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									            Innovative Approaches for Physical Considerations / 1



               Professor Dr. Nor Aieni Haji Mokhtar


It is a generally known fact that, our planet Earth is covered with
71 percent water. Continuous energy dissipation takes place
where the land meets the sea. As a consequence, coasts are
subject to deformation, of which coastal erosion poses
greater problems. This must be combated to prevent loss of
highly valuable land and properties, structures and
recreational areas. It has been well interpreted that possible
causes for erosion include sea level rise and coastal
subsidence, natural weathering, reduced sediment discharge
from rivers into the coastal areas, and human impacts, such as
caused by structures.
        Shoreline naturally, seasonably, and variably, gain and lose
sediments over the years. Eroding shoreline is caused tidal changes
aggravated by winds and wave forces during storms. Due to
human interference, coastal erosion has also been intensified
via dredging and mining activities for the purpose of land
reclamation as well as removal of vegetative cover for economic and
infra-structural development. With rapid increase in development
and economic activities along the water body areas, the problem of
2 / Siri Syarahan Perdana Profesor

coastal erosion is more persistent and increasingly demands our
serious attention. Thus, there is a need to protect our land, the
nation’s greatest asset, from being washed and eroded away.
       Malaysia, being a maritime country with a total stretch of 4800
km coastline is experiencing threat of shoreline erosion of about
29 percent. Figure below shows the distribution of coastal
erosion experienced in the various states of Malaysia.
                      Length of eroding shoreline (km)










         Figure 1
   Distribution of                                         0
  coastal erosion                                                    States in Malaysia

Figure 2      Threat of coastal erosion has led to destruction to public
properties and loss sediments info the sea

       In the last 20 years, the economic consequences have grown
steadily that results in an increase in the utilisation of Malaysia’s
nearshore areas for agriculture, industries and commerce by 64
percent. Growing wealth and improved means of transportation have
brought the beaches within our reach as resort areas for almost
everybody in the industrialised countries. At the same time, the
             Innovative Approaches for Physical Considerations / 3

recreational values of the same areas are threatened by pollution of
many kinds and often erosion, too (Figure 2). The search for and
production of oil and gas from the continental shelf has further
emphasized that the sea is increasingly becoming an important part
of our life in the planet. In addition, the expansion of world trade in
general and the trade of developing countries in particular, require
constructions of large number of harbours and terminals, and that
over a rather short span of years. The lack of sheltered areas with
sufficient water depth to accommodate large tankers and bulk
carriers has led to the construction of terminals for these ships
and much more exposed locations than were previously
considered feasible.
        The Malaysian government, particularly the Department of
Irrigation and Drainage, has recognized the threat of critical coastal
erosion under Category 1 and acted to counter it and to limit its
consequence. This is clearly spelled out in the National Coastal Zone
Management Plan and Guidelines (Garis Panduan JPS 1/97, 1997).
To balance the need for infra-structural development and to
minimize the impacts of coastal erosion, it is a mandatory
requirement by the approval authorities that certain investigative
studies need to be carried out to assess the viability and to provide
detailed engineering drawings for optimum design support.
        In the last decades, major contributions to the design
practice have been made, thanks to new research facilities like a
large scale wind wave flumes, turbulent flow measurement
devices, numerical models, etc. Progress has been made in
the scientific basis of our knowledge that is empirical, based
on experiments and experience. Theoretical approach
of the phenomena, by understanding the process and the
design of protections especially in the unusual cases, is a mix
of science and experience. Computer models play an increasing
role in engineering. For a hydraulic engineer, however, a
sheet of white paper and a pencil are still essential, especially at
preliminary stage of a design. A hand-made sketch of a
current or wave pattern is as valuable as the application of
4 / Siri Syarahan Perdana Profesor

calculation rules. For both, a good insight into the physics of the
processes involved is indispensable.

The Need to Investigate and Counter Problems in Designing
and Constructing Coastal Protection Structures

Coastal engineering is a field for which there is no code of practice.
Some standard procedures exist e.g. Coastal Protection Manual, US
Army Corps (CERC, 1984), but any applications of standard practice
is limited because solutions are necessarily site-specific. Thus, every
project becomes a unique challenge. A healthy proportion of
ingenuity and common sense is necessary. It is not possible to
develop solutions on a prototype scale, as one might design for a
breakwater, for example. We do not have design codes; we cannot
define input conditions with sufficient accuracy, and we are
uncertain of the performance. Trial and error solutions on a
prototype scale are not acceptable, since the costs involved in
errors and necessary project changes are normally prohibitive.
Thus, most of the coastal projects are carefully designed using
models. The two basic types of models are physical models and
numerical models. The problem is solved or the design is made
using these models, guided by experience we have and based on a
limited suite of measured prototype conditions. The prototype
measurements enter the design as data and it is very important
to be able to distinguish the difference between the input data
and calibration data. The physical models are meant for the detail
design of coastal structures whilst the numerical or hydrodynamic
models are meant to confirm the layout design and the prediction
of impact or performance of the structures.
        The challenge is to use the available tools to provide the best
product. All tools have shortcomings and it is essential that
each of the tools used is in the most appropriate manner so
that it brings its own strengths to design and its weaknesses
minimized. This paper will outline research carried out by the author
and her team members and highlights some ways to optimize the
output and to increase confidence in our designs for the future.
             Innovative Approaches for Physical Considerations / 5

       In this era of new millennium, it is a good time to reflect upon
the research carried out on coastal engineering design methods and
the tools that have been used particularly at the Coastal & Offshore
Engineering Institute, Universiti Teknologi Malaysia, Kuala Lumpur.
It has been observed that the tools, namely physical modeling,
numerical modeling and collection of field data all have its own
serious shortcomings. This paper a discusses physical modeling
studies of some coastal protection structure types and presents
detailed discussion on the development of a revetment system


This section provides an insight to the theoretical background and
common understanding reported by previous researchers. A
review of aspects of managing beach deformation controlling
works, the impacts of large waves at the shoreline, the impacts
of wave breaking and wave transformation in the surf zone
and wave-structure interaction are presented. The design
philosophy and design methodology for coastal protection
structures breakwaters, groynes, revetment and artificial reef,
aspects of physical modeling and components for design
considerations including data requirements from the site conditions
will be highlighted. A summary of projects undertaken and
facilities available at COEI are also given.

Beach Deformation Controlling Works

Topographic change to be controlled are related to problems such
as erosion of foreshore due to storms, local erosion due to current,
sedimentation in harbour and channel, blockage of rivermouth, etc.
Coastal protection structures have been used to trap longshore
sediment movement at one location whilst erosion
persists at the downstream side.
        The procedure is to determine which method should be
adopted from various works. The basis for consideration in the study
is as follows:
6 / Siri Syarahan Perdana Profesor

(i)     Past and present characteristics of beach deformation and
        sediment movement of the objective beach. There is a need to
        analyze the cause of deformation and the predominant
        sediment movement (direction and mode) to be controlled on
        the basis of sounding data, bed material characteristics, river
        run-off, and weather sea conditions. We need to fix various
        input conditions, such as characteristics of beach, bathymetry,
        incoming waves, that will be used in the assessment of the
        effect of the structures in the surrounding coast.

(ii)    Selection of various methods: Based on analysis in (i), the
        choice depends on functions of structures to control fluid
        motion and sediment movement.

(iii)   Evaluation of the effects of the selection on the surrounding
        coast: Evaluation and assessment can be made by numerical
        modeling or by hydraulic model experiments (physical model).
        Although many studies have been conducted, by numerical
        method for example, prediction for fluid motion close to
        structures with sufficient accuracy is limited. By physical model
        or experiments, on the other hand, unsolved problems still
        remain especially related to movable bed, similitude law and
        reproducibility of the phenomena in the field in the laboratory.
        Hybrid method sometimes adopted whereby topographic
        change is predicted numerically by using waves and current
        fields obtained in the hydraulic experiments might become
        effective tool.

(iv)    Other evaluation and determination of evaluation criteria.

      The cost of construction, view, durable years, water quality
environment, and relation to fishing industry are raised in these items.
Standard evaluation criteria are not established and for these
reasons, they are determined on case-by-case basis. Figure 3
shows the general procedure for determining the work to control
beach deformation prior to construction.
                 Innovative Approaches for Physical Considerations / 7

           (i)       Investigation of present state
                     and characteristics of past topographic
                     changes and sediment movement

           (ii)     Selection of countermeasures

                                                           Determination of
                                                           standard criteria

           (iii)    Assessment for the effect of shore protection
                    And effect on surrounding coast

           (iv)      Assessment of other issues



Figure 3      A flow diagram of procedures for selection of measures to
control beach deformation

Depending on the scale of the project, the scope of investigation

1.    Measurement and analysis of oceanographic parameters and
      beach profile.
 2.   Prediction of extreme wave climate from wind record.
 3.   Joint probabilities of waves and tides.
 4.   Modeling of wave transformation in shallow water.
 5.   Hydrodynamic simulation of sediment transport.
 6.   Design of structures.
 7.   Fixed or preferably mobile bed-physical modeling of beaches.
 8.   Detailed design.
 9.   Construction methods.
10.   Coastline management and monitoring.
8 / Siri Syarahan Perdana Profesor

Types of methods or structures used for various mitigative
measures include:
• Seawall of various types.
• Armoured slopes and embankments or revetments.
• Groynes.
• Detached breakwaters.
• Beach nourishment.

       Coastal erosion is a localised problem and methods to
combat the problem vary from one location to another. It depends
on climatic condition, i.e. wind, wave and current, soil conditions
and other environmental factors.
       The existing shore protection structures include rock
revetment, gabion, Bakau pile seawall, concrete seawall, stone
masonry groyne, timber groyne, scrap type seawall with timber piles,
rubblemound breakwater and pre-cast concrete block revetment.
Rubblemound or rock revetment has been a traditionally an
acceptable method of coastal defense. But the local supply of
rocks is limited,and the method is less environment-friendly,
which is due to inaccessibility to water body and lack of beach. Beach
nourishment is a “soft” method and is environment-friendly but it
has maintenance problem of finding enough quantities of sand at
distinct time intervals like once in every three to five years.
       Pre-cast concrete systems are getting more popular these days
as their geometric shapes can be engineered to suit the design
criteria. This approach enabled industries for construction,
manufacturing and marine to flourish and develop indigenous
products suitable for the environment. Table 1 Shows the various
methods of coastal protection methods being used in Malaysia.

Large Waves Impact at the Shoreline

Long waves in channels have served to provide much of the impetus
to the study of waves. The wave motion in a channel is
governed by mild-slope equation. The propagation of waves in
channel of various configurations (rectangular, triangular, trapezoidal
              Innovative Approaches for Physical Considerations / 9

  Table 1 Some methods of coastal protection being used in Malaysia

Rock/Rubblemound Revetment              Beach Nourishment

Flex-Slab revetment system              Rubblemound breakwaters as Groynes
                                        - perpendicular to shore

Tripod                                  Rubblemound Offshore/
                                        Detached breakwaters – parallel to shore

Sine-Slab revetment system              A pair of rubblemound breakwaters
(New Product – Made in UTM, Malaysia)   as groynes for harbour protection
10 / Siri Syarahan Perdana Profesor

and arbitrary prismatic channels) have been investigated by many
researchers ((Darymple R.A, Kirby J.T,Li, Li, (1994), Matthew &
Akylass (1990), Isaacson (1978), Berkhoff, 1972, Peregrine (1968),
Lamb (1945), Russel S, (1844) and Kelland as early as 1839)).
Wave propagation can be modeled using a numerical eigen
function expansion. More recent work (Norazizi Mohamad and
Noraieni Mokhtar, 2000) had examined the short waves, such that
the depth/wavelength ratio can exceed 1/20 or straight channels with
rectangular and trapezoidal cross-sections. The water surface
displacement created by uniform wave train normally incident on
the channel and this is the resultant of superposition of the
eigenmodes, determined numerically and experimentally using
Particle Image Velocimetry technique (PIV) from the lateral
eigenvalue problem. Short waves in a channel can present
navigational problems and may excite harbour oscillations.
Sloping sidewalls have been shown to produce edge wave motions
excited by the incident wave field. These edge waves have a
different wavelength than the incident wave field and they are
the largest at the shoreline, hence providing potential for greater
wave damage and erosion there. Thus channel sidewalls may
reduce much of this wave energy, if they are sufficiently porous
or if they are sloped. Though wave breaking has been ignored in
this linear analysis, it is of importance in the field and will be
discussed next.

Impact of Wave Transformation and Wave Breaking in
the Surf Zone

The waves generated by winds propagate for a distance from the
ocean and approach a beach. This random sea is a dominant force
to the beach profile evolution and many other coastal
engineering subjects. As the water depth become shallow,
the orbital motion of water particle commences to have an
influence on the sea bottom material. Then, waves tend to dissipate
energy by friction, release most of the energy by breaking
and cause a change in the beach profile (refer to Figure 4).
            Innovative Approaches for Physical Considerations / 11

   Uniform flow        Tidal current        Orbital motion   Breaking wave

                                 Figure 4

       Through these physical processes, a wave height distribution
across the shore may change to a non-Raleigh distribution. In the
last few decades, numerous studies have been done on wave
transformation and breaking waves. Therefore, wave height
distribution for regular and random waves can be numerically
predicted to some degree. As shown in Figure 5 below, interesting
phenomena such as hydraulic jump and bore formation
relates to the wave and energy transformation analogous to
wave run-up and roller or undertow effect due to wave breaking and
wave run-down respectively.

