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    LIST OF PHY

    HYDRAU

    National Hydraulic

    Ministry of

    ICAL MODELLING PROJE

    IC AND INSTRUMENTATI

    LABORATORY

    Research Institute of Malaysia (NAHRI

    Natural Resources & Environment (NRE

    www.nahrim.gov.my

    TS IN

    ON

    ))

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    LIST OF PYSICAL MODELLING PROJECTS IN HYDRAULIC AND

    INSTRUMENTATION LABORATORY

    NO. PHYSICAL MODELLING CLIENTCOST

    (RM) DATE

    1.

    STUDY ON SUITABILITY OF GEO TUBE TO

    ADDRESS EROSION PROBLEM FOR

    MANGROVE REPLANTING AT SG.HJ.

    DORANI, SELANGOR DARUL EHSAN

    FRIM 200,000 MAY 2010

    2.

    HYDRAULIC MODEL INVESTIGATION OF

    THE PROPOSED ALTERATION OF BATU DAM

    SPILLWAY, SELANGOR DARUL EHSAN

    PUNCAK

    NIAGA SDN

    BHD

    150,000 APRIL 2007

    3.

    STRUCTURAL STABILITY OF ROCK

    ARMOUR AS GROYNE FOR BATU MANIKAR

    BEACHES, FEDERAL TERITORY OF LABUAN

    PERBADANAN

    LABUAN50,000 JUNE 2010

    4.

    FLOOD MEDELLING EVALUATION IN RIVER

    MEANDERING CHANNEL UNDER TIDAL

    EFFECT FOR SUNGAI SELANGOR

    IN HOUSE 100,000 JULY 2008

    5.

    STRUCTURE STABILLITY TESTING FOR

    ARMOUR ROCK REVETMENT DESIGN AT

    TANJUNG PIAI, JOHOR DARUL TAZIM

    IN HOUSE 20,000MARCH

    2010

    6.

    STUDY OF WABCORE ARTIFICIAL REEF

    STABILITY FOR BREAKWATERIN HOUSE 50,000

    AUGUST

    2010

    7.THE DEVELOPMENT OG H-BLOCK FORRIVER BANK PROTECTION

    IN HOUSE 30,000 JANUARY2010

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    1

    PHYSICAL MODELING 1: STUDY ON SUITABILITY OF GEO-TUBE TO ADDRESS

    EROSION PROBLEM FOR MANGROVE REPLANTING AT SG. HJ. DORANI

    1. Background

    Sg. Hj. Dorani (Figure 1) which is located near Sabak Bernam area is one of the selected location for

    mangrove replanting program after the December 2004 Tsunami event in Malaysia. To increase the

    potential of survival rate of replanted mangrove, Department of Irrigation and Drainage (DID) has

    installed a geo-tube in front of the replanting area to break the incoming wave before it hit the coastal

    shoreline and the mangrove replanting area. Physical modeling was proposed to evaluate the potential

    deposition of sedimentation at the site. In addition, physical model served as a tool to evaluate complex

    coastal phenomenon that are not sufficiently address by numerical models.

    Figure 1: Study Area

    Sg. Hj. Dorani coastline area is very diverse and exposed to prominent coastal physical parameter such as

    tide, wave and current impact, and is dominantly influenced by tidal fluctuation. In house marine data

    collection exercise by NAHRIM revealed that the bathymetry condition at the study area is quite gentle.

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    Following this, NAHRIM has developed a physical model to provide better understanding of the coastline

    responds due to wave action. A cohesive bed model was constructed at NAHRIMs Hydraulic and

    Instrumentation Laboratory using 2D wave basin with a scale of 1: 20.

    2. Objectives

    The main objective of the study can be described as follows:

    i. To evaluate the possible cause of ongoing erosion problem at Sg. Hj. Dorani shoreline.ii. To analyze the sedimentation pattern at existing Geo-tube installation area and the erosion rate at

    Sungai Haji Dorani shoreline.

    iii. To propose suitable counter measure for the positioning of geo-tube for mangrove replanting.

    3. Methodology

    Sungai Hj Dorani model was constructed with the size of 26 m x 24 m, which represent an area of 350 mx 520 m on site, as shown in Figure 2 below.

    Figure 2: Model Design for Physical Test

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    The work flow of the physical model is as shown in Figure 3.

    Figure 3: Sungai Hj Dorani physical modeling work flow

    Model Scaling

    Model Construction

    Instrument Calibration

    First option testing (144 hours)

    Measurement & Analysis

    Model Reconstruct

    Second option testing (144 hours)

    Measurement & Analysis

    Result comparison

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    Table 1 below shows the calculated scaled parameters that were tested for the particular model.

    Table 1: Sg. Hj. Dorani Scaled Parameter

    The test was carried out for 144 hours, which is equivalent to 32 days in nature. Bed level profile wasmeasured after 72 hours. Bed profile changes showed some significant sediment movement pattern along

    the test period.

