Surveying and Mapping inSoil Resources and Watershed Management

Degree Program B.Sc in Soil Resources and
Watershed Management
Course title /code: Surveying and Mapping
(GISc4043)
Prepared by: Jemal Tefera(MSc)
2023
1

Surveying may be defined as the science of determining
the position, in three dimensions, of natural and man-
made features on or beneath the surface of the earth.
This is being carried out by finding the spatial location
(relative / absolute) of points on or near the surface of the
earth
Unit 1 Introduction
Definition & concept of surveying
2
The first stage in all the big projects is generally to
survey the area and to prepare plans.

The primary aims of field surveying are :
• To measure the Horizontal Distance between points.
• To measure the Vertical elevation between points.
• To find out the Relative direction of lines by measuring horizontal
angles with reference to any arbitrary direction and
• To find out Absolute direction by measuring horizontal angles with
reference to a fixed direction
3

Objectives of Surveying
• To collect field data;
• To prepare plan or map of the area surveyed;
• To analyses and to calculate the field parameters for setting out
operation of actual engineering works.
• To set out field parameters at the site for further engineering
works.
4

Use and importance of surveying
Surveying is a crucial activity in various fields and industries, and it plays a
significant role in many aspects of society.
Here are some of the key uses and importance of surveying:
• Land Development and Real Estate:
– Land Surveying: Land surveying is essential for determining property
boundaries, land divisions, and legal descriptions. It helps resolve property
disputes and ensures proper land use.
• Construction:
– Construction Layout: Surveyors provide accurate measurements and
layout points for construction projects. This ensures that buildings and
infrastructure are built according to design plans.
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• Infrastructure Development:
– Infrastructure Planning: Surveying is vital for planning roads,
bridges, railways, pipelines, and utility networks. It helps determine
the best routes and locations for these structures.
• Environmental Conservation:
– Environmental Assessment: Surveying is used to assess the impact
of construction or development on the environment, helping to
minimize negative consequences.
• Floodplain Mapping and Management:
– Floodplain Surveys: Surveying is crucial in mapping floodplains,
which aids in flood risk assessment, planning for flood control
measures, and insurance purposes.
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• Cartography and Mapping:
– Topographic Mapping: Surveying is used to create accurate topographic maps that
provide essential information for navigation, land use planning, and resource
management.
• Mining and Geology:
– Mineral Exploration: Surveying helps identify and locate mineral resources and
assess their economic viability.
• Agriculture:
– Farm Planning: Surveying assists in planning and designing efficient irrigation
systems, crop layouts, and land management.
• Infrastructure Maintenance and Monitoring:
• Asset Management: Surveying is used to monitor the condition of infrastructure over
time, allowing for timely maintenance and repair.
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• Navigation and Geolocation:
– GPS and Geospatial Data: Surveying technology contributes to the
Global Positioning System (GPS) and provides geospatial data for
applications like navigation, transportation, and location-based services.
• Urban Planning:
– Urban Development: Surveying helps urban planners assess land use,
transportation, and infrastructure needs for growing cities.
• Disaster Management:
– Emergency Response: Surveying data is used in disaster management to
assess damage, plan rescue operations, and support recovery efforts.
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• Legal and Boundary Disputes:
– Legal Evidence: Surveying provides legally defensible evidence in
boundary disputes, property rights cases, and land title issues.
• Scientific Research:
– Geological and Environmental Studies: Surveying supports
research in fields like geology, oceanography, and environmental
science by providing precise data.
• Wildlife Conservation:
– Habitat Mapping: Surveying helps create habitat maps to protect
and manage wildlife populations and ecosystems.
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• To prepare a contour map to know the topography of the area to
find out the best possible site for roads, railways, bridges,
reservoirs, canals, etc.
• To prepare a cadastral map which shows the
boundaries of fields, plots, houses and other
properties.
• To prepare a topographical map which shows hills, valleys,
rivers, forests, villages, towns etc
10

Con;t
• generally surveying is fundamental in ensuring accurate
measurements, facilitating development and planning,
supporting environmental conservation, and resolving
various land-related issues.
• It is a critical component in the advancement and
sustainability of society and various industries.
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Types of Surveying
• Surveying is primarily classified into two categories,
• (i) Plane Surveying, and (ii) Geodetic or Trigonometrically
Surveying.
• Plane Surveying is that the earth’s surface is plane, though in fact
it is a curved surface.
• The error in ignoring curvature of the earth’s surface is, however,
negligible for survey up to 250 sq. km area
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Figure 1.1 Plane Surveying
•Assume NS lines are parallel
•Assume EW lines are straight

• Geodetic Surveys
 Geodetic Surveying is type of surveying which consider the shape
of the earth as spherical or ellipsoid of revolution.
 In geodetic survey, line connecting two points on earth’s surface
thus becomes an arc.
 Geodetic survey requires knowledge of spherical geometry and
trigonometry, and is used when area involved is large and survey
demands high accuracy
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15
Allow for convergence Treat EW lines as great circles

