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ASSIGNMENT GROUP
KL 3103 Field Data Acquisition and Analysis
Lecturer : Ahmad Mukhlis Firdaus, ST, MT
GROUP 1
Abiba Nurjannah [15513031]
Larasati Devi A [15513016]
Mujaddid Harahap [15513062]
Nelwan Deo Fridolin [15513039]
Siti Nurzannah [15513062]
OCEAN ENGINEERING
FACULTY OF CIVIL AND ENVIRONMENTAL ENGINEERING
INSTITUTE OF TECHNOLOGY BANDUNG
2015
1
Table of Contents
Chapter 1 PREFACE .............................................................................................................................. 3
1.1 Background ............................................................................................................................. 3
1.2 Work Order ............................................................................................................................. 3
Chapter 2 THEORY ............................................................................................................................... 4
2.1 Bathymetry ............................................................................................................................. 4
22..11..11 Nautical Chart ................................................................................................................. 4
2.2 Hydrographic Survey ............................................................................................................... 4
22..22..11 Vertical Depth Measurements ........................................................................................ 5
22..22..22 Datum (WGS84) .............................................................................................................. 6
22..22..33 Transducer and Sensory .................................................................................................. 7
22..22..44 Determine Actual Depth ................................................................................................. 9
22..22..55 Horizontal Position Fixing (Differential GPS method) ................................................... 11
22..22..66 Sounding and Cross Check Line ..................................................................................... 12
2.3 Tidal Theory .......................................................................................................................... 12
22..33..11 Types of tides ................................................................................................................ 13
22..33..22 Tidal Constituents ......................................................................................................... 14
2.4 Theory of ERG Tide ................................................................................................................ 14
2.5 Contour Map ......................................................................................................................... 15
22..55..11 Surfer 9 .......................................................................................................................... 15
22..55..22 Grid Base Map ............................................................................................................... 16
22..55..33 Inverse Distance to a Power ......................................................................................... 16
22..55..44 Kriging ........................................................................................................................... 16
22..55..55 Local Polynomial ........................................................................................................... 17
22..55..66 Minimum Curvature ...................................................................................................... 17
22..55..77 Modified Shepard’s Method ......................................................................................... 17
22..55..88 Moving Average ............................................................................................................ 17
22..55..99 Natural Neighbour ........................................................................................................ 18
22..55..1100 Nearest Neighbour ........................................................................................................ 18
22..55..1111 Polynomial Regression .................................................................................................. 18
22..55..1122 Radial Basis Function ..................................................................................................... 18
22..55..1133 Triangulation with Linear Interpolation ........................................................................ 18
Chapter 3 SURVEY PLANNING ............................................................................................................ 20
2
3.1 Location ................................................................................................................................. 20
3.2 SOUNDING LINE & CROSSCHECK LINE .................................................................................. 21
3.3 Budget ................................................................................................................................... 22
Chapter 4 OUTPUT DATA AND ANALYSIS .......................................................................................... 24
4.1 Tidal Correction ..................................................................................................................... 24
44..11..11 Depth Calibration and Measurement ........................................................................... 24
44..11..22 Transducer correction and Bar Check ........................................................................... 24
4.2 Calculation using ERG Tide .................................................................................................... 25
44..22..11 Inalum Port.................................................................................................................... 25
44..22..22 Tanjung Tiram ............................................................................................................... 28
4.3 AUTOCAD OUTPUT (FIELD DATA) ......................................................................................... 31
4.4 Output Surfer ........................................................................................................................ 32
Chapter 5 CONCLUSION ..................................................................................................................... 34
Table of Figures Figure 1. Bathymetry............................................................................................................................... 4
Figure 2. Echosounder ............................................................................................................................ 5
Figure 3. Advanced Echosounder............................................................................................................ 5
Figure 4. Sounding and Crosscheck Line ................................................................................................. 6
Figure 5. Diagram of a transducer .......................................................................................................... 7
Figure 6. Single Beam Survey .................................................................................................................. 7
Figure 7. Multibeam Survey Design ........................................................................................................ 8
Figure 8. Effect ship motion .................................................................................................................... 8
Figure 9. Reflection plate for bar check correction ................................................................................ 9
Figure 10. Draft and Tides ..................................................................................................................... 10
Figure 11. Vertical Data ......................................................................................................................... 11
Figure 12. DGPS ..................................................................................................................................... 12
Figure 13. Constituents Of Tides ........................................................................................................... 14
Figure 14. Surfer 9 Contouring Program ............................................................................................... 15
Figure 15. Gridding Method .................................................................................................................. 19
Figure 16. Location of Kuala Tanjung .................................................................................................... 20
Figure 17. Sounding and Cross Check Line ............................................................................................ 21
Figure 18. Data Processing .................................................................................................................... 24
Figure 19. Tides Prediction.................................................................................................................... 25
Figure 20. Field Data ............................................................................................................................. 31
Figure 21. Contour Map ........................................................................................................................ 32
Figure 22. Bathymetry of Kuala Tanjung ............................................................................................... 32
Figure 23. Bathymetry of Kuala Tanjung ............................................................................................... 33
Figure 24. Bathymetry of Kuala Tanjung ............................................................................................... 33
Figure 25. Contour Map of Kuala Tanjung ............................................................................................ 34
3
Chapter 1 PREFACE
1.1 Background
Bathymetric survey is a process to get depth data and topography of seabed, include the
objects location which endanger. There are three steps to make bathymetric map, they are
collecting data step, processing data and providing the data (Rismanto, 2011). To obtain
accurate of bathymetric map, needed tidal analysis and bathymetric survey that appropriately
project specification. This is done so that the depth contained in a well-defined bathymetric
map of the MSL or reference area.