                                                             Wave celerity

           Hydraulic jump                                    Bore

Figure 5   The predominant phenomena that relates to the wave and
energy transformation distribution

In contrast to a number of wave models, practical engineering
methods for beach profile evolution due to random waves are still
few, for instance Stive and Battjes (1984), Brian and Kamphuis
12 / Siri Syarahan Perdana Profesor

(1990) and Sato and Mitsunobu (1991). In fact, for convenience and
engineering usefulness, regular wave conditions are widely accepted
for physical modeling as well as numerical experiment for
cross-shore sediment transport. However, the mild transformation
of random waves may result in the mild bar profile compared
with the distinct bar-trough feature due to regular waves.
         With the advent of technological innovation, the availability of
powerful and fast PCs and data acquisition systems, simulation
of beach profile evolution due to random waves is no longer
unrealistic approach and has become practical even if a little
bit complicated (Kajima et al., Dette and Uliczka, 1986, and Krauss
et al., 1992). The Goda random wave model predicts information on
several kinds of representative wave height distributions, for instance,
maximum wave, significant wave, and mean wave height
distributions. A cross-shore sediment transport model that is related
to the wave energy flux is coupled with a mass conservation
equation to obtain a new beach profile (Nishi, Sato and Wang, 1994).
Based on Goda’s wave breaking criterion, later modified by Sato
and Kobe (1983), the slope term in the breaking limit to the absolute
value of the local beach slope is found as follows:

Χb=Hb/HO=Α/[HO/LO]{1    – exp(–1.5 (πh/HO)(HO/LO)(1+κ|tan θ|4/3]}...(1)

       where Χ is the normalized wave height, HO is the significant
wave height, κ = 15, LO= gT2/2 π, and the coefficient Α takes the
value of 0.17 for regular waves. In the random wave breaking, Α is
set to 0.18 for the upper breaking limit of random waves at Χ =Χ1
and 0.12 for the lower breaking limit Χ = Χ2.
       Proper development or protection of coastal zones generally
requires us to evaluate beach processes as accurately as possible.
Prediction of beach processes under sheet flow condition is extremely
important, because significant short term beach deformation is
caused by large waves, under which the sheet-flow sediment
transport is usually predominant. In addition, under such conditions,
we cannot discard the symmetry of near-bottom orbital
           Innovative Approaches for Physical Considerations / 13

velocity due to wave non-linearity and the presence of undertow
particularly in the surf zone (Watanabe, 1994). Non-linear wave
transformation on a sloping bed can be computed by a set of
Boussinesq-type equations including a breaker-induced energy
dissipation term in the surf zone, the undertow (return flow near the
bed) usually develops to compensate the shoreward mass
transport accompanying the breakers. Since the concentration of
suspended sediment is very high near the bottom, the effect of the
undertow on the sediment transport should be inevitably taken into
consideration. A Ph.D Thesis (Mir Hammadul Azam, 1998) has
confirmed this effect of suspended particles in dissipating the wave
energy on flat and mild sloped beds beach. The soft mud
bed shows resistance against shear force applied on its surface up
to certain point. Above this critical point, bed starts to erode.
       The study experimentally examined several hydrodynamic
properties and the suspended sediment concentration under
breaking wave condition. Numerical investigation was also made to
ascertain its effectiveness and to understand the role of hydraulic
parameters on surf zone dynamics. Wave deformation, mean
flow generation and suspended sediment concentration were
observed. The results showed that the ratio of the incipient breaker
height to the mean water depth (H/D)b was an important parameter
that described the intensity of wave breaking. Wave energy
dissipation rate was higher when the value of (H/D) b was
higher than 0.78. The estimated roller size over a flat bed was smaller
than that of the typical surf zone. The magnitude of mean horizontal
flow and degree of turbulence below the trough level was
dependent on (H/D)b. The mathematical model study included
the solution of the equation of motion and turbulence transport
equation in a coupled form. The model was developed for a
quasi-steady situation over a 2-D vertical plane. The results of the
study provided guidance for the calibration of model. Model
predicted results were compared with experimental measurements.
The comparisons were satisfactory. Application of the model showed
14 / Siri Syarahan Perdana Profesor

that the turbulence under breaking wave was damped by the increase
of sediment concentration in the water. The turbulent field was
remarkably sensitive to vortex size under broken waves. Findings of
the study help to understand the hydrodynamics in a distinct case of
breaking that occurs over mud flat. The model study can assist in
understanding the role of important parameters, which have
significant effect on bed erosion and sediment transport.

Wave - Structure Interaction

Shallow coastal areas are extremely dynamic regions where fluid
motions associated with both surface waves and currents
interact with the bottom sediments. An extended form of the
Boussinesq equations have been developed to mobile boundary
flow model for the computation of wave deformation due to

          reflected wave           Hi
          Hr                       incident wave
                           run-down hs


                                               Wave overtopping

                                                   Wave transmission

    Figure 6     Definition of wave run-up and wave reflection, wave
    overtopping and wave transmission
            Innovative Approaches for Physical Considerations / 15

combined effects of refraction, diffraction, reflection, breaking
waves, and wave current interactions from very shallow
conditions to intermediate depth over slowly varying slopes of
bed (Antunnes do Carmo and Seabra-Santos 1994).
       There is a strong interaction between a wave and a wave
damping structure like a breakwater. This interaction is visible in front
of the structure (reflection), on the slope of structure (run-up) and
behind the structure (overtopping and transmission) [http://
www.vssd.nl/hlf/PDFs/f011h10.pdf]. Even if a breakwater structure
is stable under the action of waves, there is an interaction between
the structure and the wave field near structure. The discerning
phenomena that lead to different wave patterns in the vicinity of the
structure include wave reflection, wave run-up, overtopping and wave
transmission as illustrated in Figure 6.
       Wave reflection plays a role in front of the structure, wave
run-up takes place on the slope of structure, overtopping and
transmission are important for the area behind the structure. It is
then useful to analyze which phenomenon influences the design
problem in question. Too often, formulae for run-up or overtopping
are used when the designer wishes to address wave transmission.
The wave motion in front of a reflecting structure is determined
by the reflection coefficient K r that is related to the ratio of
reflected wave height over incident wave height Hr/Hi. For a 100
percent incoming wave energy is reflected, H r /H i = 1, this
is valid for vertical wall with infinite height. The reflection
coefficient for sloping structures, rough or permeable structures
and structures with limited crest level is smaller.
       The extensive breaking of waves will result in a spectrum that
hardly shows a clear peak. A lot of energy has been shifted
to the lower frequencies. Definition of wave peak becomes
difficult, but remains important because of the influence
on run-up. Wave run-up is the phenomenon in which an incoming
wave crest runs up along the slope up to a level that may be
higher than the original wave crest. The vertical distance
between Still Water Level (SWL) and the highest point reached
16 / Siri Syarahan Perdana Profesor

by the wave tongue is called the run-up “z”. We can only speak
of the run-up when the crest level of the structure is higher
than the highest level of the run-up. Run-up figures are mainly
used to determine the probability that certain elements
of the structure will be reached by the waves. Run-up can be
indirectly used to estimate the risk of damage to the inner
slope of the structure. It is not acceptable for a large
percentage of incoming waves to reach the crest and
subsequently caused damage to the inner slope. In most
cases, the 2 percent run-up is given: the run-up level that is
exceeded by 2 percent of the incoming waves. In
Netherlands, research on run-up has attracted a lot of
attention, particularly for assessing the required crest
level for dikes and seawalls. (Battjes, 1994, Anonymous,
1998). The run-up on a smooth impermeable slope
is expressed as

      Z2% = 1.6 ξop HS                                      ...(2)

With a maximum of 3.2, in which Z2% = run-up level exceeded
by 2 percent of the waves, H S = significant wave height and
ξop = breaker parameter for deep water and peak period. The
run-up level can effectively be reduced by designing a berm at
still water level, by increasing the roughness of the surface,
or by increasing the permeability of the structure. Waves
approaching the structure at an angle will also lead to
reduced run-up levels. This reduction is expressed in terms of
reduction factor γ . The effective run-up is then calculated by
multiplying the value for smooth impermeable slopes by the
correction factors. Run-up levels on rough, impermeable/non-
porous slopes can easily be calculated by applying the
correction factors as indicated in Table 2. The factors are valid
for ξ op < 3 to 4, above the value of 4,the reduction
is no longer applicable.
       For rough slopes with limited permeability/porosity, it is
possible to apply the general run-up formula and to make
corrections as long as ξop < 3 to 4 as shown in Table 3.
              Innovative Approaches for Physical Considerations / 17

                  Table 2 Correction factors for roughness

                                    Structure                             γ
 Smooth, impermeable(asphalt/closely pitched concrete blocks              1.0
 Open stone asphalt etc.                                                 0.95
 Grass                                                                 0.9-1.0
 Concrete blocks                                                          0.9
 Quarry stone blocks (granite, basalt)                                 0.85-0.9
 Rough concrete                                                          0.85
 Source: Wave-structure interaction; Breakwaters & closure dams

   Table 3 Correction factors for roughness and permeability/porosity

                                   Structure                              γ
 One layer of stone on an impermeable base                             0.55-0.6
 Gravel, Gabion mattress                                                  0.7
 Rip-rap rock, layer thickness n>2                                     0.5-0.55

Calculation of wave transformation through a submerged
breakwater is based on energy (E) conservation. The equation
in a steady state is expressed as

 / Χ E (cg cos θ+U)+ /              y E (cg sin θ+V)+Sxx U/       Χ   +Sxy ( V/   Χ

 U/ y) + Syy V/ y = – D                                                       ...(3)

Where Sxx, Sxy and Syy are the radiation stresses, cg group velocity
(U,V) depth averaged mean current velocities in the x and y
directions and θ is the angle of wave incidence.
       The energy loss is thus dependent on the vertical and
horizontal velocities as well as the angle of wave incidence θ. When
the incident waves break on the submerged breakwater, energy loss
by wave breaking D b must be added to D. Thus requires
understanding of the following:
(a) Critical depth on the submerged breakwater for wave breaking.
(b) Two-dimensional wave transformation on a permeable layer
     and submerged breakwater.
18 / Siri Syarahan Perdana Profesor

       In terms of stability, there are two types of breakwaters:
statically stable low crested breakwaters (exposed) and Statically
stable submerged breakwaters. Stability depends on

      H/d = (2.1 + 0.1 Sd) exp (–0.14 NS)                       ...(4)

H = Crest height of structure, d = water level, S d = accepted
damage level.
       For static stability, NS = 1 to 4 (designed for no damage/
displacement of units). For dynamic stability, N S = 6 to 20
(developed profile). The stability criteria, designs are based on the
guidelines provided by Shore Protection Manual, US Army Corps of
Engineers, 1987 and Manual on use of Rock in Hydraulic
Engineering, Centre for Civil Engineering Research Codes, 1995.
       Overtopping is defined as the quantity of water passing
over the crest of a structure per unit time Q (m3/s). The quantity
of water is often a linear function of the length of structure, it is
expressed as a specific discharge per unit length (m3/s/m). The
study of overtopping quantities is related to the stability of
the inner slopes of structures such as dikes. When designing
breakwaters, thequantity of overtopping may be important
to determine the capacity of the drainage facilities required for
port areas directly protected by breakwater, or to assess the risk
to people or installations on the crest of the breakwater.
Although the assessment of these sometimes-subjective
risks on the basis of model experiments is difficult, it is
possible to derive a trend. The quantity of wave overtopping
is largely influenced by the nature of the outer slope of the
structure. An added effect is the influence of the shape and
nature of the crest (presence of the crown wall). Unfortunately,
various model investigations (Bradbury et al., 1988; Owen,
1980; Van der Meer and Stam, 1992; De Waal
and der Meer, 1992, and Aminti and Franco, 1994) including
those performed at COEI were carried out with varying
           Innovative Approaches for Physical Considerations / 19

structures. Therefore, it is not possible to derive a generally
applicable formula for overtopping. As a first approximation
by using the formula of Bradbury et al., (1988) which is
valid for a structure without a crown wall,

      Q* = a (R *)–b                                              ...(5)
               Q    √ Som
      with Q* √[gH 3] 2π                                         ...(6)