Plain Surveying Vs Geodetic
Surveying
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Classification of Surveying
• Based on Nature of the Field
1. Land Surveying: Land surveys are conducted to determine the
boundaries and areas of tracts of land.
• Land surveying is classified in to three parts according to their field;
 Topographical Surveying: - This kind of surveying is to show the
topography of mountain, terrain, river, water bodies, and roads. It is
three-dimensional.
 Cadastral Surveying: - The main aim of these surveying is to fix
boundary lines, calculation of the area of land properties and preparation
of revenue map for the state
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 City Surveying: - This surveying is carried out for the
construction of roads, parks, water supply for any developing
township.
2. Hydrographic Surveys: mapping of large water bodies for the
purpose of navigation and construction of harbor works etc.
• Example: Hydrographic Survey of Lake Tana.
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3. Astronomical Surveys:-These Survey which are carried out for
determining the absolute location i.e. latitude of different place
on the earth surface and direction of line on the surface of the
earth by making observation to heavenly bodies i.e. stars & Sun.
4. Route surveying: These surveys are special types of surveys
conducted along a proposed route for highway, railway, sewer
line etc.
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❖ Classification of Surveying Based on Purpose
1.Engineering Surveying- for the execution of engineering works
such as roads, railways, dams.
2. Mine Survey- for the control of underground workings for
mineral extraction.
3. Geological Survey- for determining different strata in the earth
4. Military survey - for determining points of strategic importance
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5.Construction Surveying: is dedicated to ensuring accurate
positioning and measurement during construction projects.
• Surveyors set out reference points and provide guidance for
builders to construct structures according to design specifications.
6. Environmental Surveying: This type of surveying is conducted
to assess and monitor the environment.
• It includes studying and mapping ecological areas, tracking
changes in landscapes, and evaluating the impact of human
activities on the environment.
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7. Land Surveying: Land surveying involves determining the three-
dimensional positions of points and the distances and angles
between them on the Earth's surface.
• This is often used for establishing land boundaries, creating land
maps, and defining property lines.
8. Cadastral Surveying: Cadastral surveying pertains to delineating
land ownership boundaries, creating land records, and establishing
property boundaries for legal and taxation purposes.
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9. Archeological Survey: search for archaeological sites and
collect information about the location, distribution and
organization of past human cultures across a large area.
10. Hydrographic Surveying: Hydrographic surveying is concerned
with mapping water bodies like oceans, rivers, and lakes. This type
of surveying is essential for navigation, coastal development, and
marine resource management.
❖ Classification based on instruments
According to the instruments, used Surveying is classified in to:
1. Chain surveying: This is the simplest type of surveying in which
only linear measurements are taken with a chain or tape.
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2.Compass surveying: In compass surveying, the horizontal
angles are measured with the help of a magnetic compass, in
addition to the linear measurements with a chain or a tape.
3.Leveling: This is a type of survey in which a leveling
instrument is used for determination of relative elevations of
various points in the vertical plane.
4.Plane table surveys: In plane table surveys, a map is prepared
in the field while viewing the terrain after determining the
directions of various lines and taking the linear measurements
with telescopic alidade.
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5.Theodolite surveys: theodolite is a very precise instrument for
measuring horizontal and vertical angles.
The theodolite surveys can be broadly classified in two types:
(a) Traverse, (b) Triangulation.
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6. Total Station Surveying: Total stations integrate theodolite
functionalities with electronic distance measurement (EDM) to
measure angles and distances.
They are extensively used in engineering and construction surveys.
7. GPS Surveying (Global Positioning System): GPS technology
uses satellites to determine precise locations on Earth.
It's widely used in various surveying applications due to its accuracy
and efficiency in determining positions.
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8. Photogrammetric Surveying: Photogrammetry uses overlapping
photographs to create accurate maps or models.
• This technique can be executed with aerial or terrestrial
photographs and is used in various surveying applications.
`9. Laser Scanning Surveying: Laser scanning or LiDAR (Light
Detection and Ranging) technology is used to create precise 3D
representations of objects or landscapes.
• It's commonly used in topographic mapping, as-built surveys, and
archaeological studies.
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10. Remote Sensing: Remote sensing uses satellite or aerial
imagery to gather information about the Earth's surface.
• It's useful for various applications such as environmental
monitoring, land use planning, and agricultural assessment.
11. Drones (UAVs - Unmanned Aerial Vehicles): Drones equipped
with cameras or LiDAR sensors are used for aerial surveys.
• They provide high-resolution imagery and data, allowing for
efficient mapping and surveying.
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Unit two
Major techniques of ground surveying
Types of measurements in surveying.
There are two types of measurements in surveying Linear measurements
and Angular measurements
• Linear measurement is the basis of all surveying and even through
angles may be read precisely, the length of at least one line in tract must
be measured to supplement the angles in locating points.
• Linear measurement can be defined as a measure of length.
• The length of a table, the length of a piece of pipe and the
length of a football field are all examples of linear
measurement.

Linear measurements are further classified as follows:
A. Horizontal Distance
B.Vertical Distance
Horizontal distance measurement is measured in a horizontal
plane.
If distance is measured along a slope, it is reduced to its
horizontal equivalent.
•The equation for calculating horizontal distance,
•which is slope = rise/run x 100.
•Exersise1, if you have a slope percentage of 6 and a rise of 25
feet, the equation would look like 6 = (25/run) x 100.
•Calculate The horizontal distance between the two points

Solution: Multiply each side of the equation by the 'run'
variable. Continuing with the example of a slope percentage
of 6 and a rise of 25, the equation will look like this: run x 6 =
[(25/run) x 100)] x run.
The 'run' terms cancel on the right side of the equation and the
results can be simplified in the following equation: 6 x run =
2,500.
(run x 6) / 6 = 2,500 / 6
The horizontal distance between the two points is then 416.6
feet

Methods of measuring a horizontal distance:
• Tachometry (Stadia),
• Taping,
• pacing
• EDM and
• GPS

1.Pacing
• Pacing is one of the most valuable things learned in surveying, since
it has practical applications for everybody and requires no equipment.
• One pace is defined as two footsteps.
• To determine the average distance of one pace, the total distance
walked is divided by the number of paces that it takes to pace that
distance.
• Pacing is a method used to measure a distance and is often used with
a sighting or hand compass.
• Most commonly, pacing is split up into segments, such as chains,
which are set measures of distance.

• Exercise 2 :A person counted 88 paces by walking along 60.00 m
know length on level ground and 111 paces of unknown distance
AB.
• What is the pace length and the length of AB?
Solution
pace length = 60.00m/88 = 0.6818 m/pace length of
AB = 0.6818*111 = 75.6798 ≈ 75.680
2.TAPING
• Measurement of horizontal distances by taping consists of
applying the known length of a graduated tape directly to a line
for a number of times.

