This document contains a lecture on contour mapping given by Mohd Salman Ahmed, a lecturer in civil engineering at Ahmed's Institute of Excellence. The lecture discusses the characteristics of contours, how to read contour plans, and how to interpret information from contour maps. Key points covered include that contours have the same elevation, spacing depends on slope, closed contours indicate hills or depressions, and contours cannot cross except at overhanging cliffs. The document provides examples and a short quiz to assess understanding.

1. Department of Technical Education
Telangana
Name : Mohd Salman Ahmed
Designation : Lecturer
Branch : Civil Engg
Institution : Ahmed’s Institute Of Excellence
Year/semester : II year
Subject : Surveying III
Topic : Levelling
Duration : 100 minutes
Teaching aids : PPT, Animations, Diagrams
9C105.97 & 98 1

2. Objectives
• Upon completion of this topic, you would be able to
understand
• The characteristics of contours
• How to read contour plan
• How to get information from contour plan
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3. Contours
• Every point on contour has same elevation
• Contour plan will depict character of ground
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4. Characteristics of Contours (contd.)
2. The contour lines are closed curves. They may close
on the map itself or out side of the map depending
upon the topography
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5. Characteristics of Contours
1. The spacing between the contour lines depends upon
the slope of the topography
a) In steep slopes the spacing is small and for
gentle slopes the spacing is large
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Steep slope Gentle slope

6. Characteristics of Contours (Contd.)
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b) Uniformly placed contours indicate uniform slope

7. Characteristics of Contours (Contd.)
c) Straight and equally spaced contours indicate
plane surface
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8. Characteristics of Contours (Contd.)
d) If the contour lines are parallel, straight and
equally placed, they represent a plane surface
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Plane surface

9. Characteristics of Contours (Contd.)
3. A series of closed contour lines on the map or
plan indicate either hill or pond
a) In case of hill the values of elevation go on
increasing towards the centre
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10. Characteristics of Contours (Contd.)
b) A series of closed contours with higher values
outside indicate a depression
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11. Characteristics of Contours (Contd.)
4. Contour lines can not
end anywhere but close
on themselves
5. Contour lines can not
merge or cross one
another on map except
in the case of an
overhanging cliff
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Overhanging
cliff

12. Characteristics of Contours (Contd.)
6. A vertical cliff is indicated when several contours
coincide
 When the horizontal equivalent is zero they
coincide to form a one line and indicate a
vertical cliff
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13. Characteristics of Contours (Contd.)
7. The Contour lines form pair of loops in case of
“saddle”
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14. Characteristics of Contours
8. Irregular contours indicate rugged terrain
• A Ridge line is indicated when the values inside the
loop are higher
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15. Characteristics of Contours
10. A valley line is indicated when lower values are inside
the loop
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16. Summary
We have discussed
• The characteristics of contours
• How to read contour plans
• How to interpret contour maps
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17. Quiz
1. Closed contours with higher values inside represent
A. Hill
B. Depression
C. Flat surface
D. Steep slope
Ans: A
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18. 2. Closed contours with lower values inside represent
A. Hill
B. Depression
C. Flat surface
D. Steep slope
Ans: B
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Quiz (contd.)

19. 3. Contour lines merge or cross in a
a. Hill
b. Depression
c. Over hanging cliff
d. Vertical cliff
Ans: C
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Quiz (contd.)

20. 4. Contour lines coincide in case of
A. Hill
B. Depression
C. Overhanging cliff
D. Vertical cliff
Ans: D
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Quiz (contd.)

21. Frequently asked questions
1) Explain the characteristics of contours.
2) Draw neat sketches of contours for the following
a) Hill b) Vertical cliff
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22. AHMED’S INSTITUTE OF EXCELLENCEAHMED’S INSTITUTE OF EXCELLENCE
NEAR YAKUTPURA RAILWAY STATION, HYDERABAD, TELANGANA
TUITION CLASSES FORTUITION CLASSES FOR
 DIPLOMA, (CIVIL, MECHANICAL, ECE, EEE & CME)
 INTERMEDIATE,(MPC, CEC & HEC)
 DEGREE,(B.COM, BSC & BA)
 ENGINEERING (CIVIL, MECHANICAL, ECE, EEE & CSE)
CONTACT:CONTACT:
MOHD SALMAN AHMED 9700573988
DIRECTOR DCE.,BE.,ME