    4. Results

    Sungai Hj Dorani coastline bathymetry area was measured to be less than 1 meter during the low tide

    condition. The coastal water is withdrawn from near shore area about 2 km and the geo-tube area wasexposed throughout that period (Figure 3). Waves that present at Sg. Hj. Dorani area was also one of the

    major factor that contributes to erosion and deposition surrounding the geo-tube area. Sungai Hj Dorani

    coastline is also facing occurrence of breaking type of wave due to gentle water depth changes at the

    study area.

    When the depth of water is less than half the wavelength, waves begin to interact with the bottom area

    and become shallow water waves. As the depth decreases the waves slow up and steepen. At water depth

    SG. HJ. DORANI. PHYSICAL MODEL

    Geometric Scale, Lr 20

    Then Velocity scale and Time scale 4.5

    Parameter Prototype Model Scale

    Breakwater Length, (m) 200.00 10.0

    Breakwater Height, (m) 4.50 0.225

    Breakwater Width, (m) 3.50 0.175

    Average Current Velocity (m/s) 0.15 0.034

    Design Wave Height, Hda (m) 0.36 0.018

    Design Wave Height, Hmax (m) 0.57 0.0285

    Wave Period (s)m, ave of Ave (3-5) 4.60 1.2

    Tidal Range Max (m) 4.20 0.21

    Tidal Range Min (m) 1.50 0.075

    Tidal Range Ave (m) 2.30 0.115

    Tidal Range (m), Design 2.30 0.115

    Beach Material size (Silt)(mm) 0.05 0.0025Falling Velocity ( cm/s) 0.72 0.036

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    of 1.3 times the wave height is reduced and the particles of water in the crest have no room to completetheir cycles. At this point the wave breaks, and moves out of the wave generation area so that the wave

    period is conserved. This is an important observation since it enables us to predict when waves will begin

    to act as shallow-water waves.

    This phenomenon induces wave refraction at the geo-tube area and straight to the shoreline. The current

    wave condition in the deeper water area caused critical erosion at southern part of the geo-tube area.

    Figure 3: Condition in basin after the first Test

    Figure 4: Erosion and Deposition of Model Area

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    5. Conclusion

    Counter measures needs to be taken to minimize the erosion factor. As best solution option, the geo-tube

    was suggested to be placed at distance of 120m 150m from the shoreline area. This will allow the

    incoming waves to be refracted with allowable space before they hit the coastline. This option also

    increases level of sedimentation behind the geo- tube area, thus provide buffer area to protect themangrove replanting site.

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    1

    PHYSICAL MODELING 2: HYDRAULIC MODEL INVESTIGATIONS OF THE

    PROPOSED ALTERATION OF BATU DAM SPILLWAY, SELANGOR DARUL EHSAN

    1. Background

    NAHRIM have carried out a physical modelling for study the efficiency of the new proposed

    spillway at Batu Dam. This is part of the Scheme No. 3: Transfer of Raw Water from Batu Pondand Pumped Storage at Batu Dam which is proposed to mitigate expected water deficit in

    Selangor and Kuala Lumpur.

    Apart from raw water pipeline, pump station and upgrading of treatment plant, the scheme will

    also include the raising of Batu Dam. One of the components of work is the modification at the

    existing spillway. The proposed hydraulic model study will aim to evaluate the hydraulic

    performance of the modified spillway.

    Batu Dam is a 39m high zoned, earth-rock filled dam. Existing dam crest is at elevation 109.5mand it is proposed to raise the dam crest level to 110m. Existing spillway is located on the leftabutment. It has a side channel inlet structure with a 23m long crest at elevation 104.85m. The

    chute is 145m long and ends with a 32.5m long stilling basin at invert level of 60m. A raw inlet

    structure with overflow weir will be constructed ahead of the existing spillway. Overflow level isset at elevation of 106.7m. The design requirement is to ensure the integrity of the dam and

    spillway is still intact under design Probable Maximum Flood (PMF) scenario.

    2. Objectives

    The main objective of the study is (i) to construct a physical model of the Batu Dam spillway,(ii) to investigate hydraulic behaviour of the spillway and also its ancillary structures under a

    range of design discharges, and, (iii) to investigate the discharge capacity of the prototype meets

    the design requirement and measures the hydraulic parameters in order to judge whether thedesign is feasible.

    3. Scope of Study

    The following scope of work is needed to make an appraisal of the capacity and erosion aspects

    of the dam and the overall performance of the spillway as well as to make informedrecommendations of its hydraulic performance and proposed alterations.

    i. Investigation of the spillway discharge capacity with respect to various reservoir levelsand the model discharge coefficient as well as requirement for flood release.

    ii. To study the flow pattern and flow surface profile on the dam and in the bottom outlet fordifferent cases.

    iii. Velocity and pressure measurements at all relevant points for different flow conditions.

