2.characteristics of countours

By salman ahmed

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

9C105.97 & 98 2

3. Contours
•Every point on contour has same elevation
•Contour plan will depict character of ground

9C105.97 & 98 3

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
9C105.97 & 98 4

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

9C105.97 & 98 5
Steep slope
Gentle slope

6. Characteristics of Contours (Contd.)
9C105.97 & 98 6
b) Uniformly placed contours indicate uniform slope

7. Characteristics of Contours (Contd.)
c) Straight and equally spaced contours indicate
plane surface
9C105.97 & 98 7

8. Characteristics of Contours (Contd.)
d) If the contour lines are parallel, straight and
equally placed, they represent a plane surface
9C105.97 & 98 8
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
9C105.97 & 98 9

10. Characteristics of Contours (Contd.)
b) A series of closed contours with higher values
outside indicate a depression
9C105.97 & 98 10

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
9C105.97 & 98 11
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
9C105.97 & 98 12

13. Characteristics of Contours (Contd.)
7. The Contour lines form pair of loops in case of
“saddle”
9C105.97 & 98 13

14. Characteristics of Contours
8.Irregular contours indicate rugged terrain
•A Ridge line is indicated when the values inside the
loop are higher
9C105.97 & 98 14

15. Characteristics of Contours
10.A valley line is indicated when lower values are inside
the loop
9C105.97 & 98 15

16. Summary
We have discussed
•The characteristics of contours
•How to read contour plans
•How to interpret contour maps
9C105.97 & 98 16

17. Quiz
1. Closed contours with higher values inside represent
A.Hill
B.Depression
C.Flat surface
D.Steep slope
Ans: A
9C105.97 & 98 17

18. 2. Closed contours with lower values inside represent
A.Hill
B.Depression
C.Flat surface
D.Steep slope
Ans: B

9C105.97 & 98 18
Quiz (contd.)

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

9C105.97 & 98 19
Quiz (contd.)

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

9C105.97 & 98 20
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
9C105.97 & 98 21

22. AHMED’S INSTITUTE OF EXCELLENCEAHMED’S INSTITUTE OF EXCELLENCE
NEAR YAKUTPURA RAILWAY STATION, HYDERABAD, TELANGANA
TUITION CLASSES FOR TUITION 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