      R* = (RC/HS)2 √Som                                          ...(7)
in which R* = dimensionless crest freeboard, RC = crest freeboard
relative to SWL in m, HS = significant wave height, Som = deep
water wave steepness, based on mean period, Q = specific
discharge in m3/s/m and Q* = dimensionless specific charge.
Relevant values of the coefficients a and b depend on
structural details.
       It must be kept in mind that a vertical face breakwater
causes a lot of spray when hit by a wave. The spray may also be
blown over the breakwater. This effect is normally difficult to be
       Wave transmission is the phenomenon in which wave energy
passing over through breakwater creates a reduced wave action in
the lee side of the structure. This will happen when considerable
amount of water are overtopping the structure. Wave transmission is
also possible when the core of the structure is very permeable and
the wave period is relatively long. It is specifically the influence of
these two factors that for a long time has prevented the derivation of
an acceptable formula for wave transmission by rubblemound
breakwaters. In practice, limits of transmission coefficient kt are
about 0.1 and 0.9. It is remarkable that for Rc = 0, which represents
a structure with the crest at SWL, the transmission coefficient is
in the order of 0.5. This means that a relatively low structure
is already rather effective in protecting the harbour area behind the
20 / Siri Syarahan Perdana Profesor

breakwater. In combination with the requirements for tranquility
in the harbour, the designer can decide on the minimum
required crest level.
       For traditional low crested breakwaters, the formula
deduced by Daemen (1991) relates transmission coefficient to a
number of structural parameters of the breakwater. To account
for permeability, the freeboard Rc of the breakwater was made
dimensionless by dividing it with the armour stone diameter and it
reads as follows:

       Kt = a [Rc/Dn50] + b                                       ...(8)

        In which K t = H st /H si = transmission coefficient,
H is = incoming significant wave height, H st = transmitted
significant wave height, Rc = crest freeboard relative to SWL,
Dn50 = nominal diameter armour stone, B = crest width, Sop = wave
steepness. The values of a and b then varies for permeable and
permeable structures.
        The high pressure from the wave breaking, run-up action and
the responding high pressure created below the revetment
(filter layer) has to be neutralized and the associated energy
to be dissipated. This effort is to prevent the structural slope
and the protective layer from damage and perhaps total failure or
collapse (Refer to Figure 7).
        Wave attack on revetments will lead to a complex flow over
and through the revetment structure (filter and cover layer). During
wave run-up the resulting forces by the waves will be directed
opposite to the gravity forces. Therefore the run-up is actually less
hazardous than the wave run-down.
        Wave run-down will lead to the following two important

(1)   The downward flowing water will exert a drag force on the cover
      layer and the decreasing freatic level will coincide with a down-
      ward flow gradient in the filter. Thus it may result in sliding.
(2)   During maximum wave run-down, there will be an incoming
      wave that a moment later will cause an impact. Just before
           Innovative Approaches for Physical Considerations / 21

                                                     cover layer
                                                             phreatic level
                                                 s n
                                       low un-dow
                                        at r

                                             high pressure
                             r               below revetment
                        filte a

              Pressure development in a revetment structure

             breaking wave                        pressure head on the slope

                                       ds    Qf

                                                         maximum difference in
                         e                               pressure on the cover layer

                             Schematization of pressure head on slope

                     Schematised development of S-profile and possible
                     local sliding in the base

        Figure 7      The action of waves upon interacting with
        a sloped structure of a breakwater or revetment

the impact, there is a “wall” of water giving a high pressure under
the point of maximum run-down. Above the run-down point the
surface of the revetment is almost dry and therefore there is a low
pressure on the structure. The high pressure front will lead to an
upward flow in the filter. This flow will meet the downward flow in the
run-down region. The result is an outward flow and uplift pressure
near the point of maximum wave run-down.
22 / Siri Syarahan Perdana Profesor

The schematized situation can be quantified on the basis of the
Laplace equation form linear flow:

       ∂2Φ + ∂2Φ = 0
       ∂y2   ∂z2                                                         ...(9)

       Φ    = Φb = potential head in the filter
       y    = coordinate along the slope (m)
       z    = coordinate perpendicular to the slope (m)

       The uplift pressure is dependent on the steepness and height
of pressure front on the cover layer (which is dependent on the wave
height, period and slope angle), the thickness of the cover layer and
the level of the freatic line in the filter or a slab structure. The
equilibrium of uplift forces and gravity forces leads to the following
(approximate) design formula (Pilarczyk et al., 1998):

       Hscr             0.67
            =f D               with Λ ( bDk ) 1/2                       ... (10)
       ∆D      ∆ ξ op                   k’

       or   Hscr
                 =f   D k’     0.33
                                      ξ op 0.67 or Hscr = F ξ op 0.67   ... (11)
            ∆D        b k                          ∆D

where Hscr = significant wave height at which blocks will be lifted out
      ξ op = tan α /(Hs/(1.56Tp2 ))= breaker parameter [–]
      Tp = wave period at the peak of the spectrum [s]
      ∆ = leakage length [m]
      ∆ = (ρS – ρ)/ρ = relative volumetric mass of cover layer [–]
      b = thickness of a sub-layer [m]
      D = thickness of a top layer [m]
      k = permeability of a sub-layer [m/s]
      k’ = permeability of a top layer [m/s]
      f = stability coefficient = KD mainly dependent on
             structure type, tan α and friction [–]
      F = total (black box) stability factor [–]
            Innovative Approaches for Physical Considerations / 23

       To evaluate the structural response y using wave load
approach, there are two practical design methods available:
the black box model and the analytical model. In both cases,
the final form of the design method can be presented as critical
relation of the load compared to strength, depending on the
type of wave attack:

       Hs        = function ξ op
       ∆D                                                        ...(12)

For revetments, the basic form of relation is:

       Hs        = F
                   ξ              with maximum Hs        = 8.0   ...(13)
       ∆D   cr         op
                                               ∆D   cr

in which F = revetment (stability) constant [–], Hs = (local)
significant wave height [m], ∆ = relative density [–] , D = thickness
of the top layer [m], and ξop= breaker parameter [–].
        The advantage of black box design formula is its simplicity.
The disadvantage, however, is the value of F is known only very
roughly for many types of structures.
        The analytical model is based on theory for placed stone
revetments on a granular filter (pitched blocks). In this calculation
model, a large number of physical aspects are taken into account.
In short, in the analytical model nearly all physical parameters that
are relevant to the stability have been incorporated in the leakage
length Λ = ( bDk /k’). The final result then F = f(Λ). To apply the
design method for placed stone revetments under wave load to
other systems (CUR/TAW, 1995), the following may be adapted:

• The revetment parameter F
• The representative strength parameters ∆ and D
• The design wave height Hs
• The representative leakage strength Λ
• The increased factor on the strength
24 / Siri Syarahan Perdana Profesor

Design Philosophy and Methodology: Towards Innovative

The rigorous approach of innovation towards commer cialization
of Research & Development (R & D) for coastal protection structures
involves basic research and understanding of the coastal processes
and related phenomena for the wave, current-structure interaction,
structural designing aptitude and common sense. It is based on
previous experience of others for the application of the
technologies, model tests and technological development for
industrial application, prototype development and field tests,
production of prototypes, and eventually competitive market
entry, sales and technical services.

Design Philosophy

A bank, eroding due to wave action, can be protected by making a
revetment (Case A) or by constructing a wave attenuator
(breakwater) perpendicular or parallel to the shore (Case B) or in
front to the bank (Case C). The later was normally chosen when the
“natural” look of the bank has to be preserved. Revetments and
Breakwaters are constructed to protect land area (population
and economical values) against erosion or inundation due
to storm spells. There is still much misunderstanding on the
use of these structures and their possible disadvantages
related to the disturbance of the natural coastal processes
and even acceleration of beach erosion.
        However, in many cases, when the coastal area is under threat
of further erosion or endangered by inundation such as in Nether-
lands, leading to high economical and ecological losses, the struc-
tures can be a “must” for survival. Absolute safety from
storm surges or monsoons is nearly impossible to realize. Thus,
it is more enlightening to examine the probability of failure of
certain defense systems and to come up with value-added
systems that have been optimized in terms of performance,
workability, practicality, and cost.
        Generally, the principle in the design is based on the
            Innovative Approaches for Physical Considerations / 25

perception that the structure is to withstand the hydraulic forces due
to wave attack (Stability Criterion), capable of accommodating
foundation deformation (Flexibility Criterion) and does not suffer
loss of function due to ageing during its design life (Durability
Criterion). It is also recognized that a common failure mode of
modular concrete blocks is due to uplifting of the individual blocks
and slope failure due to slip circle. Thus the design also focus
on the interlocking system that would give better hold so as to allow
for no damage or displacement of individual units and system
stability and flexibility via sediment trapping and automatic drainage
features to accommodate impacts of nature’s forces and pressures.

Design Methodology

In designing coastal protection structures, the following
aspects have to be considered:
(i) The function of the structure.
(ii) The physical environment.

                          FUNCTIONAL REQUIREMENTS
    OBJECTIVES                                    CRITERIA
           Shoreline stabilization                      Performance
           Backshore protection                         Technical feasibility
           Inlet stabilization                          Economic feasibility
           Harbour protection                           Sosial/Political stability

       DESIGN                        SIMULATION                     EVALUATION

      CONSEPTUAL                       MODEL                          CRITERIA
        DESIGN                         LEVEL 1

     PRELIMINARY                       MODEL
       DESIGN                          LEVEL 2                      OK

                                                              YES          REDESIGN

     ENGINEERING                       MODEL
                                       LEVEL 3                             GO TO
                                                                         NEXT PHASE

                                                                                      Figure 8 The
                               NATURAL ENVIRONMENT                                    methodology
26 / Siri Syarahan Perdana Profesor

(iii) The construction method.
(iv) Operation and maintenance.

      The main stages of design, simulation and evaluation can
be identified in the design process as shown in Figure 8.

Design Criteria

The innovative approaches for the physical considerations of
structures involve basic research, comparative studies of existing
designs, model development, trial simulation tests, prototype
development and field testing. Consequent requirement is the
resulting structural design should be effective and efficient.
Effective means that the structure should be functional both for
the user and the environment. Efficient means that the cost of the
effective structure should be as low as possible and that the
construction period should not be longer than necessary.
Combination of this criteria of effective and efficient is “value for
money”. An integrated design process can be presented as in
Figure 9 below

  Initiative                Functionality   Environment       Cost
  Feasibility Study
  Provisional design
  Final Design       Time
  Detailed design
                                      Technology   Construction

Figure 9       An integrated design process for optimizing effectiveness
and efficiency

Geometrical Design

Selection of the structural concept depends on the function, the
local environmental conditions and the construction constraints. The
governing criteria are the technical and economic feasibility for the
           Innovative Approaches for Physical Considerations / 27

project under consideration. The function of the structure is mainly
to protect the hinterland against the adverse effect of high water and
waves. If the high-water protection is required, the structure should
have a height well above the maximum level of wave uprush
during the storms. This normally calls for high crest elevation. If,
however, some overtopping is allowed in view of the character of
the hinterland, the design requirement is formulated in terms of
the allowable amount of overtopping. Obviously, crest elevation
can be reduced considerably in this case.
       The shape of the cross-sectional profile of the structure is an
influence on the distribution of wave forces, and thus, also influences
the choice of material (type of protective units and their dimensions)
suitable for slope protection (revetment) and the height of the
structure. The gradient of the slope must not be so steep that the
whole slope of the revetment can lose stability (through
sliding). This criterion gives, therefore the maximum slope angle. More
gentle (flatter) slopes lead to a reduced wave-force on the revetment
and less wave run-up; wave energy is dissipated over
a greater length. A similar effect can be obtained by applying a
berm (trapezoidal profile). Another point of economic optimization
can be the available space for structural construction of
improvement. All these factors should be taken into account
in optimizing structural slope. A common Dutch practice is to apply
a slope of 1 : 3 on the inner slope and between 1 : 3 and 1 : 5 on
the outer (seaward) slope. The mild slopes also minimize the scour
at the toe of the structure (lower reflection). The minimum crest
width is 2 m.
       By studying the weaknesses of the existing systems,
innovalue ideas for the elaboration of the design process depends
on specific local circumstances, type of area, its development
(economic value), availability of equipment, manpower and
materials, etc. The cost of construction and maintenance generally
is a controlling factor in determining the type of structure to be
used. The starting point is the cooperation with the client or
future manager of the project.
28 / Siri Syarahan Perdana Profesor

The Field/Site Condition Studies

The detail requirements for reliable data in detailing the design of
coastal protection structures comprised of:
• Hydrographic surveys - Bathymetric Charts, shoreline,
   seabed contour or seabed topography.
• Hydraulic studies - water levels, tides, waves currents,
   sediment transport.
• Geo-technical studies - sediment sampling, slope stability.
• Natural environment and socio-economic impacts.
        It is very pertinent to obtain possibly, as certain the extreme
values of certain return period (e.g.,10, 20, 50 and 100 years) of
Highest Astronomical Tides (HAT), Lowest Astronomical Tides (LAT),
significant wave height and wave period, Mean Sea Level (MSL) in
order to optimize the design by simulating the extreme conditions
experimentally. Thus, values of run-up and run-downs, overtopping,
stability coefficient and so forth can be gathered.

Option for Rock/Rubblemound or Pre-cast Concrete Blocks for
Armoured Slopes

Traditionally, in developing countries, rubble-mound or rock
revetment has been an accepted method of coastal defense. Though
in terms of economic of use it is acceptable, but the supply of rocks
is limited and the method is less environmental friendly as this means
blasting off the rocks from the quarries. Alternatively, various types
of articulated blocks have been designed and prefabricated in the
form of pre-cast concrete blocks. These blocks provide a higher
stability coefficient value KD, compared to rocks, thus, allowing the
use of a lighter weight of the blocks as well as provision for
additional esthetical design features that can provide the strength
against the impacts of the waves, current and tidal changes. The
production of pre-cast concrete and composite systems also
provide a new avenue for manufacturers in their product line of
business. Eventually, a design engineer has to decide on the
product performance over the costs or vice versa. The ultimate
aim is to retard erosion and to break the impact of waves as well as
             Innovative Approaches for Physical Considerations / 29

entrap sediments. Thus, an approachable solution is sought
towards the design and development of innovative systems
that are aesthetic multifunction shoreline structures.