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    iv. Determination of the intensity of turbulence at different points on the weir, transitionalarea, chute and energy dissipater.

    v. Energy dissipation and scouring study to assess the suitability of downstream bed andbank protection.

    vi. Stage discharge curve for the spillway model.The model scale was set at 1:25 ratio and then tested under designed Probable Maximum Flood

    (PMF) scenario up to 300 m3 /s (96 l/s in the test model). Water supply was provided by five

    pumps with a maximum capacity of 16.7 l/s each and one pump with a maximum capacity of 50

    l/s.

    4. Methodology

    i) The main thrust of the study primarily consists of physical modeling work. A scaled model of thespillway and all its ancillaries will be constructed.

    ii) Upon construction of the model, trial tests will be conducted to determine its functionality.iii) Experimental works proceeds as soon as calibration results are satisfactory.iv) Subsequently data will be compiled data, process and analyze to simulate the actual (model) and

    predicted (prototype) conditions of the spillway.

    v) Simulations with respect to various reservoir levels and discharges to investigate effects of thevaried flow conditions will also be performed.

    vi) Finally, detailed appraisal of the model results will be provided in order to evaluate overallperformance of the proposed spillway, and to suggest possible maintenance and improvement

    techniques or alterations where required.

    5. Results

    The incoming flow is steady as it has been stabilized before reaching the inlet opening. Each change ofdischarge rate will require about 5-10 minutes for the water to stabilize (Refer to Figure 1).

    Figure 1: Intake/Approach Channel

    From test for the discharge of 96 l/s (prototype: 300 m3/s), it was observed that no freeboard was visible.

    In fact the water sometimes overflows the transition portion (Refer to Figure 2).

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    Figure 2: Transition Portion

    Starting from discharge of 80 l/s (prototype: 250 m3/s), the water in the chute started to overflow

    occasionally. At a discharge of 96 l/s (prototype: 300 m3/s), there was permanent overflow at the middle

    section along the spillway chute (Refer to Figure 3).

    Figure 3: Spillway Chute

    From test showed that water already reached the existing ground level for discharge of 32 l/s

    (prototype: 100 m3/s). The water went above the existing ground level if the discharge is greater

    (Refer to Figure 4).

    Figure 4: Stilling Basin

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    6. Conclusion

    From the tests performed, the transition portion and the spillway chute is adequate for the

    original design discharge but the stilling basin (energy dissipater) is inadequate to cater for the

    high discharge in the original design. The proposed overflow weir is not found to have anybenefit in terms of controlling high flows (prototype: 200 m3/s, model: 64 l/s) as there are no

    difference in the results when compared to test conditions without the overflow weir installed.Therefore to cater for a discharge of up to 300 m3/s, it is recommended that the freeboard at the

    existing transition portion be increased by at least 3m and the wall of the spillway chute at the

    middle be increased by 2m. For the stilling basin, its recommended that bunds of 5m high beconstructed around the perimeter to prevent inundation of the surrounding grounds.

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    1

    PHYSICAL MODELING 3: STRUCTURAL STABILITY OF ROCK ARMOUR AS GROYNE

    FOR BATU MANIKAR BEACHES, FEDERAL TERITORY OF LABUAN

    1. Background

    The project is known as Proposed Beach Erosion Mitigation Structures and Beach Nourishment Project

    at Batu Manikar Beach, Labuan. The structure testing was design to investigate the stability of thestructure before the construction phase begins at the actual site.

    Batu Manikar beach, situated at the west coast of Labuan Island is constantly exposed to the effects of sea

    and swells emanating from the South China Sea. Over the years, the beach stretch has shown signs of

    erosion; with the beach frontage area observed to slowly retreating to the adjacent coastal road network.The main focus of the coastal protection and beach nourishment project is to mitigate the ongoing coastal

    erosion thus prevent damage and loss of the existing coastal areas.

    2. Objectives

    The objective of the study are summarize below:

    i. To evaluate the stability of the proposed structure under various design parameter;ii. To assess the suitability of armour rock in the proposed design;

    iii. To assess the scouring impact around the structure.3. Scope of Study

    There are 3 units of 200m length groyne having a spacing of 730m and 810m from north to south

    respectively, to be constructed along the Batu Manikar beach. The groyne are made up of two layers of

    rock armour, namely primary and secondary layers which will be placed over the core material with a

    layer of geotextile as the under layer. The primary layer is made up of 1,400 2,400kg granite with more

    than 50% comprised of 1,900kg armour, while the secondary layer is made up of 120kg -190kg granite.

    The 200m length of groyne will be constructed and extended into the sea at the right angle to shoreline.The designed crest level is +2.2m MSL with side slopes of 1:2 and 1:3 for the trunk sections and head

    sections respectively.

    The cross-sectional profile of the tested groyne is shown in Figure 1..

    Figure 1: Groyne cross section for the testing

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    4. Methodology

    The model was constructed in the wave flume. The construction started with the marking of cross

    sectional profile on the flumes glass panel (Figure 2a). The marking includes the height and width of the

    structure for each layer. The tested water level was also marked on the glass panel to ensure accuratewater level throughout the tests. Afterwards, the structure layers were constructed using the selected

    gravel size (Figure 2b).