Bathymetric mapping is a basic requirement in the provision of spatial information in
planning and activities decision-making about information in the sector of marine.
Bathymetric maps in the application has many benefits in the ocean engineering works,
including the determination of safe shipping lanes, construction planning of coastal structure,
detecting a potential tsunami in an area, and offshore oil mining. Beside of that, bathymetric
map is needed to determine the condition of the morphology of a water area. Bathymetric
map should always be update with changes and developments in these waters, because the
sea conditions are very dynamic.
One of method that is applied to the measurement of the bathymetry by using acoustic
technology seabed. Acoustic seabed have linkages among others in the process of
propagation of sound in water medium which capable to provide basic information about
water, communications and positioning in the waters. One of acoustic technology in
bathymetric mapping is echosounder.
1.2 Work Order
Kuala Tanjung is a feasibility study project, so must not follow IHO standard. But ini this
project is still needed detailed survey, so that maximum distance between sounding line is
500 meters. In this project the longest expected survey will complete in 18 days. Because of
that, this is needed survey design accurately so the result obtained are detail and time frame
for the project are eligible.
This location is done by two groups. This is due to that data that must be processed very
broad, so that the project can divided in two groups. And at this location, there are two points
tide data and sum of data that must be verified are the same.
4
Chapter 2 THEORY
2.1 Bathymetry
Bathymetry is the study of underwater depth of lake or ocean floors. It is the foundation of
the science of hydrography, which measures the physical features of a water
body. Hydrography includes not only bathymetry, but also the shape and features of the
shoreline; the characteristics of tides, currents, and waves; and the physical and chemical
properties of the water itself.
Figure 1. Bathymetry
22..11..11 Nautical Chart
A nautical chart is a graphic representation of a maritime area and adjacent coastal regions. It
displays the charted depth of the water at specific locations with soundings and the use of
bathymetric contour lines. The depth are relative to a “chart datum”. Nautical charts are based
on hydrographic surveys. As surveying is laborious and time-consuming, hydrographic data
for many areas of sea may be dated and not always reliable.
Water depth are measurement in a variety of ways. Historically the sounding line was used.
In modern times, echo sounding is used for measuring the seabed in the open sea. Safe depth
of water should be measured over an entire obstruction, such as a shipwreck.
2.2 Hydrographic Survey
5
Hydrographic Survey is the science of measurement and description of features which affect
maritime navigation, marine construction, dredging, offshore oil exploration/offshore oil
drilling and related activities.
The result from a hydrographic survey are normally plotted to produce a bathymetric contour
map, which is plan of the depth of the sea bed arranged in such a manner as to show lines of
equal depth from the coastline. In a hydrographic survey, the actual measurement of the water
depth is the easy part.
Survey vessels primarily use side scan (single) and multibeam sonar. Sonar (which was
originally an acronym for SOund NAvigation and Ranging) uses sound waves to find and
identify objects in the water and to determine water depth. Some vessels may use single beam
echo sounders.
22..22..11 Vertical Depth Measurements
Figure illustrates the hand-held calibrated lead sounding line, right, and on the left, the simple
engineering echosounder (transducer not shown).
Figure 2. Echosounder
Figure illustrates an advanced echosounder of the type used in modern Class 1 surveys. The
echosounder is linked to a software package and yields electronic contour maps directly. This
type of echosounder is also used for real-time monitoring of dredging works.
Figure 3. Advanced Echosounder
6
Figure 4. Sounding and Crosscheck Line
22..22..22 Datum (WGS84)
GPS reading of the roving antenna are given above a datum called the WGS84 (World
Geodetic System 1984). A cursory look at the topographic and oceanographic details of the
globe indicates that the Earth is a very irregular and complex shape. To map position of those
details, a simpler model of the basic shape of the earth, sometimes called “figure of the
earth”, is required.
The Earth is very nearly spherical. However, it has a tiny equatorial bulge that makes the
radius at the equator about 0.33 percent bigger than the radius at the poles. Therefore, the
simple geometric shape which most closely approximates the shape of the Earth is a biaxial
ellipsoid, which is the three-dimensional figure generated by rotating an ellipse about its
shorter axis. The shorter axis of the ellipsoid approximately coincides with the rotation axis
of the Earth. Because the ellipsoid shape does not fit the Earth perfectly, there are many
different ellipsoids in use, some of which are designed to best-fit the whole Earth and some to
best-fit just one region.
The datum used for GPS positioning is called WGS84. It consists of a three-dimensional
Cartesian coordinate system and an associated ellipsoid, so that WGS84 positions can be
described as either XYZ Cartesian coordinates or latitude, longitude and ellipsoid height
coordinates. The origin of the datum is the geocentric (the center of mass of the Earth) and it
is designed for positioning anywhere on Earth. The WGS84 datum is a set of conventions,
adopted constants and formulae and includes the following items:
The WGS84 Cartesian axes and ellipsoid are geocentric; that is, their origin is
the center of mass of the whole Earth including oceans and atmosphere.
The scale of the axes is that of the local Earth frame.
The orientation of the ellipsoid equator and prime meridian of zero longitude
coincide with the equator and prime meridian of the Bureau Internationale de
l'Heure at the moment in time 1984.0 (that is, midnight on New Year’s Eve
1983).
7
Since 1984, the orientation of the axes and ellipsoid has changed such that the
average motion of the crustal plates relative to the ellipsoid is zero. This
ensures that the Z axis of the WGS84 datum coincides with the International
Reference Pole, and that the prime meridian of the ellipsoid (that is, the plane
containing the Z and X Cartesian axes) coincides with the International
Reference Meridian.