Taping Equipment and Accessories

Fixing position of station points in surveying
• fixing the position of station points involves determining their
precise locations relative to a known coordinate system or
established benchmarks.
• Several methods and techniques are used to achieve this:
• Using Control Points: Control points are precisely measured and
marked points that serve as a reference for determining the
positions of other points in a survey.
• These control points might be established by geodetic survey
methods or through known benchmarks.

• Global Navigation Satellite Systems (GNSS): Using satellite-based
systems like GPS (Global Positioning System), GLONASS, or
Galileo, surveyors can determine accurate positions of station points
by receiving signals from satellites. GNSS allows for highly accurate
positioning in a global coordinate system.
• Trilateration and Triangulation: Trilateration involves measuring
distances between the station point and at least three known points
with known coordinates.
• Triangulation involves measuring angles between the station point and
two known points.
• Both methods help calculate the precise position of the station point.

• Leveling: Leveling is used to determine the elevation or height of
station points relative to a chosen vertical datum. This is crucial in
construction and topographic surveys to establish accurate
heights.
• Total Stations and Theodolites: These instruments measure
angles and distances, providing precise horizontal and vertical
measurements to establish station points' positions in relation to
each other or known control points.
• Astronomical Observations: Historically used and still
sometimes applied in specialized surveys, astronomical
observations involve using celestial bodies to determine positions

• However, this method is less commonly used due to the
widespread availability of more accurate and efficient
technologies.
• Aerial and Satellite Imagery: High-resolution imagery from
satellites or aerial platforms is used to identify and mark the
positions of station points in some surveys, especially in remote
or large-area surveys.

Ranging out
• The process of establishing intermediate point on a straight line between
two end points is known as ranging
• The intermediate points are located by means of ranging rodes, offset
rods and ranging poles.
• The establishment of fixation of such intermediate points is
accomplished utilizing ranging rods or ranging poles.
• Generally, when the length of the survey line is longer than the length of
the chain, the total length cannot be determined by chaining alone.
• In such a case, the intermediate points along the survey line are
determined by ranging.

Types of Ranging in Surveying
1. Direct Ranging
• Direct ranging is the ranging conducted when the intermediate
points are intervisible.
• Direct ranging can be performed by eye or with the help of an eye
instrument.
• let A and B are the two intervisible points at the ends of the survey
line. The surveyor stands with a ranging rod at the point A by
keeping the ranging rod at the point B.
• The ranging rod is held at about half meter length.

b. Indirect Ranging
Indirect Ranging is the method of ranging that is used when the two
endpoints of the survey line are either not inter-visible or the two
points are at a very long distance.
This may be due to some kind of intervention between the two
points. In this case, the following procedure is followed.

Fig.3. Indirect Ranging
As shown in figure-3, two intermediate points are located M1 and
N1 very near to chain line by judgment such that from M1, both N1
and B are visible & from N1 both M1 and A are visible.

SETTING OUT RIGHT ANGLES
• To set out right angles in the field, a measuring tape, two ranging
poles, pegs and three persons are required
• The first person holds together, between thumb and finger, the
zero mark and the 12 metre mark of the tape. The second person
holds between thumb and finger the 3 metre mark of the tape and
the third person holds the 8 metre mark.
• When all sides of the tape are stretched, a triangle with lengths of
3 m, 4 m and 5 m is formed (see Fig. 20), and the angle near
person 1 is a right angle

Obstacles in horizontal distance measurement
• Taping is a common method used for horizontal distance
measurement and is quite a simple task when it consists
measuring directly between two points without any obstruction
in between.
• Nevertheless, not all situations are perfect and it is very
common to encounter obstacle during the process of
measuring distance.
• measuring horizontal distances accurately is crucial for
mapping, construction, and various engineering projects.

Several factors or obstacles can pose challenges to obtaining precise horizontal
measurements:
• Terrain and Topography: Uneven or rough terrain, such as hills, valleys, and
irregular landscapes, can hinder direct line-of-sight measurements for horizontal
distances.
• Surveyors might need to navigate challenging landscapes, which can affect the
accuracy of measurements.
• Vegetation and Foliage: Dense vegetation, forests, or foliage obstruct the
direct line of sight between the surveying instruments, making it difficult to
measure horizontal distances.
• This requires clearing or finding alternative measurement methods, which
might be time-consuming and affect accuracy.

• Man-Made Structures: Buildings, structures, or other man-
made obstacles can obstruct the line of sight necessary for
accurate horizontal distance measurements.
• This often necessitates finding alternative measurement points or
angles to overcome these obstructions.
• Urban Settings: In urban environments with numerous
buildings and structures, surveyors face challenges due to the
presence of obstacles that block the direct measurement path.
• This may require the use of reflective targets or the elevation of
surveying instruments to obtain accurate measurements.
• Weather Conditions: Adverse weather conditions like fog, rain,
or extreme heat can interfere with the accuracy of electronic
distance measurement devices, affecting the precision of
horizontal measurements.

Surveyors employ various techniques to overcome these obstacles in
horizontal distance measurement, such as:
• Using Reflective Targets: Reflective targets can be placed to bounce signals
back to the surveying instruments, enabling measurements despite obstacles.
• Utilizing Remote Sensing Technologies: Remote sensing methods like LiDAR
(Light Detection and Ranging) and GPS technology can assist in gathering data
from challenging terrains or obstructed areas.
• Employing Alternative Measurement Methods: In situations where direct
measurement is not feasible, indirect methods like triangulation or the stadia
method may be employed to estimate horizontal distances.
•

• The three main obstacles in chaining of a line are of the
following types:
1. Chaining Free, Vision Obstructed
2. Chaining Obstructed, Vision Free
3. Chaining and Vision Both Obstructed.
1. Chaining Free, Vision Obstructed:
In this type of obstacles, the ends of the lines are not intervisible e.g.
rising ground, hill or jungle intervening.