    After the construction stage, testings for the structure were be run according to the parameters shown in

    Table 1 below:

    Table 1: Tested design parameters

    Figure 2a: Marking process Figure 2b: Structure to be tested

    Test 01 Test 02 Test 03 Test 04

    Model Scale 1:10 1:10 1:10 1:10

    Water Depth (m) 0.74 - (normal) 0.8 - (extreme) 0.8 - (extreme) 0.8 - (extreme)

    Wave Height Max - Measured 1.685cm 1.702cm 1.701cm 1.705cm

    Groyne Structure Weight

    - First Layer 1.4kg - 2.4kg (with 50% more than 1.9kg) 1.4kg - 2.4kg (with 50% more than 1.9kg) 1.2kg - 2.0kg (with 50% more than 1.6kg) 1.2kg - 1.6kg (with 50% more than 1.4kg)

    - Second Layer 120g-190g (without Geotextiles) 120g-190g (Geotextiles) 120g-190g (Geotextiles) 120g-190g (Geotextiles)

    Test Duration 12 Hours 12 Hours 12 Hours 12 Hours

    Data Set on Wave Generater

    - Water Depth (m) : 0.74 0.8 0.8 0.8

    - Wave Height (m) : 0.3 0.3 0.3 0.3

    - Wave Period (s) : 3 3.2 3.2 3.2

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    5. Results

    The overall test results are tabulated in Table 2 and Figure 3 below.

    Table 2: Tested parameter and observation

    Model Scale 1:10

    Water Depth (m) 0.8 - (extreme)

    Wave Height Max - Measured 1.705 cm

    Test Duration 12 Hours

    Groyne Structure Weight

    - First Layer

    1.2kg 1.6kg (with 50% comprised of more than

    1.4kg)

    - Second Layer 120g-190g (with Geo-textiles)

    Data Set

    - Water Depth (m) : 0.8

    - Wave Height (m) : 0.3

    - Wave Period (s) : 3.2

    Observation: After testing

    No movement for the 1st

    layer stone

    Critical movement in the front section, almost 80 % of stone moved to the back section

    Sand in front of the structure was 25 % scattered to the back section, showeing high

    potential of erosion

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    20 cm

    20 cm

    30 cm

    18cm

    18cm

    30 cm

    18 cm

    38 cm

    15 cm

    Figure 3: Structure and sediment movement summary (extreme condition)

    Before Test:

    1.4kg-2.4kg,

    no color

    After Test:

    1.4kg-2.4kg, no

    color 120g-190g, Green =

    Before Test:

    1.4kg-2.4kg,

    no color

    After Test:

    1.4kg-2.4kg, no

    color

    120 -190

    After Test:

    1.4kg-2.4kg,

    yellow

    120 -190

    Before Test:

    1.4kg-2.4kg,

    yellow

    Before Test:

    1.4kg-2.4kg,yellow

    After Test:

    1.4kg-2.4kg,yellow

    120 -190

    Before Test:

    1.4kg-2.4kg,

    yellow

    After Test:

    1.4kg-2.4kg,

    yellow

    120 -190

    Before Test:

    120g-190g,

    Red-

    Bottom=137 c

    After Test:

    120g-190g,

    Green=102 Blue

    = 9 cs

    After Test:120g-190g,

    Green=3pcs

    Blue = 17 cs

    Before Test:120g-190g,

    Red-

    Bottom=83 cs

    Before Test:

    Sand

    After Test:

    120g-190g,

    Green =7pcs

    Blue = 15pcs,

    After Test:

    120g-190g,

    Blue = 1pcs,

    Before Test:

    Sand

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    6. Conclusion

    The proposed model structure seems to be stable under normal test condition. Nevertheless, a large

    amount of armour rocks were displaced when the model was tested under extreme test condition,

    particularly in the middle section and near the front toe area. It is therefore proposed that a larger armourrock size be used for the middle section and toe area of the proposed groyne structure to enhanced the

    overall stability.

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    PHYSICAL MODELING 4: FLOOD MODELLING EVALUATION IN RIVER

    MEANDERING CHANNEL UNDER TIDAL EFFECT FOR SUNGAI SELANGOR

    1. Background

    Basically flood can occur at any reach of a river due to different factors. In the upstream area it usually

    caused by the discharge which exceed bankfull flow and that discharge cannot be sustained by rivercross section and river bed. Whereas flood occur in estuary area is caused by the tidal influences.

    However, at the middle stretch of the open channel the occurence of flood is more complex to explainbecause of the combination of both factors.

    Presently there are still lack of research on open channel hydraulics which is under the tidalinfluenced. One of the main reasons to the lack of research in this area is the limited data available

    such as water level and flow along the river bed. The difficulty to produce rating curve in the tidal

    influence area also influence the calibration process. Therefore, only one value is normally used inhydraulic analysis, such as highest spring tide which will result in very high water level and is

    inaccurate.