Case A - Analytical Design Method of Block Revetments

With or without protection, coastal banks are proned to damage
as they are continuously exposed to various attacks from the waves.
The slope instability, collision or aggression by vessels,
subsidence, the instability of the protection structure, wave
overtopping and toe erosion as shown in Figure 10.

      instability of protection       wave overtopping           toe erosion

       instability of slope           collision/agression        subsidence

          Figure 10           Various forms of shoreline instability

      The approachable method is to prevent the collapse or
damage or armoured protection by avoiding the structural failure
due to slip circle as shown by ABC in the Figure 11 below.



                                           permeable        DESIGN             sandtight



      Figure 11        Analytical approach of designing revetments
30 / Siri Syarahan Perdana Profesor

The design should encompass the compromise for structural
strength, permeability, filter layer compactness and flexibility
of the system. The various factors that may lead to structural
failure are generalized as shown in the Figure 12.

                                             Structural failure

              Macro instability
                                                                   Erosion of slope

    Micro instability             Instability of protection         Wave overtopping                Aggression

                             Toe erosion                          Subsidence

                        Soil parameters - wave and current conditions - geometry

           Figure 12               Factors contributing to structural failure

        To create a stable beach, wave damping mechanism in the
form of slope protection at the bank or wave reductor nearshore
(artificial reef) can be designed where a balance of structural
strength and load to neutralize the forces is created as illustrated in
the Figure 13 below. The dimensionless stability parameter
H/∆d is evaluated.



                                                              revetment A                  B
                                              wave reductor

                                             H/∆d as mobility parameter                        H/∆d as stability parameter



                 Figure 13                                              α
           Innovative Approaches for Physical Considerations / 31

Case B - Control of Beach Deformation Using Groyne.

A groyne is a structure constructed along a coast usually
sticking out from the normal direction of the shoreline by controlling
longshore sediment transport. This type of structure has been
utilised to prevent coastal regions including river mouths from
both erosion and accretion of sand. The fundamental methodology
to arrest related erosion problems involve as follows.
        A retreat of the shoreline is caused by the longshore gradient
of the total longshore sediment transport. The movement of
the longshore sediment transport can be controlled by constructing
a group of groynes such that the longshore sediment transport may
be reduced. Enclosure of part of the beach from the surrounding
areas by constructing a pair of groynes to make a pocket beach
where the sediment transport rate is closed. A T-type and L-type
groyne are normally constructed for controlling sediment movement
in the cross-shore direction. A pair or group of groynes are
constructed to control longshore movement of replenished
sand through a sand-by passing system.
        The trap rate of the longshore sediment transport rate of a
groyne is a function of the dimensions and plane arrangement of
groynes (length of groynes, spacing, etc.) and the characteristic of
the incident wave and the beach (bottom slope, bed material, etc.).
It is needless to say that the trap rate increases with the increasing
length of the groyne. The function of the groyne where the longshore
sediment transport develop is to tap part of the sediment transported
in the longshore direction to settle it in the upstream of the groynes.
The rest of the sand is transported through the groynes downward.
When the length of the groyne is long enough to trap the whole
longshore sediment transport, severe erosion takes place in the
downstream side of the groyne. The groyne tends to reduce its
function to trap sediment after the amount deposited sand in the
upstream side of it exceeds its capacity.
32 / Siri Syarahan Perdana Profesor

Case C - Artificial Reefs

Measures to preserve sandy beaches using other coastal
structures such as groynes, revetments and offshore breakwaters
often conflict with the criteria needed for tourism which is to sustain
and preserve the natural beauty of the beach. The development of
low crested wide submerged breakwater known as artificial reef is
an alternative that provide protection for the coastline and at the
same time induce marine life. Low crested structures can be divided
into 3 categories; dynamically stable reef breakwaters, statically
stable low-crested breakwaters (exposed) and statically stable
submerged breakwaters.
       Recently, the number of coasts where artificial reefs are
constructed is increasing. The object of the construction is the
reduction of coastal disasters and the effective utilization of the coastal
area by reproducing the function of the natural reef in the sea
naturally. In this system, the width of the breaker zone becomes
wider than that of the native beach and the potential for preventing
disaster increases. The submerged breakwater in the perched
beach-type artificial reef is required to be able to reduce the
energy of high incident waves that may become dangerous
to the beach behind it and to keep replenished sand. Reduction
of wave overtopping by the use of artificial reef (Goda,
1985; CERC, 1984, Sawaragi et al., 1988).
       The artificial reefs are, however, of various shapes, sizes and
materials. They are designed tailored for specific functions
depending on the needs and requirements of the respective
countries. Some are made of an assemblage of used rubber tyres
(Malaysia), branches of plants such as mangrove, bamboo
and coconuts (Philippines), rubblemounds (Indonesia) pre-cast
concrete and PVC (Japan and USA).
       The pre-cast concrete is proposed due to a more systematic
approach in the design of the structure whereby optimum height of
the breakwater can be prepared in accordance to the most efficient
structure to retard the waves or to dissipate the wave energy. “Hex
Reef” and “Restar”, the referred artificial reefs are among those which
have been invented and designed in mind with advantages, and as
           Innovative Approaches for Physical Considerations / 33

a possible alternative for inducing marine life that resembles the
functions of natural reef.

Siltation Studies

Apposing to erosion, there is the sedimentation or siltation phenom-
ena. Siltation is one of the most difficult coastal problems and so too
is the counter measure against sedimentation due to siltation. Sub-
merged breakwaters have been used as protection works against
shoaling in navigation channel at Kumamoto Port (Tsuruya et al.,
1990). COEI has also experienced conducting the physical modeling
studies of siltation by using submerged berms.

Physical Modeling of Coastal Protection Structures

The criterion for a model to replicate the prototype involves several
types of similarity. These include:

Geometric similarity:

For undistorted model, the vertical scale η1 = 1m /1p where 1m and 1p
are the length for model and prototype respectively, and the ratios
for each parts should be the same throughout.

Dynamic similarity:

The forces in the model has to be in the same relative magnitude as
the prototype. For wave models, this normally expressed in the
dimensionless quantity namely Froude Number Fr, i.e

      Fr = [v2 /gd]1/2                                          ...(14)

(Where v is the velocity, g the gravity and d is the water depth). This
Fr must be the same in model and prototype. The physical modeling
of waves follows the assumption that the wavelength is scaled as the
length scale.
34 / Siri Syarahan Perdana Profesor

       Physical models are used because they can simulate
problems we do not fully understand. They actually help us to
understand problems better and point to possible solutions, but the
results are essentially qualitative. The main challenge in
physical modeling is to translate the qualitative results into
useful quantities.
       Other scaling rate of prototype (p) versus model (m) which
are of great concern apart from the length η1 = 1p/1m includes time
ηt = (η1)1/2 e.g., for wave period T, velocity ηv = (η1)1/2 and sediment
size ηd50 = (η1)1/4.
       Scale and laboratory effects will need to be substantially
reduced in the future to make such interpreted physical modeling
results believable. One example of interest to coastal engineers, for
which not all of the coefficients are known and there is
considerable uncertainty about applicable relationships, is
sediment transport by waves and currents, computation of ensuing
morphological changes. Both numerical and physical models of
coastal morphology have major problems. Physical models,
however, even though they are plagued by scale and laboratory
effects, the results will give reasonable qualitative

Key Tasks of Physical Modeling Study

Stage 1: Inception
      Data assembly and familiarization, data review,
      Scoping field investigation and laboratory experiment,
      Site study, confirmation of work and methodology,
      Construction of physical model.

Stage 2: Laboratory testing & simulation tests
     Variable parameters include wave height, current, water
     depth, wave period, model configurations
     Measurement and observations: Reflection, run-up,
     overtopping, settlement, displacement, sediment
     deposition, etc.

Stage 3: Data analysis, evaluation and reporting
           Innovative Approaches for Physical Considerations / 35

Laboratory Facilities at the Coastal and Offshore Engineering
Institute (COEI)

The experiments for the hydraulic model investigations were
possible to be carried out at COEI due to the availability of the state
of the art instrumentation and facilities. These include:
• A wave basin (5 m ∞ 20 ∞ 1 m). Equipped with a computer-
   controlled piston type of wave generator capable of
   generating regular and random waves.
• 4 Fixed bed Test channels/flumes (separate channel for
   sand and mud) fabricated with wave making facilities,
   circulating current, reservoir with agitation tank for mud supply,
   variable slopes and wave absorbers.
• Particle Image Velocimetry (PIV) system using Argon Ion Laser
   and complete image interrogation system.
• Laser-Doppler Velocimetry (LDV): fiber-optic linked system.
• Acoustic Doppler Velocimetry (ADV)system (3-D velocity
• Miniature currentmeters.
• Data acquisition systems and computing facilities.
• Wave sensors, wave probes and wave gauges.
• Suspended sediment monitor (OBS).
• Workshop facilities.

       Velocity measurements and mapping of the flow could
obtained using the Particle Image Velocimetry system (PIV) model
6200 manufactured by TSI Inc., USA. In this experimental set-up, the
laser beam was shot above and parallel to the test flume and then
reflected down from the top by a mirror. It was spread into a light
sheet by the appropriate combinations of cylindrical and spherical
lenses, illuminating a plane parallel to the flow in the flume. A
camera, which was placed alongside the flume, focused the moving
particles through a rotating polygon mirror. The image captured is
analysed by using the interrogation system and PIV software.
Current flow and circulations around structures could be understood
in detail. Studies related to the 3-D flow profiles around structures
could be obtained using the Acoutic Doppler Velocimeter.
36 / Siri Syarahan Perdana Profesor

      Wave measurements using wave sensors and the
acquisition system enables regular and random wave
measurements could be captured instantaneously, N waves
frequently simulated up to 5000 waves.
      The water supply system mainly provides non-saline
water. The availability of workshop facilities, enables COEI to
fabricate its own design structural models for the physical
modeling studies. Technical support staff at COEI and with
the technical support services of counterparts from UK,
Netherlands, India and Singapore as well as local consultants
has enabled comparative research breakthroughs to be
carried out at the Institute. Most of the research conducted
derived support from the government IRPA/RMC 61030, 72096,
72106, 71658 and UTM/COEI for facilities & instrumentations,
whilst others are contract research sponsored by clients
from government agencies and engineering consulting firms.

Physical Modeling Studies: Model Versus Prototype

A brief report on the related research on coastal protection
structures (revetments and breakwaters) carried out at the Coastal
and Offshore Engineering Institute (COEI), Universiti Teknologi
Malaysia (UTM) is presented in this section. Table 4 gives a
summary of the projects.

                                             Table 4
No.             Title of Project                  Sponsor/Client   Year         Status
 1.   Sine-Slab system as coastal                 MOSTE,           Start   Model,
      protection measure                          RMC/UTM          1995    prototype tests
      Scale: 1 : 3, 1 : 5                         DID Melaka               completed
                                                  Zen Concrete     1999    Patented and
      Exhibit size: 1 : 10, 1 : 5, 1 : 3, 1 : 1   Industries Sdn           commercialised
                                                  Bhd, Shah’s              On-going R &
                                                  Beach Resort             D&C,Innovative
 2.   Physical modeling study of                  Jurutera         1994    Hydraulic
      submerged berm for the                      Perunding                Model tests
      proposed harbour at Kuala                   Wahba                    completed
      Baram, Miri, Sarawak
      Scale: 1 : 20
               Innovative Approaches for Physical Considerations / 37

 No.            Title of Project          Sponsor/Client   Year         Status

  3.   Siltation Study and submerged      Public Works     1994    Hydraulic
       berm for Kuala Perlis Jetty        Department               model tests

  4.   Physical modeling study of         Fisheries        1998    Hydraulic
       submerged berm for the             Development              model tests
       proposed fishing harbour at        Authority of             completed
       B a t u M a u n g , Pe n a n g     Malaysia
       Scale: 1 : 15

  5.   Physical modeling study of         National         1995    Hydraulic
       artificial reef (Hex reef) for     Hydraulic                model and
       coastal protection and beach       Research                 prototype tests
       formation at Pulau Layang-Layang   Institute                completed
       Scale: 1 : 20                      (NAHRIM)

  6.   Physical modeling study of Hex     National         1998    Hydraulic
       Reef for the proposed coastal      Hydraulic                model tests
       protection at Terengganu           Research                 completed
       Rivermouth                         Institute
       Scale: 1 : 20                      (NAHRIM)

  7.   Resuspension of suspended          MOSTE,           1997-   Hydraulic
       sediments under breaking wave      COEI,UTM         1998    model tests,
       (Kuala Perlis)                     PhD Thesis               numerical
                                                                   modeling, field

  8.   Siltation problem and              MOSTE            1997    Hydraulic
       submerged berm as                  UTM/RMC                  model tests for
       countermeasure, Scale: 1 : 20      MSC Thesis               various