22..22..33 Transducer and Sensory
Figure 5. Diagram of a transducer
A transducer is a device that converts one form of energy to another. Usually a transducer
converts a signal in one form of energy into a signal in another form. A sensor is a transducer
whose purpose is to sense (i.e. detect) some characteristic of its environs.
In bathymetric survey the transducer used is the echo sounder. There is two types of beam
from echo sounders; single beam and multi beam. Multi beam could result in more data and
its effectiveness of the measurement. But in this case the single beam echo sounder is more
feasible because of the water characteristic of Kuala Tanjung as an open seas could risk multi
beam sounding
Single Beam
Figure 6. Single Beam Survey
8
Single beam echosounder produces soundings by transmittingshort pulses of acoustic energy
down toward the seabed and detecting those pulses reflected. The depth under the survey
vessel is then calculated from two way travel time of pulses and the mean speed of sound
over the water column:
Distance = 0.5 x (travel time)x(sound velocity)
By this way a vessel with a single beam echosounder produces lines of soundings, and a map
of contours can be constructed by interpolating the depth values between the survey lines.
Multi Beam
Figure 7. Multibeam Survey Design
Multi beam echosounder maybe considered as a series of single beam echosounders mounted on an
array. Every ping of signa; emitted by transducers (beams) will be equivalent to a fan-shape
transmission which results in the receiving of soundings across the track of the vessel.
Figure 8. Effect ship motion
9
It is easily conceived that the accuracy of sounding using multi beam echosounder will
deteriorate from the beam at nadir to the outer side beams because of the dynamic movement
of the vessel. The most significant effect is due to the movement in roll, pitch and heave.
Effect of roll, the roll rotation will cause lateral displacement of whole swath. This will cause
a tilting of seabed as well as smaller guaranteed surveyed coverage. The vertical error it
produces is also considered to be most significant one in multi beam hydrographic survey.
Effect of pitch, this will displace the sounding forward or aft by the tangent of the pitch angle
and thus causes horizontal error.
Effect of heave, heave altrs the instantaneous elevatiom of the transducer with respect to the
seabed and directly produces a vertical eror of the same magnitude onto the sounding.
22..22..44 Determine Actual Depth
The depth calibration is needed to determine the actual depth from the measured data.
These are the depth calibrations needed to perform and calculate:
Transducer Correction
In bathymetric survey the transducer used is the echo sounder. There is two types of beam
from echo sounders; single beam and multi beam. Multi beam could result in more data and
its effectiveness of the measurement. But in this case the single beam echo sounder is more
feasible because of the water characteristic of Kuala Tanjung as an open seas could risk multi
beam sounding
The transducer position is submerged in the water. Therefore, the actual depth can be
determined from the measured depth from the single beam echo sounder added by the echo
sounder depth.
Figure 9. Reflection plate for bar check correction
10
Bar Check Correction
The bar check method will be performed by the surveyor prior to gathering data. An air filled
metal bar lowered below the transducer, attached at each end by a rope marked with depth
values. The values on the rope can be assumed to be correct, and the bar is lowered at set
depth intervals and observed on the echo sounder trace. The values of echo sounder depth can
be plotted against the true depth of the bar. Any fixed offset value would then be attributed to
a draft value correction, and any gradient change seen is as a result of a difference in sound
velocity. Reflection plate is used when calculating sound velocity correction value by the bar
check method.
Draft and Tides
The survey vessel’position is effected by the water surface level. Its draft height and the
water eventual tide level also contributed to the actual depth. If the draft level has ben
implemented into overall transducer depth, the measured depth will only needed to be added
by transducer correction, then reduced by bar check correction, and tide level.
Figure 10. Draft and Tides
11
Figure 11. Vertical Data
22..22..55 Horizontal Position Fixing (Differential GPS method)
There are some method to measure horizontal position, they are parallel line method, the ray
method, and Differential GPS method.
Differential GPS is the primary survey reference for all types of present-day engineering and
construction activities. GPS is a continuous, all-weather, worldwide, satellite-based electronic
positioning system. It is available to the general public and is known as a standard positioning
service. Over the past several years, a technique has been developed to process signals from
two GPS receivers operating simultaneously to determine the 3-D line vector between the
two receivers. This technique is known as “differential positioning” (DGPS) and can produce
real-time positions of a moving vessel.
12
Figure 12. DGPS
22..22..66 Sounding and Cross Check Line
Sounding line is a weighted line with distances marked off at regular intervals, used to
measure the depth of water under a boat. Cross check line is a weighted line to cross check
the depth of water under a boat.
2.3 Tidal Theory
Tides are the rise and fall of sea levels caused by the combined effects of gravitational forces
exerted by the Moon, Sun, and rotation of the Earth. Tides can either help or hinder a
mariner. A high tide may provide enough depth for a ship to pass through certain area, while
a low tide may caused the depth decreasing and might be a problem for mariner to pass his
ship. Therefore, the mariner should have at least one tidal data prediction at the location
where the ship will go. So the mariner could know the variation of depths of the water and
use it as a reference so the ship could have a safe sailing. Accurate analysis and forecasting of
tidal level are very important tasks for human activities in oceanic and coastal areas. They
can be crucial in catastrophic situations like occurrences of Tsunamis in order to provide a
rapid alerting to the human population involved and to save lives.