    2. Objectives

    The objective of the study can be describe as follows:

    i. To reduce flooding problem along the river by introducing cut off at the downstream.ii. To assess the floodplain and water level for various flow conditions and tidal influence

    3. Scope of Study

    i. To construct physical model at National Hydraulic Research Institute of Malaysia. Thisincludes choice of materials, physical model scale, evaluating and setting up the instruments.

    ii.

    Gathering the available data of Sungai Selangor for the simulation in the experiment. Runningthe physical experiment covering flow from low to high without tidal influence under low

    tide, mean sea level and high tide and flows with tidal effect. Figure 1 shows the Flowchart ofthe study process

    Figure 1: Flow Chart of the Study Process

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    4. Methodology

    Physical model which was developed covering the tidal influences area. The non distorted scale of1:100 was used in the physical model after considering the practicality of the size in term of spaceavailable, construction cost and time required for the construction.

    The overall size of physical model is 10m x 40m and with a scale of 1:100. Figure 2 shows schematic

    diagram of the model and Figure 3 shows the overall view of the constructed model.

    Figure 2: Schematic diagram of physical model

    Figure 3: Overall view of physical model from upstream

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    Simulation process was carried out and the result of each experiments was recorded. The experimentswas done under different scenarios, at different flow rates and tides conditions where the readings was

    recorded at eight (8) stations in the physical model as shown in the Figure 2. Cases of simulationscarried out are shown in Table 1.

    Table 1: Test Cases

    Case no Tide condition Flow (l/s)

    1 Without tidal effect 1 , 2, 3, 4, 5, 6, 7, 8

    2 With tidal effect 1 , 2, 3, 4, 5, 6, 7, 8

    3 With tidal effect & cut off 1 , 2, 3, 4, 5, 6, 7, 8

    5. Results

    The experiment were carried out for various scenarios as describe above. The data of water level and

    velocity for each experiment were recorded at eight (8) identified stations with eight different values

    of flows. At each location three (3) readings were taken for velocity i.e at the middle and two sides ofthe channel and one (1) reading for water level i.e at the middle of the channel. Flow and velocity

    were taken for three (3) different water levels (fixed) at the downstream i.e low water, mean sea and

    high water. For the tidal effect one reading for water level and velocity were taken. These levels are

    based on the tide data taken at the refered locations. Outcome of the analysis obtain from physicalmodeling were analyse.

    Figure 4 shows the extend of the flooded area, for the original layout the experiment shows the water

    start to overflow the bank when flow is 2l/s and flooded when flow is 3l/s and worsen when the flowincreases. As for the cut off section the experiment shows the water start to overflow the bank when

    flow is 3l/s and flooded when flow is 4l/s and worsen when the flow increases.

    Figure 4: Flood Plain - Comparison on observed flooded area without cut off and with cut off

    under tidal effect for 5 l/s flow

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    Figure 5 and 6 shows the plot ofwater level increases as the flow inc

    Figure 5: Plot of water level vs fl

    Figure 6: Plot of water level vs fl

    6. Conclusion

    The analysis shows that the water

    velocity was inconsistent and fluctuit also shows that the cut off may a

    not totally solved it. The experimunder all tested conditions.

    ater level versus flow for 5 l/s discharge. As shoreases for both without and with cut off.

    w under tidal effect for all station taken in flood

    cut off

    w under tidal effect for all station taken in floodoff

    level increases as the flow increases and causes

    ates and does not directly dependent on flow. Fromble to help alleviate the flood problems to certain

    ent also shows that the flood does not occurs at t

    Station A

    Station B

    Station C

    Station D

    Station E

    Station F

    Station H

    Station G

    4

    wn below that

    plain without

    plain with cut

    the flood. The

    the experimentxtent but does

    e downstream

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    PHYSICAL MODELING 5: STRUCTURE STABILITY TESTING FOR ARMOUR

    ROCK REVETMENT DESIGN AT TANJUNG PIAI, JOHOR DARUL TAZIM

    1. Background

    The study site is a mangrove swamp of 1.8 km long that forms part of a pocket beach in the

    southern tip of Peninsular Malaysia. Recently, as the hinterland of the Sg Pulai is beingdeveloped into various water resources schemes, and the construction of port facilities for

    deep draft vessels is being implemented, the coastline at the surrounding the studyt site is

    observed to be eroding at a high rate. Mangroves are falling due to the erosion of the soil

    underneath them. The likely cause of the bank erosion is the reduced sediment supply fromthe hinterland and the dredging of ship transportation channel that divert the course of

    sediment supply to the mud flat of the project site. A re-adjustment of the coastline has beeninitiated, with the tendency of beaches along this hook-shaped bay receding inland.