  9.   Wave propagation over a            UTM/COEI         1999    Hydraulic
       depressed bottom topography        PhD Thesis               model tests,
       Laser-based, Particle Image                                 numerical
       Velocimetry Technique                                       modeling, flow

10*.   Monitoring of south breakwater     Petronas         2002    Field
       at PAB export terminal, Tg.        Research &               observations
       Sulong, Kemaman, Terengganu        Scientific               hydrographic
       with Hydrographic Survey           Services                 survey
       Group, FKSG, UTM                   (PRSS)

11*.   Monitoring restar at Pulau Rhu,    Yayasan Ehsan    2002    Field
       Besut, Terengganu                  Berhad                   /underwaters

12*.   Coastal monitoring and             PRSS             2002    Proposed,
       protection works for Petronas                               awaiting
       Facilities, Terengganu                                      budget

* Recent work carried out while at Bureau of innovation
& Consultancy, UTM.
38 / Siri Syarahan Perdana Profesor


Limitation of the Studies

The reliability of the model simulation tests also rely on the modeling
scale, the limitation on the size of the wave basin or wave flumes will
reduce the accuracy as the size gets smaller. At times it is possible
to perform distorted modeling with varying vertical and
horizontal length scale due to limitation on the size of facilities.
Limited number of models due to cost and constraint on time also
pose a hindrance to obtain a comprehensive data for design
guidelines. The modeling of non-cohesive beach material is not a
trivial process. Many model laws have been derived (Dalrymple,
1985). Problems arise in the scaling of sediments especially as in
the mud case. As sediment becomes significantly smaller, its
properties change (for example, becoming cohesive and this may
not migrate under the action of waves as desired). Due to this
limitation, the sediment samples for the laboratory tests will be larger
than the modeling scale of which d50 should be the fourth power of
the length scale η1. Sediment samples of size below than 0.1 mm is
also difficult to be simulated. In our studies, in order to preserve most
of the properties of sediment, the actual sediment samples collected
from the site as seeding samples was used. This will result in
a mud sample with larger sediment size than that obtained by
simple scaling of d50 by η1 . Reports of other previous studies,
however, have shown that this is the mostfeasible approach.

The following section briefly describes results of some of the
earlier projects undertaken.

Physical Modeling Study of Submerged Berm for the Proposed
Fishing Harbour at Batu Maung, Penang

The Fisheries Development Authority of Malaysia (LKIM) was
concerned about the sedimentation problem in relation to the
proposed infra-structural development at the fishing harbour at
Batu Maung, Penang. The objective of the study was to perform a
              Innovative Approaches for Physical Considerations / 39

physical modeling study for the performance of the proposed
designs of berms in controlling sedimentation. Previous modeling
study by Hydec Engineering Sdn Bhd had suggested to adopt
alternative 2 scheme after modeling using MIKE21 and LITPACK.
This comprised of a northern breakwater (555 m length) constructed
to Mean Sea Level and the Southern breakwater (668 m length)
constructed above the Highest Astronomical Tide. The
typical cross-section of the proposed berm is 2 m and 4 m crest
widths with a slope of 1 : 3, 2 m allowance for side base lengths and
1 m base thickness to allow for settlement. The height of the berm
was then a variable parameter.
       The experimental study was conducted on a 18 meter long
wave flume of cross section 60 cm ∞ 55 cm as shown in Figure 14.
It had flow re-circulating facility through a water tank. A false bed
was constructed with a slope of 1 : 2 in front. A depression was
provided at the end of the bed. A perforated wave damper was
placed at the end of the flume. 1 : 15 scaled model of the proposed
berm was constructed and placed before the depression.
A mechanical stirrer was set into the water tank. The purpose of
placing the stirrer was to stir the water so that sediments are not
settled in the tank.

                                        Wave          generator
                               083 ADV gauge

  In                Pump
        Reservoir                                                 Not to scale

Figure 14       Typical experimental set-up and facilities for berm study
40 / Siri Syarahan Perdana Profesor

Flow was generated using a pump that had a control valve to
regulate the flow. A PC-controlled DC motor oscillated the flap
type wave paddle. The amplitude of the paddle could be adjusted
by changing the shaft position on the motor wheel.
         Based on the requirements of the engineering designs for the
facilities at Batu Maung fishing harbour and the COEI laboratory
facilities, the physical modeling study was conducted in the
laboratory in order to study the effectiveness of the proposed
submerged berm by establishing the current and sediment flow
pattern for variable height to depth (h/d) ratio i.e varying the height h
of the berm at (or the water depth) under corresponding current and
wave condition (including extreme conditions) (Refer to figure 15).
         The factors considered in the design of the mitigative
measures against sedimentation (dredged basin and submerged
berm) in the study area include the Design Water level (DWL), the
design wave characteristics, design water depth, design wave
period and design berm height, sediment transport characteristics,
sediment samples and current range.

                                                     Depression channel
         Stirrer                                     Location of berm
          Data                                        Mud fluid flow


          Figure 15 The test flume showing the set-up of the
          physical modeling study for the submerged berm in
          preventing siltation in a depression channel
            Innovative Approaches for Physical Considerations / 41

  Figure 16   Berm model made of fiber-glass used in the experiment

        Four types of berm configurations were tested and
simulated in the laboratory at a model scale of 1 : 15, one is shown in
Figure 16. The results have shown a tendency for berms with greater
heights to be more efficient. In addition, if the crest width is longer,
more sediments will be settled down and trapped upstream as
the velocity slows down upon reaching the crest and less sediments
deposited downstream due to longer travel time. Variation of
berms efficiency in reducing sediment deposition with relative
berm height were presented. The reduction in sediment deposition
increase linearly with berm height. For lower sediment
concentration, the reduction of deposition increased with h/d
at slower rate initially, but a steep increase in reduction of deposition
occurred when h/d increased above 0.8. With h/d, when sediment
concentration was higher, both of the results show that the
efficiency of the berm was very low when the relative berm height
was low. The efficiency of the berm was reduced when the
sediment concentration was increased. This was because,
over the depression, where the mean velocity was less than
that before the berm, the deposition rate increased with the
sediment concentration. Under relatively less wave-current
action, the increase of sediment concentration enhanced the
flocculation process of the fine cohesive sediment particles.
Flocculated sediments deposited at higher rate with the
increase of the settling velocity.
42 / Siri Syarahan Perdana Profesor

Among the issues arising as limitation of the study include:
(i)     The scaling of sediment properties were simplified in
        terms of its size, salinity and non-saline fluid with no
        flocculating properties.
(ii)    The test was a one-dimensional representation of a purely
        two dimensional scenario and uni-directional wave-current
        was gross simplification of the actual phenomena.
(iii)   Part of the total channel width was taken under consideration
        due to limitation of the space.
(iv)    Seaward open end of the berm was not represented in the
        study and structure was limited laterally by flume walls.
(v)     Waves were considered monochromatic.
(vi)    Bed load transport was not incorporated for the study,
        therefore, interaction of suspended load and bed load was
        not represented.

        By comparison in the efficiency for the reduction of sediment
based on simulated conditions of physical parameters at Batu Maung,
the configuration for berm 4, which have a length of 146.54 cm, height
of 20.00 cm and crest width of 26.6 cm or prototype length of 21.98
m, height of 3 m and crest width of 4 m was recommended. For a
model free board of 7 cm equivalent to prototype free board of 1.05
m, the study has shown that berm 4 will provide about 80 percent
efficiency. On the other hand, if berm 3 was chosen, it may not be as
efficient (η = 65 percent) but it is not economical due to more
material is required to construct for greater height of the berm.
Configuration for model 4 was recommended for a cost effective
solution in this project.

Physical Modeling Study of Artificial Reefs

(a)     (Hex reef) for coastal protection, beach formation and
        enhancement of marine life at Pulau Layang-Layang.
(b)     Other studies on artificial reefs-Restar.

      Sandy beaches of small islands or atolls located on coral
reefs are constantly exposed to wave attacks as well as the
           Innovative Approaches for Physical Considerations / 43

detrimental effects as a result of coastal development boom.
Unwise development of beach resorts and coastal structures often
cause coastal erosion in some areas and sedimentation in
others. Pulau Layang-Layang, the island being named after one
of the species of the sea birds at one time would have become
an irony due to reduction in colony and possible disappearance
of the birds. This was due to the unavailability of beach sand
for nesting, not to mention destruction of hard and soft corals.
Hard structures have been installed around the island to
prevent coastal erosion due to wave attack especially during
seasonal storms. Sedimentation and reduction in water quality
has caused severe effects on the marine habitat.
        Studies related to applications and impacts of introducing
artificial reef i.e., pre-cast concrete structures towards providing
solutions to coastal protection against erosion and as tools for
marine habitat enhancement have been conducted by Malaysian
researchers (Malaysian Dept. of Fisheries, UPMT, NAHRIM,
COEI-UTM). New development in the technology of the construction
of artificial reefs in Malaysia has also introduced the application
of PVC pipes which was launched in 1991 in Kedah (S. Wagiman
et al., 1994 and Kushairi, 1998).
        Terumbu Layang-Layang “Swallow Reef” on Admiralty
charts, is an isolated submerged coral atoll in the South
China Sea, 200 km northeast of Kota Kinabalu, Sabah. Pulau
Layang-Layang           and     Pulau    Tioman     renowned     for
spectacular diving destinations, each has a test bed
designated for pioneer studies and assessment for coral
rehabilitation and enhancement of marine life using specially
designed pre-cast concrete structures.
        The geometrical design is largely determined by the fact
that marine equipment is normally required for construction.
Sometimes, the construction is done with land-based equipment via
a (temporary) causeway, but this approach is not forward as it
requires substantially more material handling. In most cases, the
44 / Siri Syarahan Perdana Profesor

armour of the front face is protected near the bottom by a toe. The
introduction of artificial reef the Hex Reef for the breakwater
is aimed to satisfy design considerations. It has the features of
satisfying the stability criteria (broad base), segmented and
interlocking and made of semi-permeable pre-cast concrete
material (with some spaces in between) that provides an increase
in absorption of wave energy. The specially designed Hex Reef
was aimed at introducing a breakwater that also functions as a
breeding ground for the marine life, (NAHRIM Report, January 1996).
Artificial reef has been found effective in dissipating incoming
wave energy (due to its width) and reduction in wave height in
(NIZAM, 1996). In this study, energy dissipation due to reduction
of wave heights H and variation in velocities U had been
investigated around the model structure, the effects and the
performance evaluated.
        Physical modeling study at model scale of 1 : 20 were
conducted prior to installation of the Hex Reef at Pulau Layang-
Layang (N. Mokhtar et al.). The research described here basically to
provide information on site study and preliminary monitoring results
or baseline study. COEI had constructed a physical model and
performed hydrodynamic tests on the three types of
combinations: combination 1, combination 2 and combination 3.
The study was based on the proposal (NAHRIM, 1996) and
information from Jurutera Perunding Wahba (Semenanjung) and
Jurukur Teguh Sdn. Bhd.
        The following information were obtained at early stage for
design considerations, for example in the case of Pulau Layang-
Layang, the Design Water Level (D.W.L), HAT = 2.2 m on C.D,
MSL = 0.8 m on C.D, LAT = 0 m on C.D. Consequently, a range
of water levels are established in determining wave forces or
impacts on a structure. From hydrographic survey chart, there
appears a large variation in bed topography. Waves also
appear to be non uni-directional but possible impacts of
oblique waves are not considered in this modeling study.
            Innovative Approaches for Physical Considerations / 45

                               (A) The Hex Reef Concept

             Combination 1        Combination 2        Combination 3

     HEX REEF – A Product of NAHRIM

    Figure 17      The concept of artificial Reef namely Reef Hex as coastal
    protection structure with suitable combination types

       Theoretically, it has been reported that in such situations there
would be an increase in littoral sediment transport. The design
concept and implementation is based on the diagrams as shown in
Figure 17.
       In early February 1997, after the physical modeling/laboratory
study was completed, the prototypes were then produced by
Sin Matu Sdn. Bhd. at a casting yard in Limbang, Sarawak. Weight
of each module of Type A = 2000 kg, height: 1200 mm, base 1200
mm, top side: 900 mm with one side slope 4 : 1. The design concept
of a combination of a groyne (80 m) and a detached breakwater
(140 m) was adopted. Artificial reefs, a single side of combination
1 (type A) of Hex Reefs were assembled in the form of a groyne and
a detached breakwater were built at latitude 07 22' 15 N and
longitude 113 50 02' E (Figure 18) to protect the coast and
facilitate beach formation in April 1997. The static stability
parameter NS of Hex Reef for the type A is ~ 2, Characteristic
diameter D =1.2 m, Significant wave height 2 m and relative mass
density ∆1.1. Prototype settings adopted for bed elevation: –5 m,
an equivalent slope: 1.8 m and wave period: 8 seconds. Additional
baseline data collection and biotic monitoring study was conducted
46 / Siri Syarahan Perdana Profesor