• Chaining-Free Conditions: Traditionally, surveyors measured
distances using chains or tapes.
• Chaining-free conditions refer to situations where the use of
physical measuring devices like chains or tapes is impractical or
impossible due to obstacles such as rough terrain, water bodies,
dense vegetation, or urban structures.
• In these cases, direct physical measurements with traditional tools
are hindered or not feasible.
• Vision-Obstructed Conditions: Vision-obstructed conditions
occur when obstacles, such as buildings, dense foliage, or natural
features, prevent a direct line of sight between the surveying
instruments or points.
• These obstacles hinder the ability to visually observe or measure
distances accurately.

• Cases1 Both ends may not be visible from any intermediate point
such as in the case of a jungle. The obstacle of this kind may be
crossed over by “Random line method”.

In fig. 3.20, let AB be the line whose length is required.
From A, run a line AB’ called a random line, in the approximate
convenient direction of AB and continue it until point B is visible
from B’ Chain the line to B’ where BB’ is perpendicular to AB’
and measure BB’.
Similarly a number of points can be located on the true line.
The line is then cleared and chained.

2. Chaining Obstructed, Vision Free:
• Chaining Obstructed: This refers to situations where physical
obstructions or challenging terrain prevent the use of traditional
measuring tools like chains or tapes.
• The obstacles might include dense vegetation, water bodies,
rugged terrain, or urban structures, making it impractical or
impossible to directly measure distances through traditional
means.
• The problem consists in finding the distance between convenient
points on the chain line on either side of obstacle.

• Vision Free: In contrast, having a vision-free condition means
that a direct line of sight between surveying points is
unobstructed.
• Case (i) The distance between two points A and B on either side
of the pond may be determined by any of the following methods
convenient at site:
• To overcome the challenges of chaining obstruction while having
a clear line of sight, surveyors used :
(EDM) , Total Stations, Remote Sensing Technologies:

a) Set out equal perpendiculars AC and BD [Fig. 3.21 (a)].
Measure CD which is equal to AB.

(b) Erect perpendicular AC [Fig .3.21(b)] of such a length that CB
clears the obstacle and measure AC and CB.

3.Chaining and Vision Both Obstructed:
The scenario of chaining and vision being obstructed simultaneously can
occur due to various factors:
• Physical Obstructions: This could involve dense vegetation, buildings,
rugged terrain, or other obstacles that block the use of physical
measuring tools like chains or tapes. Simultaneously, these obstructions
hinder the ability to visually observe or sight points directly.
• Environmental Conditions: Harsh weather conditions, extreme terrain
features, or geographical barriers might impede both direct physical
measurements and obstruct the line of sight between the surveying
points.

To address such a situation ,surveyors must rely on alternative techniques:
• Remote Sensing Technologies: LiDAR, aerial surveying with drones, or radar
systems can be used to collect data in areas where both physical measurements and
direct visual observation are impossible due to obstructions.
• Geophysical Methods: Ground-penetrating radar or seismic surveying techniques
might provide indirect measurements and information without requiring a clear line of
sight.
• mapping and Satellite Data: Utilizing existing maps, satellite imagery, and GIS
(Geographic Information System) data can help in estimating distances and creating
models even without direct measurement or sight.
• Non-contact Measurement Devices: Laser-based or ultrasonic distance measuring
tools that do not require a direct line of sight can aid in determining distances in
scenarios where traditional chaining and visual observations are obstructed.

(a) Select two points A and B on the chain line [Fig. 3.23 (a)].
• At A and B, erect equal perpendiculars AC and BD. Join CD and
produce it past the obstacle.
• Select two points E and F on it. At E and F, set out
perpendiculars EG and FH, each equal in length to AC. The
points G and H then lie on the chain line and BG = DE.

The direction and length of perpendiculars must be set out with
great accuracy.
The check can be made by measuring diagonals of the rectangles.
For the same rectangle, diagonals should be equal.
 Here AD should be equal to BC, and EH equal to FG.

OFFSET is a distance measured at a right angle from a baseline or
survey line to locate or mark a point that isn't directly on that line.
Offsets are taken to locate objects with reference to the chain line.
• They may be of two kinds.
1. Perpendicular offset and
2. Oblique offset.
• Perpendicular offset: When the lateral measurements are taken
perpendicular to the chain line, they are known as perpendicular
offsets
OFFSET IN CHAIN SURVEY

 A perpendicular offset in surveying refers to a method of determining the
position of a point or object that is situated at a right angle to a baseline or
survey line.
 It involves measuring the distance from the baseline to the target point at a
perfect 90-degree angle.
Key points about perpendicular offsets include
Accuracy and Precision: Surveyors use tools like total stations, theodolites, or
tape measures to obtain accurate perpendicular distances.
 This ensures the precise location of points or features in relation to the
baseline.
Mapping and Surveying: They are crucial in creating accurate maps,
determining property boundaries, establishing construction layouts, and
recording positions of physical features or structures relative to a known line.

Oblique offset: involves a measured distance that is taken at an angle
other than 90 degrees from the survey line or baseline.
It requires both the measurement of distance along the line and the
measurement of the angle at which the point is situated from the line
Fig. Perpendicular offset

• An oblique offset is used when the point of interest is not directly in
line with the survey baseline and requires a diagonal or slanted
measurement to locate the point accurately.
Key points about oblique offsets include:
• Angle Measurement: When a point needs to be marked that is not
directly in line with the survey baseline, an oblique offset is used.
• It involves measuring both the distance from the baseline and the
angle at which the measurement is taken from the baseline to the
point of interest.

