ) shall lie in the stable zone with values of RJ not greater than 1.0 as shown in CEM (2003)

The berm elevation and width has been designed based on water level fluctuation (tides and storm surge), normal foreshore and nearshore slope, wave climates and sand fill properties The grain size for the nourish sand is defined as median grain size d50=0.44mm which is an approximately average of the grain size at the upper beach