    Rock revetment and soft rock are two systems of coastal protection suggested to address this

    coastline development phenomenon. They protect the beach from further erosion andsafeguard the mangrove in the State Park and prevent intrusion of seawater into the

    agriculture land established behind existing coastal bunds. Where erosion is serious and hasremoved entire mangroves that form the first line of defence for the beach, stone revetment is

    incorporated to contain the wave attack and break-up the wave energy within the revetment.Where the coastline is still sheltered by mangrove trees, soft rock is used to line the fringe of

    mangrove forest and to reinforce the morphology of the coast.

    2. Objectives

    The main objective of the study can be described as follows:

    1. To assess the stability of the design structure with a various condition.2. To indentify the adverse impact of the seabed around the structure.

    3. Scope of Study

    i. Preliminary assessment by extracting information from reports related to the studyarea.

    ii. Data collection & hydro graphic survey to ensure the similarity between model andprototype.

    iii. Layout plan of the scaled model in the flume for each cases test.iv. Preparation of flume and material depending on the layout plan and cases designv. Wave calibration to get the scaled design wave height.

    vi. Model construction at the design wave height location.vii. Structure testing by running the scaled design wave height and period for certain

    duration depending on the cases; and setup the observation point for analysis

    purposes.

    viii. Analysis processes using a video/camera to observe the model (stone revetment)movement before and after each test.

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    4. Methodology

    The model scale was set at 1:7 ratios and then tested under 20 ARI and 100 ARI conditions,as shown in Table 1 below.

    Table 1: Test parameter for revetment model

    Prototype Model

    Duration 3 day 27.2 hour

    20 ARI wave 1 m 14.3 cm

    100 ARI wave 2 m 28.6 cm

    Wave period 3.6 s 1.4 s

    MSL 0.373 m 5.3 cm

    MHWS (20 ARI water level) 1.628 m 23.3 cm

    HAT (100 ARI water level) 2.408 m 34.4 cm

    Armour layer rock 200 kg (min) 0.58 kg (min)

    450 kg (max) 1.31 kg (max)

    Under layer rock 30 kg (min) 0.09 kg (min)

    150 kg (max) 0.44 kg (max)

    A method that is commonly used for quantifying damage in rubble-mound structure models is

    by counting the number of individual armour units that have been dislodged. The movementcan be observed and noted, or more conveniently, video and photographic documentation can

    be used to record test results. The method to describe the damage percentage is the use of theNd. Hudson (1959) defined damage as the percentage of dislodged armour units to the total

    number of armour units:

    Where:Ndisplaced = number of displaced stoneNTotal = total number of stones in that layer (section)

    The damage is typically calculated for individual section. Typically displaced stones arestones which are displaced by more than one unit diameter (Dn50). Armour is considered a

    failure when theNdis more than 10% damage.

    Wave overtopping is usually assessed by collecting the overtopping water in overtopping

    trays or tanks and measuring the overtopped water volume or mass. The number ofovertopping events can be assessed by a wave gauge at the crest of the breakwater or by

    continuous water level measurements (volume or mass) within the overtopping tray or tank.

    5. Results

    The results were tabulated in Figure 1 and Figure 2 below.

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    Before After

    Small movement but not significantly for the 1st

    stone layer. Its showedthe structure was stable with appropriate stone weight.

    2nd

    layer are stabilized by using the geo-textile as a basic layer by wrapped

    this layer. No movements because of the geo-textile tend to hold the stonewithin it.

    The overtopping seems not happen under this current water condition.

    Figure 1: Test result for 20 ARI wave scenarios

    Before After

    It was found the 1st

    layer rock were moved significantly especially at thefront slope of the structure after the increment 100% of the wave height and

    32 % of water level. The damage percentage = 7.12%

    2nd

    layer remain stable as previous test.

    The overtopping was occurred for this case. The height structure seems notsignificant to protect the shoreline during a certain period of time.

    The overtopping rate= 1.856 l/m/s

    Figure 2: Test result for 100 ARI wave scenarios

    6. Conclusion

    The current revetment design is capable of protecting the shoreline area up to 100 ARI wave

    condition. Even though there was some movement of the armour rocks, the amount did not

    exceed the 10% damage percentage limit, which was the set damage threshold.

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    1

    PHYSICAL MODELLING 6: STUDY OF WABCORE ARTIFICIAL REEF STABILITY FOR

    WAVE BREAKER FUNCTION

    1. Background

    In recent years, artificial reefs have become an increasingly attractive alternative for coastal

    protection. Artificial reefs can be used to protect or restore beaches and at the same time create anenvironment conducive for the growth of marine life. The WABCORE (refer to Figure 1), a

    composite system of concrete units developed by NAHRIMs researcher, is one such product

    designed for this dual purpose and provides an alternative to the use of rocks as construction material.

    The WABCORE units can be configured into several coastal and bank protection systems such as

    groynes, wave breakers and retaining walls. The first WABCORE structures in the form of stackingartificial reefs were deployed near Teluk Panuba, Pulau Tioman, Pahang in September 2005.