    Figure 18   Study location of Hex Reef at Pulau Layang-layang

for the detached breakwater to assess the damage,
colonization and re-growth of the marine life 2–3 months later.
       In the site study, apart from the wave climate, physical
properties of the sea-water and current were also measured for 4
stations (Figure 17). Among the instruments used include wave probe
and recorder, self-recording current meter, Salinity and PH meters.
Of the two breakwaters of prototype A constructed, the groyne
being shorter and well exposed, hence do not appear to have much
impact on marine life. The offshore breakwater being longer with a
greater proportion being submerged, thus some underwater
observations and assessment of living organisms were conducted
using underwater cameras and transect-lines approach respectively.
An increase in the colony of Layang-Layang birds has also been
observed since the completion of the installation of the structures
due to accumulated beach sediments formed for the nesting area.
       The concept of combining the groyne with a detached
breakwater had shown to be successful to trap sediments for the
formation of artificial beach. A single modular row units of Hex Reef
type A was used to stabilize the coast thus prevent further erosion of
the beach which was necessary as a nesting ground
for the seabirds. The study was, however, insufficient as the rate of
accretion or accumulation of sediments need to be estimated and
            Innovative Approaches for Physical Considerations / 47

measured by tracer methods, for example. Since the breakwater were
not submerged or exposed particularly during the low tide, the
effectiveness for marine enhancement tool is reduced. Structures
may be subjected to radically different types of wave
action as the water level at the site varies. The Hex Reef Structure
system provides segmented modules of a breakwater with zoning
of the crest widths into several layers and crevices. The unstability
also have been shown to occur at the edge and bottom of the
structure where greater turbulence and unsteady flow are generated.
This can be minimized by having toe protection as such
other rocks or other vertical structure of heights at least 10–20
percent height of the individual Hex reef module being placed in
front of the structure.
          Field work involving hydraulic study including wave
measurements and visual inspection for the monitoring the
performance of the completed system is required in order to provide
subsequent detailed design of the system or other similar systems
at the particular location around the island or elsewhere. Continuous
monitoring of the performance of the artificial reef systems should
be conducted and with a greater frequency of the data collection
and analysis, a greater understanding for the eco-engineering
solution to restore and conserve the marine environment could be
gathered. Further analysis on the impact of the reef will be carried
out via computer modeling, physical modeling and biotic
monitoring for this year as part of the study phase 2. From the
encouraging laboratory and field results, the Hex Reef has the
potential to be commercialized and applied elsewhere in other parts
of Malaysia and worldwide.
          This pioneer experiment on coral rehabilitation using concrete
structures, however, has showed that coral may grow and multiply
to some extent over a devastated area when given the chance to do
so under oceanographically proper physical conditions created. Ar-
tificial reef and artificial habitat technology, if utilized and implemented
in an acceptable manner, would provide an alternative solution to
counter problems with threatening deterioration of habitat or
depletion in marine resources.
48 / Siri Syarahan Perdana Profesor

Other Artificial Reef Studies - Restar at Pulau Tioman and Pulau

A separate research is undergoing for the application of the Restar
(Restoration of Artificial Reef Structure) and adjacent
area around Manggo Beach, Tekek, Pulau Tioman. Restar is
actually an assemblage of Sine-Slab weighing 2000 kg designed
for loading of marine life of up to 700 kg. This study aims for
coastal protection and the possible affect of diadema on the
settlement of coral larvae. Until that further research is completed,
no appropriate deduction could possibly be made with respect
to this. From the preliminary field results, Restar also has the
potential for creating a habitat for marine life. Another
encouraging observation site for Restar study is at Pulau Rhu,
Besut, Terengganu (Yayasan Ehsan, 2002). Unfortunately,
there was no opportunity for physical modeling study of the
system conducted yet.

Physical Modeling Study of Hex Reef for the Proposed Coastal
Protection at Terengganu Rivermouth

In the case of the problems of blockage encountered at the
Terengganu river-mouth, proposed structures are in the form of
shore-connected pair of groynes using artificial reef structure i.e.,
Hex Reef to control fluid motion (waves and current) resulting in
reduction of wave height and sediment transport NAHRIM, 1998.
The water depth needs to be maintained at certain width of
the channel for traffic at the same time providing calm water
on the leeside of the breakwater. The Hex reef blocks were tested
for various model configurations. Unstability and damage to
structures around the curve of the breakwaters were observed
especially for combination type with high h/d. Accretion were
observed upstream and erosion were detected downstream
of the structure.
       Experimental results were sought for breakwaters installed
at the northern part of the rivermouth, with varying heights of
the structure (combination types) and alignment types. Typical model
           Innovative Approaches for Physical Considerations / 49

cross-sections of breakwaters were fabricated in a two-dimensional
wave channel in the laboratory. The model scale was taken as 1/20.
Model does not include the base material for rubble stones to
represent the rocks for prevention of scour or settlement of the
structure. Three different sea levels were assumed in the present
experiment. H.H.W.L (Highest High Water Level) and L.L.W.L (Low-
est Low Water Level) were considered. Five different wave heights
were employed for the regular tests and two extreme wave heights
were used as contract waves to assess the damage level. The two
contract waves had the significant wave heights as 4.4 m and 5.3 m
respectively. The experiments involve getting the wave
transformation, velocity profiles, sedimentation profiles
(morphological changes) and stability experiments during normal
and extreme conditions.
       The experimentally maximum damage ratios for breakwaters
(straight and cornered alignment) were reasonable, i.e., seaside
damage normally should be less than 5 percent and leeside-side
damage less than 6 percent. Therefore researchers at COEI were
confident that the groyne would be safe within the given hydraulic
tests conditions but special caution has to be prepared i.e., to
provide additional protection in the form of rocks or rubblemound at
the cornered section and edge of the breakwater to prevent scour
and unstability due to overtopping and wave breaking.

The Design and Development of Sine-Slab for Coastal
Protection System: Special Case Study of a Revetment

Sine-Slab ® is a special product of a revetment system
developed by the Coastal and Offshore Engineering Institute under
the IRPA program by funded by MOSTE (Vot. No. 72106, Project No.
03-02-06-0185) and promoted for commercialization by UTM
via Bureau of Innovation and Consultancy and Uni-Technologies
Sdn. Bhd. Based on patent licensing arrangement, the product is
manufactured and marketed by Zen Concrete Industries Sdn. Bhd.
for Malaysia only from February 1998-2003. The Sine-Slab® system
is uniquely designed to work with nature’s forces. It is effectively
50 / Siri Syarahan Perdana Profesor

stable and durable against hydraulic loading, at the same time
being effective in trapping sediment, aesthetic and environment-
friendly. Based on our investigations, the stability coefficient
KD is found to be superior in comparison to the available pre-cast
concrete revetment systems in the market (KD = 40 for Sine-Slab,
compared with reported values of KD = 15.8 for Dolos, KD = 7–20 for
parallel-piped quarry stones, KD = 12 for Tribar). Records of field use
of the system have shown to be effective and enhance the stabilization
of the beach area.

Design Concept and Methods

There exist in the world wide market, as an integrated part of a
coastal protection structure or revetment, pre-cast concrete namely
Armorflex, Flex-slab, Basalton, Channel Lock, Core-Loc, Hydroblock,
Petraflex, Terrafix, A-Jacks, etc. The pre-cast concrete block systems
have received considerable attention in recent years due to their
aesthetic appearance and providing the solution of certain
medium-wave protection problems. The blocks could be laid either
by block-by-block hand placement or by cabled systems that can be
places as large mats. Then industry is becoming competitive and
new products have reached the market.
         The researcher has taken the inventive and innovative steps
to fulfill the objectives to provide a more effective method for erosion
control using pre-cast concrete system—a more stable and durable
barrier to wave action and tidal changes but not a barrier for public
to access the water mark. Its shape is adaptable to the sinusoidal
shape of the waves (hence the name “Sine-Slab” was obtained).
The concrete system is designed to provide sufficient drainage and
pressure relief as it is an environment-friendly method that allows
natural vegetation growth.
         Sine-Slab® (Design No. 2055381, Patent Application No. PI
9504122, DU 2001/) is an articulated pre-cast concrete product
designed to accommodate the forces of nature. It has several unique
features that are not found in other erosion control methods. It can
           Innovative Approaches for Physical Considerations / 51

assure continuous construction and maximum stability via the 4-sided
interlocking units.
       The effective keying means by hook locking system and
slot locking system comprising grooves and flanges that resist
displacement and prevent erosion of the sub-soil (Figure 19).
The sinusoidal shape and perforation pattern of the Sine-Slab
neutralize pressure from changing water levels and absorb energy
from waves, current and turbulent water action. Sine-Slab® has
hollow space structure (void ratio >10 percent) that acts as
canal system to drain away surface water. This provides a natural
buffer to dissipate, disperse energy and impact of loading.

                Female Locking Device
                (Slot Locking System)

      Male Locking Device
      (Hook Locking System)
                                         Female Locking Device
                                         (Hook Locking System)

                              SIDE ELEVATION

             Figure 19        Sine-Slab design concept
52 / Siri Syarahan Perdana Profesor

The trapped sediment would allow vegetation growth and
strengthens the interlocking system further. The concave-
curved or reentrant-faced structure is most effective for reducing
overtopping or run-up thus reducing spray and protects the
crest. The stepped-face wall provides access to the beach area
and reduces scouring of the backwash. Weighing about 50 kg
(600 ∞ 300 ∞ 120 mm) designed for maximum wave height
of 2 m, the high strength concrete (grade 40) is able to distribute
stress and resist elevation movement.
        It is envisaged that other sizes will be produced later to cater
for different site conditions. The prototypes of first version were
produced by a gang-mould of eight. Production rate is between
100 –120 per day. Simple and fast method of laying would shorten
the installation time.

Research Methodology

In view of the economic and environmental factors associated with
coastal protection works, it is considered that the protection
structure carries not only the requirement that the beach is
effectively lined to prevent the possibility of further ingress of
the erosion, but also the system should be so well engineered,
so substantial that it could be clearly expected that the
possibility of catastrophic situations do not exist. Negative
impacts to the nearby areas should be minimised. It is
therefore to be expected that upon completion of the project,
it would be of the highest technical quality and best material
and method available. Thorough research and careful
consideration for proper design is important.

Design Criteria and Governing Hydraulic Parameters

The basic variables of the hydraulic and geo-technical processes
usually appear in various stability formulae, describing
a limit state, e.g. no movement, no displacement or no deformation.
Stochastic variables S, for loading and strength R are
important parameters to determine expected damage of
            Innovative Approaches for Physical Considerations / 53

the structure and consequence maintenance cost. In the
design, appropriate distribution of strength R be must chosen
to obtain the desired reduction of the probability of failure
(or safety) at a given distribution of loading S. the aspects
of the limit of the criteria includes run-up, overtopping and
reflection of waves, armour stability, filter criteria, pressure
relief for geo-technical stability, wave transmission, allowance
for settlement and avoidance of flanking. In the design criteria,
aspects of sliding, uplift and surface resistant are taken into
consideration. The interlocking system in the combination of
tongue and groove mechanism adds to the stability.
        The theory for selection of the product size is based upon
Hudson’s and Meer’s Formula which is a stability formula for armour
units on rubble structures developed by the U.S. Army Waterways
Experiment Station (WES), Mississippi, (CERC,1984). The Hudson’s
formula states that

W50 = (WrHS3 )/KD(Sr –1)3 cot ϕ                                 ...(15)

where Wr     = unit weight (saturated surface dry) of armour unit,
      HS     = Significant wave height,
      Sr     = relative density of armour unit relative to water,
      Sr     = Wr/Ww (Wχ is the unit weight of water),
      W50    = weight of individual armour unit,
      ϕ      = angle of slope measured from the horizontal in
   and KD    = Stability coefficient

that varies primarily with the shape of armour units, roughness of
the armour unit surface, sharpness of the edges and degree of
interlocking obtained in placement, and the number of units
comprising the thickness of the armour layer (revetment). In terms of
stability number NS, it is independent of wave period T and its
relationship with wave height H, KD and slope cot ϕ, it is expressed as

NS = H/{(M/ρ)1/3}∆ = H/∆D50 = (KD cot gϕ)1/3                    ...(16)
54 / Siri Syarahan Perdana Profesor

where H = wave height, M = mass of unit, ρ = density of material, ∆
= submerged relative density = ρ r/ρw–1, D 50 = characteristic
diameter of the unit, KD = Stability coefficient, g = gravity and ϕ =
slope angle.
        Meer’s formula (Van der Meer, 1988) includes the effects of
regular waves and distinguishes between plunging and surging
waves. Besides the wave period and slope angle, other influence on
stability such as duration of storms and the permeability of structure
were also included. The formulae relates the incident wave
conditions and the level of damage that may be allowed to the
dimensionless stability number, H/∆D50. This leads to

H/∆D50 = 6.2 P0.18 (Sd šN) 0.2  ξ m–0.5 for plunging waves     ...(17)
H/∆D50 = 1.0 P–0.13 (Sd š/N) 0.2 šcot α ξ mp for surging waves ...(18)

Where P = notional permeability factor, Sd = damage number = Ac/
D502, N = number of waves,     ξ m = Irribaren number = tan α /Sm1/2
and Sm = 2π HS/gTm2, Tm is the mean wave period.
        In practice, these formulae can give arrange of armour sizes
depending on the choices made in the damage level, Sd. For most
cases, design damage is set at S d = 2 as equivalent to “no
damage”. For slopes smaller than 1 : 2.5, damage may be permitted
to rise, say Sd = 3 – 4 without increasing the overall failure.
        For structural stability, the blocks must be heavy enough to
provide sufficient weight to resist the uplift pressure and wave
forces. However, a heavier block could create a problem of
handling and installation in such instances mechanisation is
necessary. Wave action on a sloping structure will cause the
water surface to oscillate over a vertical range that is generally
greater than theincident wave height. The design run-up level
will be used to determine the level of the structure crest or the upper
limit of protection or as indicator of possible overtopping or
wave transmission. The run-down level will determine the lower
extent of the main armour protection and toe protection. The Shore
Protection Manual (1984) gives values of KD for rough angular
           Innovative Approaches for Physical Considerations / 55

stones as equal to 2.0 for breaking waves and 4.0 for non-breaking
waves. Influences in the stability namely wave height, slope angle,
permeability need to be closely considered. Based on site
conditions of water levels, waves, currents and other environment
factors, initial cross-section can be designed. The detailed design of
the Sine-Slab system involves consideration for the stability of
the cover layer, the security of foundation, the minimization of
settlement and sliding as well as toe protection to prevent
undermining. These call for concern on the slope, crest elevation,
cover layer thickness, filter layer, overtopping, and scour of the toe.
Physical modeling tests for the hydraulic model investigation
were carried out for the Pilot Project (COEI, Pilot Project, May1998,
Technical Seminar, September 1999).