There are some methods to predicts the sea water levels due to the tidal analysis. Some of
them are Least Square Analysis, Nao Tide Modelling, ERG Tide Modelling, and Admiralty
Analysis. The method will process the input data of tide level each day from the begining to
13
the end of the day for fifteen days. Then, the data will computerized to predict the level of
the tides for 18.6 years. The output data this method can be useful for the mariner to
determined the best time to sail.
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational
forces exerted by the Moon and the Sun and the rotation of the Earth. Most places in the
ocean usually experience two high tides and two low tides each day (semi-diurnal tide), but
some locations experience only one high and one low tide each day (diurnal tide). The times
and amplitude of the tides at the coast are influenced by the alignment of the Sun and Moon,
by the pattern of tides in the deep ocean and by the shape of the coastline and near- shore
bathymetry. The elevation of the sea water changing everytime because of the movement,
variaation of location, and the gravity effects between the Moon, Sun, and the Earth.
The principal tidal forces are generated by the Moon and Sun. The Moon is the main tide-
generating body. Due to its greater distance, the Sun’s effect is only 46 percent of the
Moon’s. Observed tides will differ considerably from the tides predicted by equilibrium
theory since size, depth, and configuration of the basin or waterway, friction, land masses,
inertia of water masses, Coriolis acceleration, and other factors are neglected in this theory.
Nevertheless, equilibrium theory is sufficient to describe the magnitude and distribution of
the main tide-generating forces across the surface of the Earth. Newton’s universal law of
gravitation governs both the orbits of celestial bodies and the tide-generating forces which
occur on them. The force of gravitational attraction between any two masses, m1 and m2 is
given by:
Where d is the distance between the two masses, and G is a constant which depends upon the
units employed. This law assumes that m1 and m2 are point masses. Newton was able to
show that homogeneous spheres could be treated as point masses when determining their
orbits.
22..33..11 Types of tides
Tide changes proceed via the following stages: a. Sea level rises over several hours, covering
the intertidal zone; flood tide. b. The water rises to its highest level, reaching high tide. c.
Sea level falls over several hours, revealing the intertidal zone; ebb tide. d. The water stops
falling, reaching low tide.
Tides produce oscillating currents known as tidal streams. The moment that the tidal current
ceases is called slack water or slack tide. The tide then reverses direction and is said to be
turning. Slack water usually occurs near high water and low water. But there are locations
where the moments of slack tide differ significantly from those of high and low water.
14
Tides are commonly semi-diurnal (two high waters and two low waters each day), or diurnal
(one tidal cycle per day). The two high waters on a given day are typically not the same
height (the daily inequality); these are the higher
high water and the lower high water in tide tables. Similarly, the two low waters each day are
the higher low water and the lower low water. The daily inequality is not consistent and is
generally small when the Moon is over the equator.
22..33..22 Tidal Constituents
Tidal constituents are the net result of multiple influences impacting tidal changes over
certain periods of time. Primary constituents include the Earth's rotation, the position of the
Moon and Sun relative to the Earth, the Moon's altitude (elevation) above the Earth's equator,
and bathymetry. Variations with periods of less than half a day are called harmonic
constituents. Conversely, cycles of days, months, or years are referred to as long period
constituents.
Tidal constituents has amplitudes and phases. These value determines the level of the tides
with vary combinations of each constituent.
Figure 13. Constituents Of Tides
2.4 Theory of ERG Tide
ERG-tide is a program which was made by an Ocean Engineer from Institut Teknologi
Bandung. This program allows us to input the tidal data for several days and calculate it to
predicts the tidal data for ocean. It can measure amplitudes of tidal components and their
own phases, predict the sea levels, and determine the important elevation such as MSL,
HHWL, LLWL, etc. ERG Tide is basically a Least Square Program.
15
2.5 Contour Map
The results from a hydrographic survey are normally plotted to produce a bathymetric
contour map, which is a plan of the depth of the sea bed arranged in such a manner as to
show lines of equal depth from the coastline. In this assignment, we use Surfer 9 to do the
contour mapping.
22..55..11 Surfer 9
Surfer is a full-function contouring and surface modeling package that runs under Microsoft
Windows. Surfer is used extensively for terrain modeling, bathymetric modeling, landscape
visualization, surface analysis, contour mapping, watershed and 3D surface mapping,
gridding, viewshed analysis, volumetrics, and much more.
Figure 14. Surfer 9 Contouring Program
Surfer’s sophisticated interpolation engine transforms XYZ data into publication-quality
maps. Surfer provides more gridding methods and more control over gridding parameters,
including customized variograms, than any other software package on the market. It also use
grid files obtained from other sources, such as USGS DEM files or ESRI grid files. Display
grid as outstanding contour, 3D surface, 3D wireframe, watershed, vector, image, shaded
relief, and viewshed maps. Add base maps to show boundaries and imagery, post maps to
show point locations, and combine map types to create the most informative display possible.
Virtually all aspects of maps can be customized.
16
22..55..22 Grid Base Map
The most common application of Surfer is to create grid-based maps from XYZ data files;
these include contour maps, image maps, shaded relief maps, vector maps, surfaces and
wireframes. XYZ based source data typically comprises of irregularly spaced values and as
such cannot be used directly to generate a grid-based map. Consequently, the source data
must be converted into an evenly spaced grid of data values which may in turn be mapped.
The gridding process effectively extrapolates or interpolates data values at locations where
data values are absent. There are a variety of alternative methods which may be utilised to
complete the gridding process; naturally, the resultant grid files produced via each method
will inherently be different. An overview of the gridding methods available are outlined
below. In addition, each gridding method has been applied to a single source data set
consisting of 47 values (Graphic - Centre Plot); the resultant processed grid files are
presented as a series of contour maps (Graphic – Satellite Plot 1 to 11) radiating from the
central source. The aim is to provide a visual overview and comparison of the gridding
methods.
