Toposheets are very essential tools for all civil engineering projects. This report highlights these details in a condensed form.

1. USE OF TOPOSHEETS IN CIVIL ENGINEERING PROJECTS
ARJUN. K & DR.A.BALASUBRAMANIAN
DOS IN EARTH SCIENCE
UNIVERSITY OF MYSORE

2. Contents
• Introduction
• Contour
• Contour interval
• Types of slope
• Topographic survey
• Types of Landforms
• Use of Toposheets in Civil Engineering Projects
• Conclusion
• Reference

3. Introduction
• Topographic maps are detailed,accurate graphic representation of
features that appear on the Earth’s surface.These features include:
1.Cultural:roads,buildings,urban development,railways,state and
international borders
2.Hydrography:lakes,rivers,streams,swamps and coastal flats
3.Relief:mountains,valleys,hills,contours,cliffs and depression
4.Vegetation:wooded and cleared areas,vineyards and orchards

5. Contour
• An imaginary line on the ground
surface joining the points of
equal elevation is known as
contour.
• The lines are numbered giving
the height above sea level in
meters.
• The process of tracing contour
lines on the surface of the earth
is called Contouring.

6. Characteristics of Contour line
• A contour line is drawn to show places of equal heights.
• Contour lines and their shapes represent the height and slope or
gradient of the landform.
• Closely spaced contours represent steep slopes while widely spaced
contours represent gentle slope.
• Two contours of different elevation usually do not cross each other.

7. Contour Interval
• The vertical distance between
any two consecutive contour
lines is called contour interval.
• The contour interval depends on
the nature of the
ground(i.e.whether flat or steep)

8. Types of slope
Gentle slope:
• When the degree or angle of
slope of a feature is very low,the
slope will be gentle.
• The contours representing this
type of slope are far apart.
Steep slope:
• When the degree or angle of
slope of a feature is high,the
slope will be steep.
• The contours are closely
spaced,they indicate steep
slope.

9. Gentle slope

10. Steep slope:

11. Topographic survey
• Topographic survey is a field of geoscience which deals in the study
and description of surface shape and features of the earth.
Topography in general is related with mapping of the local details
such as relief and natural/artificial features.

12. Types of Landforms
Conical Hill
• A conical hill with uniform
uniform slope and narrow top
represented by concentric
contours,spaced almost at
regualar intervals.

13. Plateau
• A widely stretched flat-topped
high land with relatively steeper
slopes.

14. V – shaped valley
• V – shaped valley occurs in mountainous areas.
• The lowermost part of this valley is shown by the innermost contour
line with small contour interval.
• The contour value increases with uniform intervals for all other
contour lines outward.

15. U-shaped Valley
• A U-shaped valley is formed by strong lateral erosion of glaciers at
high altitudes.The flat wide bottom and steep sides makes it resemble
the letter ‘U’.
• The lowermost part of the U-shaped valley is shown by the innermost
contour line with a wide gap between its two sides.

16. Gradient of Terrain
• Topographic map allows the calculation of the gradient of a terrain.
• This process requires taking the difference in height between two
points and dividing by distance between these points.
• One useful application of this formula is for calculating the flow of a
river down a mountain

17. USE OF TOPOSHEETS IN CIVIL ENGINEERING PROJECTS
1. Toposheet provide valuable information about the topography of
area,whether it is flat,undulating or mountainous.The nature of the
ground surface of an area can be understood by studying topographic
map.
2. By drawing the section in the plan,it is possible to find out profile of
the ground along the line.It helps in finding out depth of cutting and
filling,if formation level of road/railway is decided.
3. The routes of the railway,road,canal or sewer lines can be decided so
as to minimize and balance earthworks.

18. 4. Catchment area and hence quantity of water flow at any point of
river can be found.This study is very important in locating bunds,dams
and also to find out flood levels.
5. From the contours,it is possible to determine the capacity of a
reservoir.

19. DAMS
• A narrow U- shaped valley, i.e., a narrow stream flowing between
high rocky walls, would suggest a concrete flow dam.
• A low plain country, would suggest an earth fill dam with separate
spillways.
• A narrow V-shaped valley indicates the choice of an Arch dam.
• After studying the topography of the site and catchment area, it is
possible to fix the height of the dam and reservoir capacity . Steep
shoulder hills across the rivers may be suitable site for location of the
proposed dam.

21. ROAD ALIGNMENT
• Class and purpose
• Obligatory points
• Gradient
• Horizontal curves
• Obstructions
• Cross drainage works
• Bridges
• Railway crossing
• Agricultural land and dense forests

22. BRIDGE
• Local terrain and site condition
• A straight reach of river.
One cross section each cross the
river at the selected sites can be
taken.
• Catchment area – used mainly
for the flood analysis.

23. BUILDING
• It is very important for the
building site to avoid low-lying
areas with flooding potential.
• Adequate drainage to control
storm water.
• Slope analysis
• Cultural factors
• Natural features

24. TUNNELS
• The underground routes are called tunnels.These are
provided,particularly in hilly regions,to cut down distance and save
time for the traffic.
• The physiography of the area is the first thing to be investigated.It
involves a knowledge of valleys,hills,slopes and other physical
features.This tell about the possible locations for the alignment of
tunnel.

25. RAILWAYS
• Adequate land
• Alignment
• Drainage
• Water supply
• Gradient
• Accessibility

26. CONCLUSION
• A topographic map furnishes information regarding the features of
the ground,whether it is flat,undulating or mountainous.
• A civil engineer studies the contours and find out the nature of the
ground to identify.Suitable site for the project works to be taken up.
• It enables an engineer to approximately select the most economical
or suitable site for an engineering project such as a road, a railway, a
canal or a pipeline etc.
• Catchment area and capacity of a reservoir may be determined from
the contour map.

27. REFERENCE
• D.Venkat Reddy-Engineering Geology-Vikas publishing pvt ltd(page
no:326 – 328)
• Dr.D.S.Arora-Geology For Engineers-Mohindra Capital
Publishers(page no:332-347)
• K.M.Bangar-Principles of Engineering Geology-Standard
Publishers(page no:362-371)
• http://geology.about.com/use of toposheets in civiengineering.htm
• http://en.wikipedia.org/wiki/toposheet