    Following this successful application of WABCORE units as a coral host, the WABCORE was

    further tested for its function as wave breaker with the purpose of creating a calm foreshore

    environment for another section of a beach. This configuration of WABCORE as wave breakers arealso intended to help build up a section of the beach to reduce erosion.

    Figure 1: The WABCORE Artificial Reef

    2. Objectives

    The objective of the study is to (i) verify the stability of the WABCORE as potential wave breaker,

    and (ii) to evaluate needs for improvement and optimization of the proposed WABCORE design aswave breakers.

    3. Scope of Study

    The scope of study is as follows:

    i. Examine the stability of wave breaker cross sectionsii. Measure the wave height at different position of the section area;

    iii. Asses the displacement of WABCORE units before and after each testsiv. Visual observations for scour evaluation and sediment accumulation capabilities of the

    structure

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    4. Methodology

    The models of WABCORE wave breaker were constructed at a scale of 1:2. The blocks are 0.25m inheight per block, and made of concrete with void areas to allow for permeability. The water depth

    will be designed at approximately -0.75m, allowing 0.25m crest between top of structure to thecorresponding designed water level. The rows of WABCORE blocks was placed with a distance of

    approximately 1mm in the model in order to ensure that the rows do not provide unrealistic support

    for each other.

    The incoming waves were determined by means of wave gauges positioned in a way allowing for

    separation of the incoming and reflected wave conditions. Additional wave gauges were positioned

    close to and behind the structure. The test program includes two different heights of a WABCOREprofile. A 1-layer and a 2-layer structure were studied, modeling a coastal protection profile and a

    wave breaker profile at shallow water. Maximum wave height of 0.5m and wave period of 5 secondswas generated. Each test was run equivalent to 5 hours in nature.

    For the majority of the tests the seabed in front of the structure was made as a fixed bed not allowing

    for scour. This is to avoid the model structure to fail because of scour before the stability can bestudied. However, a test series was included, where qualitative assessments of the scour risk will be

    made by performing tests with a sand bed in front of the structure. It should be stressed that damage tothe structure related to geotechnical settlements or to structural strength of the individual unit were not

    modeled in this study. A layer of modeled geotextile mat was laid to help assessment of theanticipated sand trapping capabilities of the model.

    The test program includes three test series:a. Test series 1: Tests with the one layer structure. Fixed bed in front of the structure.b. Test series 2: Tests with the two layer structure. Fixed bed in front of the structure.c. Test series 3: Tests with the one layer structure. Moveable (sand) bed in front of the structure.

    Figure 2: Testing of WABCORE stability in progress

    5. Results

    Initial results showed that WABCORE artificial reef proved to be stable during all the tests.

    WABCORE was able to reduce the significant wave height thereafter to about 30%. Displacementand movement of some of the WABCORE units were observed by photos taken before and after eachtest, most notably at the left and right section of the alignment. These movements was possibly

    enhanced by reflected wave action from the wave guide located at both side of the basin, as nosignificant movement occurred in the middle section (Refer to Figure 3a and 3b).

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    Figure 3a: 2 layer WABCORE before testing Figure 3b: 2 layer WABCORE after testing

    Visual observation and photos evaluation also showed only minor scour and possible degradation of

    the sand layer in front of the structure during test series 3. Interestingly, the WABCORE wasobserved to accumulate substantial amount of sediment into its inner part (Refer to Figure 4). This

    may be greatly influenced by the incorporation of voids in the WABCORE design.

    Figure 4: Side view showing sediment accumulation along the whole stretch of WABCORE

    wave breaker alignment

    The observed uplift forces were not great enough to topple the structure in both 1-layer and 2-layer

    tests, and so they remained stable throughout testing. It was also observed that without reinforcement

    the possibility of stress and fatigue cracks on WABCORE would be likely, therefore it wasrecommended that reinforcement be retained in the prototype.

    6. Conclusion

    WABCORE artificial reef has demonstrated initial stability element required topotentiallyfunction asa wave breaker. It is recommended that a detailed study of wave transmissions and overtopping flux

    be carried out in the wave flume to further assess the overall performance of the WABCORE. The

    capability of WABCORE to trap sediment may prove advantageous in self-consolidating the structure

    in the long run. Subsequently, the effect and possibility of varying the size of WABCORE voiddiameter and/or position to achieve optimum design efficiency as a wave breaker needs to be

    evaluated further.

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    1

    PHYSICAL MODELING 7: THE DEVELOPMENT OF H-BLOCK FOR RIVER BANK

    PROTECTION

    1. Background

    River serves as an important source of water and supports livelihoods. River is also essential fortransportation, acts as a defensive barrier, source for hydropower and recreational activities. However,

    rapid development involving indiscriminate clearing of land has caused increase in river discharges

    resulting in river bed scouring and bank erosion. This phenomenon has lead to river bank failures,

    contributing to large amount of sediments into the river, loss of land and degradation of river waterquality.

    One of the solutions to control the erosion and sedimentation problem is by protecting the river bank

    using products such as H-Block. The development of H-Block is undertaken by the Research Centre

    for River Management, National Hydraulic Research Institute of Malaysia (NAHRIM).