22..55..33 Inverse Distance to a Power
The Inverse Distance to a Power gridding method is a weighted average interpolator, and can
be either an exact or a smoothing interpolator. With Inverse Distance to a Power, data is
weighted during interpolation such that the influence of one point relative to another declines
with distance from the grid node. Weighting is assigned to data through the use of a
weighting power that controls how the weighting factors drop off as distance from a grid
node increases. The greater the weighting power, the less effect points far from the grid node
have during interpolation. As the power increases, the grid node value approaches the value
of the nearest point. For a smaller power, the weights are more evenly distributed among the
neighbouring data points. One of the characteristics of Inverse Distance to a Power is the
generation of ‘bull's-eyes’ surrounding the position of observations within the gridded area.
However, a smoothing parameter may be applied during interpolation in order to reduce the
‘bull's-eye’ effect. The method does not extrapolate elevation values beyond those found in
the source data (Graphic - Satellite Plot 1).
22..55..44 Kriging
Kriging is a geostatistical gridding method which attempts to express trends suggested within
the source data; for example, high points might be connected to form a ridge rather than
being represented as isolated peaks. Kriging is a very flexible gridding method whereby the
default parameters may be accepted to produce an accurate grid of the source data;
alternatively, Kriging can be custom-fit to a data set by specifying an appropriate variogram
model. Kriging can be either an exact or a smoothing interpolator depending on the user-
specified parameters. The method may extrapolate elevation values beyond the limits found
in the source data (Graphic – Satellite Plot 2).
17
22..55..55 Local Polynomial
The Local Polynomial gridding method assigns values to grid nodes by using a weighted least
squares fit with data within the grid node's search ellipse. The method is most applicable to
data sets that are locally smooth (Graphic – Satellite Plot 3).
22..55..66 Minimum Curvature
The interpolated surface generated by Minimum Curvature is analogous to a thin, linearly
elastic plate passing through each of the data values with a minimum amount of bending.
Minimum Curvature generates the smoothest possible surface while attempting to honor
source data as closely as possible. However, Minimum Curvature is not an exact interpolator
consequently source data is not always honored exactly. Minimum Curvature produces a grid
by repeatedly applying an equation over the grid in an attempt to smooth the grid; each pass
over the grid is counted as a single iteration. The grid node values are recalculated until
successive changes in the values are less than the Maximum Residuals value, or the
maximum number of iterations is reached. The method may extrapolate elevation values
beyond the limits found in the source data (Graphic – Satellite Plot 4).
22..55..77 Modified Shepard’s Method
The Modified Shepard's Method uses an inverse distance weighted least squares method. As
such, Modified Shepard's Method is similar to the Inverse Distance to a Power interpolator,
but the use of local least squares eliminates or reduces the ‘bull's-eye’ appearance of the
generated contours. Modified Shepard's Method can be either an exact or a smoothing
interpolator. Initially, the Modified Shepard's Method computes a local least squares fit of a
quadratic surface around each observation. The Quadratic Neighbours parameter specifies the
size of the local neighbourhood by specifying the number of local neighbours. The local
neighbourhood is a circle of sufficient radius to include exactly this many neighbours. The
interpolated values are generated using a distance-weighted average of the previously
computed quadratic fits associated with neighbouring observations. The Weighting
Neighbours parameter specifies the size of the local neighbourhood by specifying the number
of local neighbours. The local neighbourhood is a circle of sufficient radius to include exactly
this many neighbours. The method may extrapolate elevation values beyond the limits found
in the source data (Graphic – Satellite Plot 5).
22..55..88 Moving Average
The Moving Average gridding method assigns values to grid nodes by averaging the data
within the grid node's search ellipse. For each grid node, the neighbouring data is identified
by centring the search ellipse on the node. The output grid node value is set equal to the
arithmetic average of the identified neighbouring data. If there are fewer than the specified
minimum numbers of data within the neighbourhood, the grid node is blanked. The moving
average is most applicable to large and very large data sets; for example, >1000 data points. It
extracts intermediate scale trends and variations from large noisy data sets. This gridding
method may be used as an alternative to Nearest Neighbour for generating grids from large,
regularly spaced data sets (Graphic – Satellite Plot 6).
18
22..55..99 Natural Neighbour
What is Natural Neighbour interpolation? Consider a set of Thiessen polygons, if a new point
(target) were added to the data set, the Thiessen polygons would be modified. In fact, some of
the polygons would shrink in size, while none would increase in size. The area associated
with the target's Thiessen polygon that was taken from an existing polygon is called the
‘borrowed area’. The Natural Neighbour interpolation algorithm uses a weighted average of
the neighbouring observations, where the weights are proportional to the ‘borrowed’ area.
The Natural Neighbour method does not extrapolate contours beyond the convex hull of the
data locations. The gridding method uses a weighted average of the neighbouring
observations and generates good contours from data sets containing dense data in some areas
and sparse data in other areas. The method does not extrapolate elevation values beyond
those found in the source data (Graphic – Satellite Plot 7).
22..55..1100 Nearest Neighbour
The Nearest Neighbour gridding method assigns the value of the nearest point to each grid
node. This method is useful when data is already evenly spaced. Alternatively, in cases where
the data points are nearly on a grid with only a few missing values, this method is effective
for filling in the holes in the data. The method does not extrapolate elevation values beyond
those found in the source data (Graphic – Satellite Plot 8).