Laboratory Tests

Hydraulic model investigation carried out at COEI (Figure 20) involved
physical modeling study at appropriate scaling for selected
conditions at a site location. Variable conditions for water levels,
wave periods, wave heights and model scale sizes were simulated
in order to obtain relationships of the relevant parameters, that
is wave height Hs, water levels (LAT, MLSW, MLWN, MSL, MHWS
and HAT), wave period-wave steepness Sm, Irribean Number ζm
which is related to the surf similarity parameter (ζm = tan ϕ /HS/Sm)
Coefficient for stability KD and Stability Number NS. Laboratory
tests (Figure) at extreme conditions for highest water level, HAT,
significant wave height HS, and critical wave period of the site
are conducted to check for run-up, stability, failure and settlement.
Hydraulic model tests were carried out in the laboratory at model
scales of 1 : 5 and 1 : 3 and variable parameters, namely wave height,
water level, wave period and slopes (1 : 1, 1 : 2, 1 : 3, and 1 : 5).

Production Tests

Tests at the factory involve the determination of product strength via
compression tests for the female and male interlocking parts. The
56 / Siri Syarahan Perdana Profesor

Figure 20 Hydraulic model investigation for model scaled at 1 : 5 under
wave attack were carried out at various conditions to check on the run-up,
stability and settlement


                  0.9                                  LAT
  Values of R/H

                                                       LAT Condition
                                                       MSL Condition
                  0.7                                  HAT Condition


                        0   0.005   0.01       0.015      0.02         0.025
                                     Values of H/gT2

Figure 21 Simulation tests for stability and run-up were conducted at the
COEI laboratory for guidance in the detail design of prototypes
            Innovative Approaches for Physical Considerations / 57

exercise determines the extent of the requirement of
reinforcement and handling care during transportation. Trial
tests were also conducted for the installation methods by

Field Study

The project setting or the pre-installation procedure includes studies
pertaining to the site condition. The scope of work under the design
and built comprise of land reclamation located at Melaka Tengah
(102° 8' longitude, 2° 14' latitude) comprising 120 m shoreline
fronting Shah’s Beach Resort, south of a heartland, Tanjung Keling.
The area has been identified as a Critical Erosion Area under the
National Coastal Erosion Study (1985). Based on information and
data gathered, the area was undergoing severe erosion due to
changes in the shoreline due to infra-structural development in
the vicinity of the resort. It was retreating more than a meter per year.
Based line data and information are gathered prior to the
construction. These also include the rate of erosion, marine weather,
shoreline geometry survey and hydrographic survey for the profiles
and bathymetry, current, tidal and wave height measurement, grab
sampling as well as the general conditions of the environment
(aspects of social use, accessibility and infra-structure) of the site.

Construction for a Shoreline Protection System - Pilot Study

The construction of marine works is a tricky business. The
contractor does not only exercise his technical know-how, he must
also be intuitive and adaptable to the rough sea conditions and
intelligently working with the tides. It must be emphasized that
executive methods cannot be learned from textbooks but
experience and guidance of experienced senior personnel must
be obtained on the work-site itself. For practical design work,
58 / Siri Syarahan Perdana Profesor

besides the environmental boundary conditions other additional
conditions considered in the design of revetment structures.
These include the stability of the cover layer, the security
of the foundation, the minimization of settlement and sliding and
toe protection to prevent undermining especially during
construction at varying tide levels. The overall design location or
level position of filter layer, toe protection (MLWS), mid-section
of the revetment (MSL) and crest level (HAT) (Refer to Figure 22).


                    CONCRETE WALL                                                        + 2.2m LSD
                                                   + 2.0M         1000

                                                    LSD                          700          + 2.0m LSD
                         2.00                                                                                           SINE - SLAB
                                                                                                                                                                                           HAT   = 1.60

                         1.00                          SAND                                                                                                     GRADE A                    MHWS = 0.90
                                                        FILL         SEAWALL
                                                                                       SAND FILL                                                                                           MSL   = 0.00
                                                                         100mm STONE                               100mm - 150mm Ø    1                                                    MLWN = -0.30

                                                                                                                       STONE              3                                                       -0.50
                                                                         GEOTEXTILE TS 750
                                                                         OR EQUIVALENT                                GEOTEXTILE TS 750 OR EQUIVALENT                                      MLWS = -0.90
                                                                                                                                                                                           LAT   = -1.05



    DATUM R.T. - 4.000
                                                                                                                                                               23.61 .0.40

                                                                                                                                                                             24.65 .0.53
                                                                                                      17.00 0.44
                          9.93 1.72

                                      11.02 1.77



 Scale down at 55 : 1                 AT SHAH MOTEL BEACH FRONT TANJUNG KELING, MELAKA

Figure 22       A typical cross-section of the revetment system constructed
for the Pilot Project

        In the process of constructing the 120 m length of the
Sine-Slab revetment, prior to the installation, systematic planning
are necessary, these include site preparation, toe protection,
earthworks, laying of the geo-textile, filling of gravel layer,
installation of Sine-Slab(r) revetment system, crest and run-up area,
construction of the seawall, earthworks for the beach and
monitoring study.
        Figure 23 shows the chronological events that lead to the
construction of the Pilot Project.
      Innovative Approaches for Physical Considerations / 59

                                                       July 1997

                                                       September 1998

                                                       February 1999

                                                       April 1999

Figure 23   Chronological of events for the Pilot Project
60 / Siri Syarahan Perdana Profesor

Field tests and monitoring work for Sine-Slab revetment
system have been carried out to check on the performance of the
system and to prepare for future design guides. A series of
monitoring program are conducted to check on the system as part
of the post-installation and maintenance procedure. Baseline data
was determined as the comparison reference for future system
performance interpretation and analysis. Initial profile of Sine-Slab
was taken to provide sufficient data for detail quantitative
assessment of the actual behaviour of the structures. To achieve this,
Sine-Slab® system was divided into grid lines at every 10 m interval
and closer grid intervals of 2 unit of Sine-Slab at critical areas to
seaward. The locations as well as the level of grid lines were
determined using the survey equipment and the water-pass.
Continuous monitoring and measurement of parameters are being
carried out for the first one one-year after the completion of the
construction of the revetment. The parameters include tide, wave
and current measurement, settlement, grab sampling, stress and
strain, porepressure and beach profile.
      The system was stable to withstand the wave attacks and
hydraulic loading during the seasonal storms and the highest
astronomical tide experienced for a hundred year’s event (i.e.,
December 4, 1999) as given in Figure 24.
      The walkover surveys from time to time are conducted to check
for overall condition, settlement and change of alignment. This would
enable the researchers to check on changes and performance of
the structural system in detail. Designed to work with nature’s forces,
the product has been found not only preventing further ingress of
the erosion but survey results of beach profiles (three sets of data
taken at four months intervals and 1 2 years later) have shown that
there was a substantial accumulation of sediments trapped by
structures over a period two years in the splash zone as shown in
Figure 25.
         Innovative Approaches for Physical Considerations / 61

Figure 24     The revetment system is stable against the attack of
waves during the extreme storm conditions

Figure 25    Accumulation of sediments as observed in the splash
zone, showing the structural effectiveness in trapping sediments
brought by the waves and tides thus enhancing the stabilization of the
beach area
62 / Siri Syarahan Perdana Profesor

Settlement of the revetment on average in the range of 1–20 mm, the
maximum being at the expected location where the sub-soil is soft
(based on the detailed soil investigation) and at the corners where
the structure units were not locked to each other.
Accumulation of the sediments in the range of 0 mm to 600 mm
thick, the maximum sites being at the toe section, up to about 40
percent of the slope section. Very little settlement and accumulation
were found at the crest area. Marine algae were also observed on
the rocks at the toe where there would be mostly underwater, and at
some places on the rocks, snails, clams and barnacles were also
found. Creepers or sea vegetation has covered some parts of the
revetment system providing the green effect thus softening the look
of the hard concrete structure. Close observations are being
conducted further for signs of structural and physical deterioration
(e.g., corrosion and cracks) as well as potential damage particularly
at the location of expected sub-soil instability and at the cornered
structures or turning angles.
        Visitors to the once lost beach area can now walk on the slabs
and at the same time still get to the water. This is a great advantage
of Sine-Slab® compared to others available in the market. Special
emphasis of the research is given to the overall stability of the
revetment system that comprise of the toe protection, Sine-Slab®
with the filter layer system and the run-up factors. Monitoring
results of the Pilot Project, as well as the first and second
commercial projects are encouraging. Continuous R & D is being
carried out for the design and product improvement to facilitate
production, material composition and durability, economic factors
and environmental outlook. Applications of Sine-Slab® include for
shore protection, land reclamation projects, flood control, ship berths
and docks in harbors, beaches and marinas.

Design and Product Durability Improvement

The research will continue for analyzing and solving other
technicalities involving automatic production, installation and
maintenance (replacement method) as well as for added value
                 Innovative Approaches for Physical Considerations / 63

designs, which are practical and effective to be used for maintenance
of coastal protection structures. Apart from protecting the coastline
from further erosion, the product will in the future be in the market to
provide solution to erosion problem and significantly enhance the
natural or biological features of the coastal and riverside area. New
improved design is needed to facilitate production to meet the
increasing demand, new material composition by introduction of
waste material as partial cement replacement for cost effectiveness
as well as other aspect include product strength and durability
under marine environment, value added options for installation
maintenance and eco-friendliness that will put the product at a
competitive edge.

      Table 4        Features comparison of existing and improved Sine-Slab
No           Features                          Existing Sine-Slab       Improved Sine-Slab

1.     Dimensions (mm)
           i. Prototype Size 1             465 x 325 x 135          650 x 300 x 135
           ii. Prototype Size 2            600 x 300 x 135          1000 x 450 x 200
2.     Interlocking
                                           Full Interlocking        Full Interlocking
            i.    Vertical
            ii.   Horizontal               (Groove & Flange)        (Groove & Flange)
3.     Flexible                            √                        √
4.     Efficient Drainage                  2 Holes                  Single Hole
5.     Sediment Trap                       √                        √
6.     Reinforcement                       √                        √
7.     Structural Strength
       (Compression Test)
                                           5.8 t/f                  To be determined
             i.   Female
                                           9.3 t/f                  To be determined
             ii. Male
8.     Concrete Grade                      Gred 40                  Gred 40
9.     Production Method                   Gang Mould               Press Machine
             i.       Daily Rate           100 pcs / day            720 – 1440 pcs / day
             ii.      Cost Of Production   RM 10                    To be determined
10.    Installation Method                 Manual                   Manual / Machinery
11.    Corner Handling Method              Rigid Slope,             Adjustable Slope
                                           No Interlocking          Semi Interlocking
12.    Maintenance                         Moderate                 Easy
13.    Environment friendly                √                        √

       The new design accommodates interlocking components,
maintenance feature, drainage and sediment trap facility and most
of all enable mass production by compression method. This
consequently will reduce the production cost whilst the unit price
64 / Siri Syarahan Perdana Profesor

can be lowered. Thus the product becomes more value-added,
competitive and attractive to users. The previous 50 kg design
(600 mm ∞ 300 mm ∞ 135 mm) will be replaced with the new design
of 50 kg (650 mm ∞ 300 mm ∞ 135 mm) and 100 kg (1000 mm ∞
450 mm ∞ 200 mm). The 100 kg design will be suitable for East
Coast of Peninsular Malaysia as well as Sabah and Sarawak as
the waves there are much bigger and stronger.