• Calculation and Accuracy: Calculations for oblique offsets
involve trigonometry, as the measured distance along the
line and the angle relative to the line are necessary to
accurately determine the coordinates of the target point.
• Precision and Technique: Surveyors use specialized
instruments like theodolites or total stations to obtain
accurate angles and distances required for oblique offsets.

Suppose AB is a chain line and p is the corner of a building.
Two points ‘a’ and ‘b’ are taken on the chain line.
The chain ages of ‘a’ and ‘b’ are noted.
 The distance ‘ap’ and ‘bp’ are measured and noted in the field
book.
Then ‘ap’ and ‘bp’ are the oblique offsets.

Offsets are useful for several purposes:
• They help locate objects or points that are not directly accessible
from the survey line due to obstacles or other conditions.
• Surveyors take measurements from the survey line to the point
where the offset intersects, recording both the perpendicular
distance (offset distance) and the angle to accurately mark the
point's position.
• These measurements assist in creating accurate maps, property
boundaries, construction layouts, and other surveying tasks by
accurately plotting the positions of various features in relation to a
known line or baseline.

• Trigonometry is derived from the Greek
words trigonon (triangle) and metron (measure).
• It is a branch of Mathematics that deals with the relationships
between the lengths and angles of the sides of triangles.
• A trigonometric equation is an equation involving one or more
trigonometric ratios of unknown angles.
• It is expressed as ratios of sine(sin), cosine(cos), tangent(tan),
cotangent(cot), secant(sec), and cosecant(cosec) angles.

Trigonometric Equations Formulas
• Consider a right-angled triangle, as shown in Figure 1. From the
figure, ∠A made is an acute angle.

• From the figure, the following trigonometric ratios can be
deducted

• Each of these trigonometric ratios can be evaluated at different
angles.
• Some standard angles are given in Table 1 for each of the ratios.

• Remark: From Table 1 above, you can observe that as ∠ A
increases from 0° to 90°, sin A increases from 0 to 1, and cos A
decreases from 1 to 0.

• Ground surveying is the process of gathering information about the Earth's
surface to create maps, plan construction projects, or conduct other activities
that require precise spatial data.
Principles:
Accuracy and Precision:
– Accuracy refers to how close a measured value is to the true value.
– Precision relates to the consistency of repeated measurements.
– Both accuracy and precision are crucial for reliable surveying results.
Control Points:
– Establishing control points with known coordinates is essential for
referencing and georeferencing survey data.
Unit 3
Principles and techniques of ground surveying

Error Analysis:
– Identifying and minimizing errors in measurements through
careful analysis is fundamental for accurate surveying.
Datum and Coordinate Systems:
– Using a common datum and coordinate system ensures
consistency in measurements and facilitates accurate mapping.
Measurement Units:
– Consistent use of measurement units (e.g., meters, feet) is critical
for accurate calculations and map representation.
Field Notes and Documentation:
Accurate and detailed field notes provide a record of surveying activities,
equipment used, and any issues encountered.

Techniques:
Triangulation:
– Determining the location of a point by measuring angles to it from known
points, forming a triangle.
Trilateration:
– Determining the position of a point by measuring the distances to it from
three known points.
Leveling:
– Measuring the height differences between points to establish elevations
and contours.
Total Station Surveying:
– An electronic/optical instrument for measuring angles and distances, often
used for detailed mapping and construction projects.

Global Navigation Satellite Systems (GNSS):
Utilizing satellite signals for precise positioning and surveying.
Examples include GPS (Global Positioning System).
Theodolite Surveying:
Using a theodolite to measure horizontal and vertical angles,
often employed in topographic surveys.
Magnetic Surveying:
Measuring the magnetic field of the Earth to determine the
location and extent of magnetic anomalies.

• Magnetic anomalies refer to variations in the Earth's magnetic
field strength at a particular location.
• The Earth's magnetic field is not completely uniform, and there are
areas where the magnetic field strength is either stronger or weaker
than the average expected magnetic field strength for that
geographic location.
• These variations are what we term magnetic anomalies.

There are two main types of magnetic anomalies:
• Positive Magnetic Anomaly:
– A positive magnetic anomaly occurs when the magnetic
field strength at a particular location is stronger than the
expected average for that region.
– This indicates the presence of materials with higher
magnetic susceptibility, such as iron-rich rocks or minerals.

Negative Magnetic Anomaly:
• A negative magnetic anomaly occurs when the magnetic field
strength is weaker than the expected average.
• This can be associated with materials that have lower magnetic
susceptibility, or it might indicate the presence of non-magnetic
materials.
• The detection and mapping of magnetic anomalies are crucial in
various fields, including geophysics, archaeology, and mineral
exploration.
• Instruments like magnetometers are used to measure and record
these variations in magnetic field strength

• The magnetic survey technique is based on mapping localized
variations in the Earth’s magnetic field caused sub-surface
magnetic materials, which range from naturally occurring magnetic
minerals to man-made ferrous objects/ iron-containing/.
Test For:
Location of Buried Ferrous Objects
Location of Geologic Variations

Remote Sensing:
Collecting data from a distance, often using satellites or aerial platforms,
for mapping and monitoring purposes.
Ground Penetrating Radar (GPR):
Using radar pulses to image the subsurface, useful for detecting buried
objects or studying geological features.
 GIS (Geographic Information System):
Integrating, analyzing, and visualizing spatial data for better decision-
making.
 Photogrammetry:
Extracting spatial information from photographs to create maps or 3D
models.