22..55..1111 Polynomial Regression
Polynomial Regression is used to define large-scale trends and patterns in source data.
Polynomial Regression is not really an interpolator because it does not attempt to predict
unknown elevation values. There are several options which may be used to define the type of
trend surface. The method may extrapolate elevation values beyond the limits found in the
source data (Graphic – Satellite Plot 9).
22..55..1122 Radial Basis Function
Radial Basis Function interpolation is a diverse group of data interpolation methods. In terms
of the ability to fit source data and to produce a smooth surface, the Multi-quadric method is
considered by many to be the best. All of the Radial Basis Function methods are exact
interpolators, so they attempt to honor the source data. In addition, a smoothing factor may be
applied in an attempt to produce a smoother surface (Graphic – Satellite Plot 10).
22..55..1133 Triangulation with Linear Interpolation
The Triangulation with Linear Interpolation method utilises Delaunay triangulation. The
algorithm creates triangles by drawing lines between data points; the original points are
connected in such a way that no triangle edges are intersected by other triangles. The result is
a patchwork of triangular faces over the extent of the grid. Each triangle defines a plane over
the grid nodes lying within the triangle, with the tilt and elevation of the triangle determined
by the three original data points defining the triangle. All grid nodes within a given triangle
are defined by the triangular surface. Because the original data is used to define the triangles,
the data is honored very closely. Triangulation with Linear Interpolation is most effective
when the source data is evenly distributed over the grid area, therefore data sets that contain
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sparse areas result in distinct triangular facets on the map. The method tends to produce
angular contours for small data sets. The method does not extrapolate elevation values
beyond those found in the source data (Graphic – Satellite Plot 11).
Figure 15. Gridding Method
In this assignment, we use the Kringing Method because Kriging is a very flexible gridding
method. It is easy to accept the kriging defaults to produce an accurate grid of the data, or
kriging can be custom-fit to a data set by specifying the appropriate variogram model.
Within Surfer, kriging can be either an exact or a smoothing interpolator depending on the
user-specified parameters. It incorporates anisotropy and underlying trends in an efficient
and natural manner.
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Chapter 3 SURVEY PLANNING
3.1 Location
Figure 16. Location of Kuala Tanjung
The Kuala Tanjung bathimemtri survey will be located in Kuala Tanjung, Kecamatan Batu
Seisuka, Kabupaten Batu Bata, North Sumatera, Indonesia. Kuala Tanjung is located on the
Latitude 3°22” N and Longitude 99°26’E. From the station, tidal data will be obtained
which then will be processed together with the bathymetric survey results.
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3.2 SOUNDING LINE & CROSSCHECK LINE
Figure 17. Sounding and Cross Check Line
We use AUTOCAD to draw the sounding line and the crosscheck line plan. The interval
between the sounding lines is 500 meters. After being calculated by the measuring tool in
ATUTOCAD, we get the total length for the sounding line is 391998 meter, and the total
length for the crosscheck line is 110862 meters.
The bathymetric survey conducted specified on the survey area below
sounding line
length = 391998 m
cross check length = 110862 m
total length = 502860 m
.
The speed
of survey
vessel
= 3 knot
= 5556 m/hour
From the data upside, we measure the duration of the survey required.
,
and now we got the duration of the survey required is about 90.5075594 hours.
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With the estimated working hour which is 7 hours/day, the bathymetric survey will run by 1
vessel and will take 13 days long.
3.3 Budget
Data unit costs are based on prices on the island of Java. For other locations following the
multiplication below
Location Factor Item
Sumatra 1.1 Accommodation and rental vessel
Price LS intention is Lump Sum (where the price remained unchanged with time jobs)
NO Description Unit
Unit
Rate
(Rp)
Amount Price (Rp)
Man/Unit Day
A Expert and Support
1 Team Leader Man Day 1,500,000 1 12 18,000,000
2 Operator Sub
Bottom Profiling Man Day 1,000,000 2 12 24,000,000
5 Surveyor Man Day 750,000 4 12 36,000,000
Sub Total 78,000,000
B Vessel Rental Unit Day 2,500,000 1 13 32,500,000
Sub Total 32,500,000
C Rental Equipment and Materials
1 Echo Sounder Unit Day 1,500,000 2 12 36,000,000
3 DGPS Unit Day 1,500,000 2 12 36,000,000
9 Aki LS 700,000 2 1 1,400,000
10 Genset LS 3,500,000 2 1 7,000,000
Sub Total 80,400,000
D Lodging and Accommodations
1 Room Rental
Lodging Day 300,000 2 12 7,920,000
2 Daily
accommodation Day 1,500,000 1 12 19,800,000
3 Rental Car + Fuel LS 1,000,000 1 1 1,100,000
Sub Total 28,820,000
Total 1 219,720,000
overhead 10% 21,972,000.00
contingency 5% 10,986,000.00
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Total 2 252,678,000
profit 10% 25,267,800
Total 3 277,945,800
tax 10% 27,794,580
Total Project Budget 305,740,380
The total budget we need to do this survey is Rp 305,740,380.00
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Chapter 4 OUTPUT DATA AND ANALYSIS
4.1 Tidal Correction
Figure 18. Data Processing
44..11..11 Depth Calibration and Measurement
Bathymetry Survey results obtained two pieces of data depth, the depth measurement and depth calibration. In data processing, which is used is the depth calibration. Depth calibration is the result of the depth measurement reference point against transducer been calibrated against the surface of the water. This is necessary due to the implementation of the sea, the elevation of the vessel will be affected by the ocean waves. So as to obtain accurate data required calibration beforehand.