    2. Objectives

    i. To invent an innovative product for river bank protectionii. To spearhead the invention of water resources related products through long term R&D

    efforts

    3. Methodology

    The development of H-Block involved three phases namely, the design stage, the physical modeling

    and field tests. Once the design has been accepted, physical modeling with a series of tests andmeasurements follows. The physical modeling works are being carried out in the Hydraulic and

    Instrumentation Laboratory of NAHRIM which provides sufficient facilities and equipment for these

    purposes.

    The tested physical model parameters:

    Model Scale 1:10

    River Width 2 metersMaximum River Depth 0.5 meters

    Maximum River Flow 100 liters/second (l/s)River Sand Size 100 micron

    A series of physical model testing was carried out to test the performance of the product, some ofwhich are as follows:

    a. Test run for hydraulic channel without H-Block with flows of 80l/s, 30l/s and 15l/s for 24hours until bank failure. Bank slope is set at 1:1.

    b. Test run for hydraulic channel with H-Block without lock system for flows of 15l/s and 30l/sfor 24 hours until bank failure. Bank slope is set at 1:1 and 1:2.

    c. Test run for hydraulic channel with H-Block and lock system for flows of 15l/s and 30l/s for24 hours until bank failure. Bank slope is set at 1:1 and 1:2.

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    Figure 1: H Blok model construction ready for testing

    4. Results

    Result of the test run is summarized in Table 1 below.

    Table 1: Summary of tested flow parameter

    Measurement Low Flow High Flow Flow Difference

    Point Test 1 Test 2 Test 3 Test 1 Test 2 Test 3 High Flow Low Flow

    1 0.125 0.109 0.125 0.265 0.093 0.245 26% 12%

    2 0.127 0.109 0.127 0.247 0.225 0.242 24% 13%

    3 0.129 0.074 0.129 0.247 0.219 0.171 24% 13%

    4 0.130 0.111 0.129 0.233 0.219 0.252 23% 13%

    5 0.129 0.123 0.130 0.266 0.236 0.260 26% 13%

    6 0.125 0.119 0.130 0.250 0.207 0.255 25% 12%

    7 0.120 0.107 0.123 0.256 0.234 0.259 25% 12%8 0.118 0.117 0.123 0.232 0.237 0.292 23% 12%

    9 0.121 0.117 0.125 0.241 0.242 0.264 24% 12%

    The H Blok was observed to be successful in reducing the velocity of flow when constructed

    at the river bank model (refer Figure 2). This may due to the unique element of the structure

    itself which provide extra roughness element and also voids for permeability allowance.

    During testing for high flow conditions, movement of H Blok was detected at the river

    meandering section, whereas at the straight section H Blok was observed to be stable.

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    Figure 2 : Flow velocity before and after H Blok instalation

    5. Conclusion

    H Blok was considered successful in reducing the velocity of flow. The stability of H Blok

    very much depends on the river morphology e.g. width, shape, geotechnical aspect, and bank

    slope selection, with 1:1 slope giving a more favorable result. The joint spacing of the H Blok

    during construction needs to be considered carefully due to possibility of failure during high

    flows, particularly at the meandering section. The possibility of incorporating an interlocking

    feature for installation of H Blok at this critical river section needs to be studied further.

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    Other physical modeling studies conducted:

    1. Study On Local Scour at Complex Pier in 2D Flume (University Putra Malaysia - December2008)

    2. Study on General Sand Dispersion Pattern in Coastal Basin (June 2008)

    3. Breakwater Study On Muddy Coast For Mangrove Replanting in Parit Hj Dorani, Sabak Bernam,Selangor Part 1 & Part 2 (FRIM & JPSM - May 2010)

    4. Structure Stability Test for Semi-Swath Boat Model Fasa 1 in 2D Flume (UiTM - July 2010)

    5. Analysis of Dry Sieving on Sediment Distribution Pattern for Pangkor Island (Pusat HidrografiNasional - July 2010)

    6. Experiment on Sediment Settling Velocity for Muddy Coast of Sungai Haji Dorani (March 2010)

    7. Experiment on Sediment Settling Velocity for Fresh Water of Sungai Kuyoh (March 2010)

    8.

    Structure Stability Test for Revetment in Johor State in 2D Flume (March 2010)

    9. Study of Rainwater Harvesting System First Flush Effect (August 2010)

    10.Evaluation of the Laboratory Performance of Field Offtake 150mm Diameter with Flexi-Gatesand Float Type Automated Flow Control Valve and Flat Regulator for Flow Control and

    Measurement in Tertiary Irrigation (University Putra Malaysia) *

    11. Study of Lift and Drag Balance With Models : Characteristics of Flow Around Two VaryingDiameter Cylinders and an Aerofoil (Multimedia University)*

    12.Physical Modelling Study of Terengganu Airport Extension*

    *Ongoing projects