Units of measurement in surveying
Standard unit of measurement :-A unit of measurement refers to a
specific magnitude of a quantity, described and approved by
convention or by law, that is used as a standard for measurement of
the same kind of quantity.
Type - metric unit
Length - inches, feet, yards, miles - millimeters, centimeters, meters,
kilometers
Weight - ounces, pounds - grams, kilograms
Time - seconds, minutes, hours
Volume - ounces, gallons - milliliters, liters

• There are four systems used for plane angle measurements,
namely the sexagestimal, the centesimal, Hours System and
radiant (arc units).
• Sexagestimal units are used in many parts of the world and
measure angles in degrees, minute and seconds of arc.
• A circle is divided into 360 equal degrees, so that a right angle is
90.
• Degrees may be further divided into minutes and seconds.

• But parts of a degree are now frequently referred to
decimally.
• For instance seven and a half degrees is now usually
written 7.5°.
• 1 full circle = 360 (degrees)
• 1’ = 60” (seconds)
• 60’ =(3600 second)

There are three popular systems of angular
measurement.

Centesimal: the circle is divided into 400 parts.
• 1 full circle = 400 gon
• 1 gon = 1/400 full circle = 2p/400 rad = p/200 rad
• 1 gon = 100 cgon (centigon)
• 1 cgon = 10 mgon (milligon)
• 1 mgon = 10 cc (centi centigon)

a) Conversion of length
• 1 inch = 2.54 cm
• 1 foot = 0.3048m
• 1 mile = 1.6093 km
b) Conversion of area
• 1 sq in = 6.4516 sq cm
• 1sq ft = 0.0929 sq m
• 1 sq mile = 2.59 sq km

C) conversion of volume
• Volume is measured in cubic units
• 1 cu in = 16.387 cu cm
• 1 cu ft = 0.0283 c um
• D) conversion of angles
The two most common units of measurement for angles are
degrees and radians
• 1 gon = 9/10 deg
• 1 deg = 10/9 gon

exersise1
• convert from gon to degree: 48.0488 gon
• Convert from degree to gon: 43.2439°
Radian units are another unit of angle measurement used in most
software’s, consider the unit circle (a circle of radius 1) whose
center is the vertex of the angle in question.
Then the angle cuts off an arc of the circle, and the length of that
arc is the radian measure of the angle.

The circumference of the entire circle is 2 ( is
about 3.14159), so it follows that 360° equals 2
radians. Hence, 1° equals /180 radians and 1
radian equal 180/ degrees.
1 radian = 57.2957 degrees, 1 degree = 60’
60’ =3600 ‘’
3600 ‘’= 0.0174532 radians.

Error and mistakes
• Error is defined as the difference between two or more measured
values of the same quantity.
• Are the difference between a measured value and its true value.
• However, measurements are never exact and there will always be
a degree of variance regardless of the survey instrument or
method used.
• surveyors must possess skill in instrument operation and
knowledge of
surveying methods to minimize the amount of error in each
measurement.

Types of Errors
• There are two types of errors, systematic and random. It
is important for the surveyor to understand the difference
between the two errors in order to minimize them.
A. Systematic errors
systematic errors are caused by the surveying equipment,
observation methods, and certain environmental factors.
Under the same measurement conditions, these errors will
have the same magnitude and direction (positive or negative).

Several types of systematic errors
Instrumental Errors:
– Result from imperfections or mis calibrations in surveying
instruments, such as theodolites, total stations, or leveling
instruments.
Environmental Conditions:
– Changes in temperature, humidity, or atmospheric pressure can
affect the accuracy of measurements, particularly in optical
instruments.
Personal Errors:
– Mistakes made by the surveyor, such as misreading instrument
scales, mis recording data, or incorrectly setting up equipment.

• Natural Features:
– The presence of natural obstacles or features, such as
vegetation or terrain, can obstruct measurements or
introduce errors.
• Incorrect Reference Points:
– Using inaccurate or incorrectly established control points
as references can propagate errors throughout the survey.

 properly leveling the survey instrument and targets.
 Balancing foresight and back sight observations.
 Entering the appropriate environmental correction
factors in the data collector.
 Entering the correct instrument heights, targets
heights, and prism offset in the data collector.
 Periodically calibrating the surveying equipment
The effect of these errors can be minimized by:

B. Random errors
• Random (or accidental) errors are not directly related to the
conditions or circumstances of the observation.
• For a single measurement or a series of measurements, it is
the error remaining after all possible systematic errors and
blunders have been eliminated.
• Random errors are unpredictable and are often caused by
factors
beyond the control of the surveyor.
• Their occurrence, magnitude, and direction (positive or
negative) cannot be predicted.

Type of random Error
• Instrument Precision:
– Even with well-calibrated instruments, there is always a degree
of uncertainty in measurements due to limitations in the precision
of the equipment.
• Observational Errors: Variability in the surveyor's ability to
consistently make observations, especially over extended periods,
can introduce random errors.
• Atmospheric Conditions: Fluctuations in atmospheric conditions,
such as air turbulence or refraction, can lead to unpredictable errors
in measurements.

• Instrument Drift:
– Gradual changes in the performance of instruments over time
can result in drift, leading to inaccuracies in measurements.
Mistakes:
• A 'mistake' is usually accidental, you know it is wrong.
Otherwise, an 'error' is usually made due to the lack of knowledge
and is more formal than 'mistake.
• Data Entry Errors: Incorrectly transcribing or entering field data
into computers or notebooks can lead to mistakes that affect the
accuracy of the final survey.

• Miscommunication:
– Lack of clear communication among survey team members
can result in errors in instrument setup, measurements, or
data recording.
• Misinterpretation of Plans:
– Errors may occur if surveyors misinterpret project
specifications, plans, or instructions.
• Procedural Errors:
– Mistakes in following established survey procedures or
protocols can compromise the accuracy of the survey.

Tools and instruments of ground surveying
• Land Surveyors use a wide variety of tools and equipment in
their day to day work; it will vary depending on the type of survey
being done, here’s a few examples
1. Drones are unpiloted aircraft or spacecraft.
• Surveyors use them because they provide a fast, safe and cost-
efficient way to survey at height.
• drone application area in forestry, where drones can even save
human lives, is handling forest fires.