44..11..22 Transducer correction and Bar Check
In the measurement of hydrographic surveys, the transducer is placed a few meters below the surface of the water, so the water depth measurement obtained is the distance from the face of the transducer to the seabed. So that the necessary corrections to the transducer whose value has been given to the hydrographic survey report.
In addition to the correction transducer, there is also a correction bar check. Bar check correction is a correction of the tools used. Bar check correction value is the value of error or an error during tool measurement.
During the survey was conducted, the results of measurements obtained still needs to be corrected against the tides. It is because the echo sounder measurement is affected outcomes distance from the transducer surface to the ocean floor. And this depth of data is influenced by tidal activity is happening so that at any time in the depths of a point can change depending on the value of the tides is going on.
To obtain the data correction tides, need to do interpolate the data to the data tides with 30-minute intervals that have been given. Interpolation is done to obtain data on water level every second. the result of interpolation conducted on the figure.
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Figure 19. Tides Prediction
Tide correction made to two references. References to LWS in the area INALUM and
Tanjung Tiram.
The selected reference is Lowest Water Spring (LWS) due to the construction of ports, it
takes a minimum elevation data that can be specified waters ship cruise lines right.
4.2 Calculation using ERG Tide
We calculate the important elevations in two places, Inalum Port and Tanjung Tiram.
44..22..11 Inalum Port
(i) First input
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The first input is the elevation data from the field for 15 days from Inalum Port. The starting
date is from July 2006. This data will be the input for the ‘ERGTIDE.exe’ program.
(ii) ERGTIDE Output
After we run the ‘ERGTIDE.exe’, we get the amplitude and the phase differences of each
constituents for Inalum Port. And then, these data were transposed to be the second input to
the next program.
(iii) Second Input
This is the result of the transposed data, and will be the input of the ‘ERGRAM.exe’
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(iv) ERGRAM Output
The ‘ERGRAM.exe’ output is the prediction of the elevation that we input for the range of
7305 days, starting from the data that we input (from July 2006).
(v) ERGELV Output
This is the final output for Inalum Port. It contains the important elevations that shown above.
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44..22..22 Tanjung Tiram
(i) First Input
The first input is the elevation data from the field for 15 days from Tanjung Tiram. The
starting date is from 30th
September 2014. This data will be the input for the ‘ERGTIDE.exe’
program.
(ii) ERGTIDE Output
29
After we run the ‘ERGTIDE.exe’, we get the amplitude and the phase differences of each
constituents from Tanjung Tiram. And then, these data were transposed to be the second
input to the next program.
(iii) Second Input
This is the result of the transposed data, and will be the input of the ‘ERGRAM.exe’
(iv) ERGRAM Output
The ‘ERGRAM.exe’ output is the prediction of the elevation that we input for the range of
7305 days, starting from the data that we input (from 30th
September 2014).
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(v) ERGELV Output
This is the final output for Tanjung Tiram. It contains the important elevations that shown
above.
Sounding Line conducted on October 1 to October 8 2014 corrected for LWS INALUM
(15,15 cm). Survey on 9 October to 16 October 2014 corrected for LWS Tanjung Tiram
(66.97 cm).
LPS benchmark obtained using tide ERG program. ERG tide been in error is small, easy to
use, and does not need correction against the GMT time.
This program is a data input water level at intervals of 30 minutes for 16 days. The output of
this program is the elevation - elevation is important as follows.
From the tidal correction we will get Z data whit formula follow,
Z = corrected depth
DC = depth calibration
KT = Transducer correction
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KB = bar check correction
KP = tidal correction
LWS = low water spring
4.3 AUTOCAD OUTPUT (FIELD DATA)
Figure 20. Field Data
The sounding line and crosscheck line from the field data created different paths form the
plan because of the depth of the survey area that is too shallow for the ship to sail across. The
second cause, there is an area that is full with ‘sero’. ‘Sero’ is an arrangement of fence that
meant to guide the fishes into the trap made by the fisherman.
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4.4 Output Surfer
This is the 2D contour map.
Figure 21. Contour Map
These are the bathymetry of Tanjung Kuala in many views.
Figure 22. Bathymetry of Kuala Tanjung
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Figure 23. Bathymetry of Kuala Tanjung
Figure 24. Bathymetry of Kuala Tanjung
The bathymetry of Kuala Tanjung has a ocean trenches with maximum depth is 21m below
sea water level.
34
Chapter 5 CONCLUSION
The bathymetric survey on the designated location of Kuala Tanjung need twelve work days
with one survey vessels for the most effective way. The survey team consists of a team
leader, two sub bottom profelling operators, and four surveyors. The total cost including
accomodation and tools is Rp 305,740,380.00
The bathymetric survey produces the contour map as shown below.
Figure 25. Contour Map of Kuala Tanjung
The maximum depth of the maps is 21m.