Material Composition

Design of concrete mixes was initially based entirely on compressive
strength. More recently the practice of designing for a definite
flexural strength, indirect tensile strength or for a definite
durability where exposure conditions are severe, has been
developed. In spite of these developments, compressive strength
remains the common criterion of concrete quality. Concrete is
the most widely used and versatile construction material. Therefore,
the durability of this material is of great importance in low
maintenance long-lasting structures. In order to reduce the cost of
production but not to compromise on structural strength, a lower
content of cement i.e, lower grade from 40 to 25–30 is proposed.
Another alternative is to replace cement partially with other material
such as Ground Granulated Blast Furnace Slag from steel waste
(GGBS). Furthermore, concrete made from Portland cement alone
can be vulnerable to attack from sulphates, chloride, acids and
alkali-silica reactions. This is a particular problem in marine, coastal
and other harsh environments, or areas subject to wide temperature
extremes. Replacing a percentage of the cement with GGBS
produces a significantly less permeable concrete with
improved resistance to aggressive conditions. These composite
cements offer workability and strength advantages through lower
water content in the mix and a reduction in early age heat
development. This helps to minimize the possibility of thermal
cracking. Proportions of GGBS may be varied to achieve particular
performance qualities.
        Other optional replacement material is Palm Oil Fuel Ash
(POFA).The usage of (POFA) is also being studied for marine
               Innovative Approaches for Physical Considerations / 65

application. From previous studies done, concrete mix using POFA
is able to reduce bleeding, higher concrete strength at later stage,
provides good workability as well as cost reduction of concrete. The
compressive strength, flexural strength and modulus dynamic of
elasticity of concrete using POFA is yet to be determined.
       For the effort towards prevention of corrosion of reinforcement
wire and structural cracks, a proposal has been drawn to utilise
waterproof concrete using caltite or bio-based material for
structural coating. This will be tested at the Pilot project site.
       The innovation process in the development of Sine-Slab
system is presented as shown in Figure 26 below.

      RESEARCH                          Development of Idea
   Literature survey, Desk studies                                    Secure Funding/ Research Grant
                                           Appointment of
                                         RA/Post Grad student
                                           Team members
         Patent search
         Market study                     Design preparation

       Patent drafting                                                        Patent Application
                                         Model construction
   1995                                                                        Legal document
                                         Laboratory tests

                                     Development of prototypes

                                                                                  Negotiations for
                                                                                  patent licensee

                         Hydraulic model simulation tests for various scales
                                                                                     Signing MOA
                                                                                 Contractual Agreement
 COMMERCIALISATION                                                                     Financing
                               Design confirmation, Prototype production

                                                                                 Identification of
                                                                                 field site for Pilot
                                          Mass production

                                     Construction for Pilot Project

  INNOVATIVE R & D                       Product launching,                     Publications, Exhibitions
  For sustainability 1999                    Marketing

                              Monitoring and product improvement
                                       Design Guidelines

Figure 26      The Innovation process for the development of Sine-Slab system
66 / Siri Syarahan Perdana Profesor


Figure 27 below shows the results of the installation of Sine-Slab
system as Pilot and commercial projects.

      Sine-Slab Revetment System                Construction of prototypes

     Shah’s Beach Resort, Tg. Keling            Butterworth, Penang (540 m)

     Tanjung Keling & Lereh (150 m)             Lereh, Melaka (180 m)

       Tanjung Keling, Melaka                  Tioman Island & Rhu Island

Figure 27    Photos of the Sine-Slab project
           Innovative Approaches for Physical Considerations / 67

       The invention and product development of Sine-Slab has won
several national and international awards including Gold medals
in the 27 th International Exhibition of Inventions in Geneva,
Switzerland (1999) for construction/Civil Engineering Category,
a Special Award from the International Jury for the World Intellectual
Property Organization (WIPO) for best woman inventor and in
the Iranian 13th Khwarizmi International Award (2000). The project
also earned the National Inventors Award (1999) and Gold Medal
for UTM’s University Discovery Award (1999) and Innovation
Award (2000).
       Current research project under IRPA RM 8 undertaken at the
Faculty of Civil Engineering involves the study of economical,
socio-economic impacts climate change due to ENSO events in
       Recent proposed work involves the design and development
of floating breakwater systems using composite material of High
Density PolyEthylene (HDPE). Additives and natural waste fibers
made of rice husk and oil palm fiber are introduced into the polymer
to enhance strength and durability against marine weather
conditions (proposed collaborative work with teams from Faculty
of Chemical Engineering and Chemical Resources, COEI, Marine
Laboratory, Center for Hydrographic Survey, UTM and Petronas
Research & Scientific Services (PRSS).
       Other project in the pipeline is the marine innovation of the
development of artificial reef using ashcrete for recreational and
marine habitat. From reports of 40 countries from six continents, the
application of the habitat technology involving artificial reefs for
multiple use in the fishing industry, management, restoration and
enhancement of resources, releasing of fries, mariculture and catch.
All reports have shown that increase in fish catch achievable in the
range from 20 percent - 4000 percent. The habitats were created for
the effective management of other marine resources and means of
disposing waste products such old boats and tyres.
       Pre-cast concrete systems thus would enhance the supply of
these artificial reefs and specially designed for various purposes to
suit functions, marine requirements and applications for local
environment and conditions. New designs and materials which
68 / Siri Syarahan Perdana Profesor

imitates the tree-like and fan-shape feature of the corals would be
more familiar and pleasing to marine creatures as well as nature’s
lovers. Apart from enriching the marine life and fish resource
enhancement, income from tourism would also boost the nation’s
        Several proposals for the application of Sine-Slab systems as
revetment have been proposed to PSC Naval Dockyard in Lumut,
Kelantan SEDC for Sabak, Bukit Keluang/Pulau Rhu coastal
development project, PETRONAS Kerteh coastline management
project and Terengganu Rivermouth project.
        The challenge ahead for University Technologi Malaysia is to
provide the mechanism for the commercial success of the
innovative product to be implemented primarily to combat the local
erosion problem before actually going for global market.
Continuous backing of R & D results and technical reports of
success stories need to be strengthened. Solutions to meet the
specific requirements of a variety of problems need to be provided.
Additional related design applications for reservoirs and lakes,
hill-slope protection as well as application for artificial reef is underway.
Product and design improvement is targeted at cost effectiveness
and quality for production (automation), installation, maintenance
and product durability as well as product composition and variety.
Competing with other products is one thing, but a sound financial
backing and a dynamic operation of business organisation is
another. Forming strategic alliances (synergising and
strengthening relationships with potential customers), effective
marketing, strong leadership, management and technical experts in
the team are indeed necessary. The uses of K-Economy and
E-Commerce through the internet in the US have revamped the
old-line industry and had actually saved millions of dollars.
The productivity revolution will spread to other parts of the world
due to globalization and future companies will be using the web
technology to boost productivity at every stage of the business
process. Malaysia’s Industrial Master Plan 2 (IMP2) will see the need
to step up R & D (Design), Manufacturing and Marketing to
penetrate global market. Greater emphasis will be given to
R & D and global marketing that involve processes such as
           Innovative Approaches for Physical Considerations / 69

Innovation, Collaboration, Design, Purchasing, Manufacturing,
Logistics, Marketing and Services via the internet.


This paper has highlighted some of the aspects of designing
coastal protection structures and case studies undertaken at the
Coastal & Offshore Engineering Institute (COEI) of UTM.
By realizing the problem and issues related to erosion at the coastal
areas, particularly the high cost of supply, installation and
maintenance of existing structures and failures of some mitigative
measures, a suitably designed pre-cast concrete block is one of
the many options which engineers may find acceptable to use for
coastal protection works. For the product to be acceptable and
used, the R & D phases involve the innovation system that includes
study, design, laboratory simulation, field tests and provision of
design guides from track records of performance as well as
commercialisation phase.
       Physical models are very close to simulations of prototype as
the results of the investigation will give qualitative information.
Physical models are plagued by scale, laboratory effects and high
costs. Physical modeling however, will play a pivotal role between
field observations, which are necessarily spot measurements of
controlled and uncontrolled physical events, and the more-or-less
full understanding of the problem needed for a numerical model. To
mitigate measures to combat the shoreline deformations by
constructing coastal protection structures, the frequent cropped up
questions will be the importance of physical modeling vis a vis to
computer modeling. Numerical models need to be properly
benchmarked, calibrated and verified.
       The cost of modeling can be controlled by using a composite
model approach consisting three distinct phases of physical modeling
phase; The analysis of physical modeling results, and the
computation phase—a complete numerical model, physical
process model results provide appropriate coefficients and transfer
functions. In the case of revetments, physical modeling is sufficient
for detail design of structure, bathymetric data, geo-technical
70 / Siri Syarahan Perdana Profesor

data and other physical data on tides, wave, etc. But for lay out
design, hydrodynamic modeling needs to be performed to ascertain
sediment transport wave refraction and current effects. Engineering
studies need to provide useful answers within a limited time and
budget, for examples, in the case of Hex Reef breakwater projects at
Pulau Layang-layang, Terengganu Rivermouth, submerged berm for
Batu Maung and for Kuala Baram. Research teams need to be
comprised of a cohesive team effort to establish expertise in both
physical and numerical modeling.
       In summary, the general formulation on stability of Sine-Slab®
against wave attack has to be treated as practical formulation for
design purposes. It has been generally acknowledged that block
weight, geometric shape and method of interlocking all play
important roles in the overall system performance breakwaters. The
coefficient of stability KD in the Hudson’s formula could be the choice
of parameter involved to differentiate performance of different
systems. Coastal protection structures based on revetment method
such as Sine-Slab ® may no longer in future be only “hard”
engineering structure, but with added value design, structural
durability, texture and colour of natural sand and vegetated
systems, it will enhance the eco-friendliness and provide
engineering solution that is compatible with nature. Pre-cast
concrete and added value systems can be a good and mostly
cheaper alternative for traditional material/systems. These new
systems deserve to be applied on a larger scale. The newly derived
design methods and stability criteria by taking into
consideration of the stability of the filter layer will be of help in
preparing the preliminary alternative designs with these systems.
However, there are many uncertainties in the design methods.
Therefore, experimental verification and further improvement of
design methods as well as more practical experience at various
loading conditions are needed.
       This paper has presented the innovation experience garnered
through the Sine-Slab project. It is hoped that through practical
experience and continuous R & D, however limited the knowledge
may be, it would be useful to systemise this knowledge and to make
           Innovative Approaches for Physical Considerations / 71

it available to design engineers. The output of the research project
reported has not been confined to laboratory or publications of the
research papers for academic reasons, but the information and
Intellectual Property (IP) created has great potential for
commercialisation in the manufacturing, construction and maritime
industry whilst providing solution to the pertinent problem of soil
erosion. In other words, results of R & D are diffused and technology
being utilized for protecting the environment and benefiting the
society. The experience in undertaking the related research and
management of the technology is beneficial to be extended as
consultancy services for designing planning and management of the
coastal areas from erosion.


The author wishes to thank all the sponsors and clients for
the research and consultancy projects undertaken. For the project
on the development of Sine-Slab, the author wishes to thank Universiti
Teknologi Malaysia (UTM); the Science & Technology Division of
Ministry of Science Technology and the Environment, (MOSTE); Zen
Concrete Industries Sdn Bhd; especially to Zulkipli Hj. Husin and
Zulkifli Ghazali, Aziz Ahmad of Geo-textile (M) Sdn. Bhd.; Ir. Kamal
Hj. Kassim of Jurutera Perunding MSA Sdn. Bhd,; Shah’s Beach
Resort, Dept. of Irrigation and Drainage, Melaka, especially Mokhtar
Abd. Rahim; Utama Permai Sdn. Bhd, and Bustaman & Co. Special
gratitudes and appreciation to participating members particularly
Prof. Hadibah Ismail, Shamsuddin Abd Rahman, Zakaria Ayob,
Md. Halim Mustari, Noor Hanisah Wok, Norazizah Abd. Kadir,
Asrol Wahab, Amran Shukor and the rest of the team in COEI,
Prof. Abd Aziz Ibrahim (former director of COEI); Research
Management Centre and the team especially Abd. Rahman
Shafie, and Assoc. Prof. Azlan Abd. Rahman; Bureau of Innovation
and Consultancy especially to Prof. Dr. Abd. Karim Mirasa,
Assoc. Prof. Hanizam, Norhisham Hamid, Assoc. Prof. Dr. Khalili
Khalil and Taha Othman and Uni-Technologies Sdn. Bhd.,
especially Assoc. Prof. Aziz Md. Amin and Mohd Naim,
Kamal Bani Hashim of Centre for Invention, Technovation
72 / Siri Syarahan Perdana Profesor

Park; Ahmad Shahlan Mardi of Centre for Hydrographic Studies;
Prof. Azmi Abdullah of AutoCad Training Centre, Ismail Salleh
and Siti Norulhana of Media and Graphic Unit UTM, and
the Faculty of Civil Engineering, especially the Dean,
Assoc. Prof. Dr. Ahmad Mahir Maktar and Assoc. Prof. Dr.
Fadhali Zakaria of Universiti Teknologi Malaysia for
their support and contribution in this research project. Special
thanks to my assistants M. Santanam of IIT, Madras, Rahimah
Muhammad, Noor Azura Mohd Bunori, Nasrollah Muhamad,
Zoolhilmi Muhamad, Tuan Aphzan Tuan Mad, and Jasvinder
Singh for their efforts and contributions.

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