• The drones can for example help the firemen to keep track of fire
fronts and identify the location and intensity of hotspots, helping the
decision makers direct the firefighting activities.
• Using drone technology, we can map and survey a variety
of environmental factors — land erosion, wildfire risk,
invasive species growth, endangered species populations,
and more.
• Organizations can then use the data to make better, more
informed decisions that protect humans and nature alike

2. Theodolite: A surveying instrument with a rotating telescope for
measuring horizontal and vertical angles to make precise measurements
of areas and triangulate the position of objects in a specific area.
3.Measuring tape: A length of tape or thin flexible metal, marked at
intervals for measuring size or distance. Surveyors commonly use tape
measures (known as measuring wheels) in lengths of over 100 meters
4.Total station: A total station is an electronic optical instrument used for
surveying and construction.
It integrates the functions of a theodolite and distance meter, allowing
surveyors to measure angles and distances simultaneously.
This tool is used to record features in topographic surveying or to set out
features (roads, houses, or boundaries)

5. 3D scanners: A surveying instrument that can accurately
measure and collect data from objects, surfaces, buildings, and
landscapes.
• This tool collects information in the form of point cloud data,
which consists of millions of 3D coordinates.
• These coordinates can be used to create 3D computer-aided
design (CAD) models, which can then help analyze
topographic features and structures.
• The high accuracy of 3D scanners helps reduce project costs

6.GPS/GNSS: The use of Global Positioning System
signals and/or Global Navigation Satellite System
signals via a receiver and antenna to determine the
form, boundary, position, objects, or points in space
relative to other forms, boundaries, or points.
• This technology has dramatically increased the speed
and productivity of surveyors using on-demand
centimeter-level accuracy provided by Real-Time
Kinematic (RTK) positioning

7.Level and rod: A graduated wooden or aluminum rod, used with a
leveling instrument to determine the difference in height between
points or heights of points above a vertical datum.
• This tool is used to establish and verify elevations.
8. Field Book:
• Field books are used by surveyors to record measurements, sketches,
and other data collected during the survey.
• They are essential for maintaining an organized record of the survey
work.

Total station Theodolite
Level and rod:

Unit 4 Chain surveying
the chain survey is the simplest method of surveying. In the chain
survey, only measurements are taken in the field, and the rest work,
such as plotting calculation, etc. are done in the office.
 Here only linear measurements are made i.e. no angular
measurements are made.
This is most suitably adapted to small plane areas with very few
details. If carefully done, it gives quite accurate results.

The necessary requirements for fieldwork are
• Chain
• Tape
• Ranging-Rod
• Arrows
• Cross staff

Tape used for Chain Surveying
Metallic Tape
• Cloth tapes reinforced with brass, copper and bronze wires to prevent it
from stretching.
• They are available in lengths 10, 15, 20 and 30m.
• Tape is provided in leather case fitted with winding device.
Steel Tapes
• Outer end of the tape carries better links for its easy handling and the
length of tape is inclusive of this ring.
• Steel tapes are light, delicate and are used for measurements of distance
with high degree of accuracy.

Ranging Rods
• 2m to 3m length and 2.5m diameter painted alternately with black or
white.
• An iron shoe provided at its bottom enable it to the fixed at a
required point in the ground.
• A coloured flag is provided at its tops so that it can be easily seen
from a long distance.

Arrows
• Arrows or marking pins or chaining pins are used to mark the end
of each chain during the process of chaining.
• 400mm in length are pointed at one end for intersecting into the
ground and bend into a ring at the other end for facility of carrying.
• A piece of white or red tape tied to the ring so that they can be made
easily visible at a distance.

Procedure in Chain Survey
1.Reconnaissance: The preliminary inspection of the area to be
surveyed is called reconnaissance.
The surveyor inspects the area to be surveyed, surveyor prepares
index sketch or key plan.
2.Marking Station: The surveyor fixes up the required no stations at
places from where maximum possible stations are possible.

Some of the methods used for marking are:
Fixing ranging poles
Driving pegs
Marking across if the ground is hard
Digging and fixing a stone.
Then he/she selects the way for passing the mainline, which should be
horizontal and clean as possible and should pass approximately
through the center of work.

3. Selection of Survey Lines:
• Determine the survey lines based on the objectives of the survey.
• These lines should form a closed figure to facilitate the closure of
the survey.
4.Setting Up Instruments:
• Set up necessary instruments at each survey station.
• In chain surveying, theodolites or compasses are commonly used
for measuring angles, and chains or tapes are used for measuring
distances.

5. Orientation:
• Orient the instrument at the first station to establish a reference
direction.
• This is essential for maintaining consistency in angle
measurements throughout the survey.
6. Measurements of Angles:
• Use the theodolite or compass to measure the interior and
exterior angles at each station.
• These measurements help in plotting the survey lines accurately.

7. Measurement of Distances:
• Use a chain or a tape to measure distances along the survey lines.
• The chain is laid along the ground, and distances are measured
by aligning the chain with the line.
8. Booking of Field Observations:
• Record all the field observations, including angle measurements,
distance measurements, and any other relevant data, in a field
book.
• Proper documentation is crucial for later analysis and mapping.

10. pacing or Stepping:
• In cases where precision measurements are not required, pacing
or stepping can be used to estimate distances.
• Pacing involves walking a known distance, counting the number
of steps, and using this information to estimate distances.
11. Closing the Survey:
• After completing the survey lines, close the survey by returning
to the starting point and checking for closure errors.
• Any discrepancies in the measurements may be adjusted to
ensure the survey forms a closed figure.