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APPENDIX
—————————— Gridding Report
——————————
Data Source Source Data File Name: C:\Users\nelwan\Desktop\backup pen\padl2\fixxx.dat X Column: A Y Column: B Z Column: C
Data Counts Active Data: 62705 Original Data: 62707 Excluded Data: 0 Deleted Duplicates: 2 Retained Duplicates: 2 Artificial Data: 0 Superseded Data: 0
Univariate Statistics ———————————————————————————————————————————— X Y Z ———————————————————————————————————————————— Minimum: 552092 356229 -47.2 25%-tile: 559873 361694 -9 Median: 562792 364450 -6.1 75%-tile: 565788 367191 -2.7 Maximum: 572028 372476 -0.4 Midrange: 562060 364352.5 -23.8 Range: 19936 16247 46.8 Interquartile Range: 5915 5497 6.3 Median Abs. Deviation: 2960 2749 3.3 Mean: 562904.85050634 364450.77180448 -6.5849501634637 Trim Mean (10%): 562886.03623638 364455.78724196 -6.2324532648183 Standard Deviation: 3856.7047925482 3569.0139555361 4.68194932791 Variance: 14874171.856864 12737860.614812 21.920649509117 Coef. of Variation: -1 Coef. of Skewness: -0.99939760219586 ————————————————————————————————————————————
Inter-Variable Correlation
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———————————————————————————— X Y Z ———————————————————————————— X: 1.000 -0.450 0.086 Y: 1.000 -0.644 Z: 1.000 ————————————————————————————
Inter-Variable Covariance ———————————————————————————————— X Y Z ———————————————————————————————— X: 14874171.856864 -6192563.7349669 1552.8858253276 Y: 12737860.614812 -10764.059634031 Z: 21.920649509117 ————————————————————————————————
Planar Regression: Z = AX+BY+C Fitted Parameters ———————————————————————————————————————————— A B C ———————————————————————————————————————————— Parameter Value: -0.00031020067383353 -0.00099584988072164 530.96677139867 Standard Error: 3.9630274726521E-006 4.2824788852995E-006 3.2473731432181 ———————————————————————————————————————————— Inter-Parameter Correlations ———————————————————————————— A B C ———————————————————————————— A: 1.000 -0.450 -0.903 B: 1.000 0.790 C: 1.000 ———————————————————————————— ANOVA Table ———————————————————————————————————————————— Source df Sum of Squares Mean Square F ———————————————————————————————————————————— Regression: 2 641953.80402913 320976.90201457 27473 Residual: 62702 732580.52344007 11.683527215082 Total: 62704 1374534.3274692 ———————————————————————————————————————————— Coefficient of Multiple Determination (R^2): 0.46703366456558
Nearest Neighbor Statistics ————————————————————————————————— Separation |Delta Z| ————————————————————————————————— Minimum: 1 0 25%-tile: 10.630145812735 0 Median: 11.313708498985 0.1
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75%-tile: 12.041594578792 0.1 Maximum: 37.483329627983 2.8 Midrange: 19.241664813991 1.4 Range: 36.483329627983 2.8 Interquartile Range: 1.4114487660576 0.1 Median Abs. Deviation: 0.72788607980753 0.1 Mean: 11.081622483966 0.10009090184192 Trim Mean (10%): 11.157973899595 0.082363781341324 Standard Deviation: 1.2740640359322 0.14717874072607 Variance: 1.6232391676559 0.021661581721711 Coef. of Variation: 0.11497089327629 1.4704507404531 Coef. of Skewness: -1.1923918374104 6.4565152536052 Root Mean Square: 11.154622182977 0.17798811857323 Mean Square: 124.42559604497 0.031679770353238 ————————————————————————————————— Complete Spatial Randomness Lambda: 0.00019359358700226 Clark and Evans: 0.30837476394917 Skellam: 9490.3610969425
Exclusion Filtering Exclusion Filter String: Not In Use
Duplicate Filtering Duplicate Points to Keep: First X Duplicate Tolerance: 0.0023 Y Duplicate Tolerance: 0.0019 Deleted Duplicates: 2 Retained Duplicates: 2 Artificial Data: 0 ———————————————————————————————————————————— X Y Z ID Status ———————————————————————————————————————————— 565728 357912 -1.7 62037 Retained 565728 357912 -2 62679 Deleted 565736 357882 -1.8 62040 Retained 565736 357882 -2 62676 Deleted ————————————————————————————————————————————
Breakline Filtering Breakline Filtering: Not In Use
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Gridding Rules Gridding Method: Kriging Kriging Type: Point Polynomial Drift Order: 0 Kriging std. deviation grid: no Semi-Variogram Model Component Type: Linear Anisotropy Angle: 0 Anisotropy Ratio: 1 Variogram Slope: 1 Search Parameters Search Ellipse Radius #1: 12900 Search Ellipse Radius #2: 12900 Search Ellipse Angle: 0 Number of Search Sectors: 4 Maximum Data Per Sector: 16 Maximum Empty Sectors: 3 Minimum Data: 8 Maximum Data: 64
Output Grid Grid File Name: C:\Users\nelwan\Desktop\backup pen\padl2\fixxx.grd Grid Size: 82 rows x 100 columns Total Nodes: 8200 Filled Nodes: 8200 Blanked Nodes: 0 Blank Value: 1.70141E+038 Grid Geometry X Minimum: 552092 X Maximum: 572028 X Spacing: 201.37373737374 Y Minimum: 356229 Y Maximum: 372476 Y Spacing: 200.58024691358 Grid Statistics Z Minimum: -25.813490141218 Z 25%-tile: -7.0612425821541 Z Median: -4.8795984891301 Z 75%-tile: -1.1085439118958 Z Maximum: 0.14892035461582 Z Midrange: -12.832284893301 Z Range: 25.962410495833 Z Interquartile Range: 5.9526986702583 Z Median Abs. Deviation: 3.0156350755944
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Z Mean: -5.0876223363258 Z Trim Mean (10%): -4.685584506359 Z Standard Deviation: 4.2240701109592 Z Variance: 17.842768302299 Z Coef. of Variation: -1 Z Coef. of Skewness: -1.2590425020269 Z Root Mean Square: 6.6126144103056 Z Mean Square: 43.726669339381