Plotting:
• Use the recorded field observations to plot the survey lines on a
map or drawing.
• This is typically done in the office or on a drawing board.
Calculation of Areas:
• If the survey is intended for land area measurement, calculate
the areas enclosed by the survey lines using appropriate
mathematical formulas.

Calculate Areas of Subdivisions:
•Calculate the areas of each smaller shape using the
appropriate formulas.
•For example:
For rectangles or squares:
Area=Length × Width
For triangles:
Area=1/2×Base × Height

Example: What is the area of a triangle with base b = 3 cm and
height h = 4 cm?
• Using the formula,
• Area of a Triangle, A = 1/2 × b × h

Area of an Equilateral Triangle
• An equilateral triangle is a triangle where all the sides are equal.
The perpendicular drawn from the vertex of the triangle to the base
divides the base into two equal parts.
• To calculate the area of the equilateral triangle, we have to know the
measurement of its sides.
Area of an
Equilateral Triangle
A = (√3)/4 × side2

Area of a Circle
• The area of a circle is the space occupied by the circle in a two-
dimensional plane
• The formula for the area of a circle is A = πr2, where r is the
radius of the circle.
Example 1: If the length of the radius of a circle is 4 units.
Calculate its area.
Solution:
• Radius(r) = 4 units(given)
• Using the formula for the circle's area,
• Area of a Circle = πr2
• Put the values,
• A = π(4)2

• The below table shows the list of formulae if we know the
radius, the diameter, or the circumference of a circle.

Principal Of Chain Surveying
• (i) First of all, the site should be inspected with a view to find a suitable
location for stations.
• (ii) The survey lines should be as few as practicable and such that the
framework may be plotted.
• (iii) If possible, a base line should be run roughly through the middle of the
area on which the framework of triangles covering the major portion of the
area may be built up.
• (iv) All the triangles should be well conditioned, i.e., no angle should be less
than 30° or greater than 120° in a triangle.

• (v) Each portion of the survey should be provided with check lines.
• (vi) The offsets should be short; particularly for locating features which are
important.
• A number of subsidiary lines or tie lines should be run to locate the details and
to avoid long offsets.
• (vii) As few lines as possible should be run without offsets.
• (viii) The obstacles to ranging and chaining should be avoided as far as
possible.
• (ix) The lines should lie as far as possible on the ground level.

• (x) In lines lying along a road, the possibility of interruption during chain
surveying, a line at one side of the road should be drawn.
• (xi) The main Stations should be inter-visible and the main principle of
surveying, i.e., working from the whole to the part, should be strictly
observed.
• (xii) The lines should be measured in order to avoiding unnecessary
walking between stations.

Con;t
Generally the principal of chain surveying is to divide the area into
a number of triangles of suitable sides.
As a triangles is the only simple plane of
geometrical figure which can be plotted from the
lengths of the three sides even if the angels are
not known.

1. A network of triangles (triangulation) is preferred to in chain
surveying.
2. If the area to be surveyed is triangular in shape
and if the lengths and sequence of its three
sides are recorded the plane of area can be easily
drawn

TERMS RELATED WITH CHAIN SURVEYING

SURVEY STATIONS
• Survey stations are the points at the beginning
and at the end of the chain line.
• They may also occur at any convenient position on the chain line.
Such stations may be :
• Main stations
• Subsidiary stations
• Tie stations

(1) Main stations :Stations taken along the boundary of an area as
controlling points known as ‘main stations’.
• The lines joining the main stations are called
‘main survey lines’.
• The main survey lines should be cover the whole area to be
surveyed.
• The main stations are denoted by with letters A,B,C,D, etc.

(2) Subsidiary stations: Stations which are on the main survey lines
or any other survey lines are known as ‘Subsidiary stations’.
• These stations are taken to run subsidiary
lines for dividing the area into triangles , for checking the accuracy
of triangles and for locating interior details.
• these stations are denoted by ‘ ‘with letters S1, S2, S3,etc.

3)Tie stations: These are also subsidiary stations taken on the main
survey lines.
• Lines joining the tie stations are known as ‘tie lines’.
• Tie lines are taken to locate interior details.
• The stations are denoted by ‘ ’ with letters T1, T2, T3, etc.

(4) BASE LINE: The line on which the framework of the survey is built is
known as the ‘base line’ .
• It is the most important line of the survey .
• Generally , the longest of the main survey line is considered as the base line.
• This line should be measured very carefully and accurately. In fig.BD is the
baseline

(5) CHECK LINE:
• The line joining the apex point of a triangle to some
fixed points on its base is known as the ‘check line’.
• It is taken to check the accuracy of the triangle .
• Sometimes this line is helps to locate interior details
. In fig. CS1, AS2 are the check lines.
6.Offsets:
• The details like corners of buildings, roads, fences, etc., included
within the sketch of the survey, are measured by lateral
measurements with respect to main survey lines.

Office work in chain surveying
• What are the works of a surveyor in office?
• Drafting, computing, and designing are the office works that
have to be performed by the surveyor.
• The drafting performed consists of the preparation of plans and the
sections.
• These must be plotted to the measurement and to scale and
prepare the topographic maps.

plotting and mapping
• After collecting /determining the positions of points on the surface
of the earth and measuring the distances, directions, angles, and
elevations between them.
• This data helps accurately create maps and determine plot
boundaries by using different soft wears like that of GIS,RS and
AutoCAD

a mapped area of land with specified characteristics.
• Land mapping units are defined and mapped by natural resource
surveys, e.g. soil survey, forest inventory.
• Their degree of homogeneity or of internal variation varies with
the scale and intensity of the study.

In this chapter there is filed survey and lab work
1.colection of single plot of land l.e rectangle or triangle by using
GPS
2.Conversison of DMS collected data in to km and meter
3.Intering the collected data in to the computer by using excel
4.Creation of plotting and mapping

Surveying and Mapping inSoil Resources and Watershed Management

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