LAB REPORT
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Abstract
A contour line (often referred to as a "contour") in cartography connects points of equal elevation
(height) above a particular level, such as mean sea level. A contour map, such as a topographic
map, is a map with contour lines that displays valleys and hills, as well as the steepness or softness
of slopes. The grid corners are marked on the ground, and levelling is used to calculate the spot
levels of these comers. The grid is scaled to the map's scale, and the grid corners' spot levels are
input. Interpolation is then used to locate the contours of required values.
In this lab report we will draw contour lines by using square method of contouring for which I
included the lab preparation, procedure and the calculation in the report.
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Contents
Abstract.................................................................................................................................................... 1
Introduction: ........................................................................................................................................... 3
Theory: ..................................................................................................................................................... 3
Pre-lab preparation: ............................................................................................................................... 3
Procedure: ............................................................................................................................................... 3
Skillful Operation: .................................................................................................................................. 4
Safety Procedure: .................................................................................................................................... 4
Results and Discussion: .......................................................................................................................... 4
Conclusion and recommendation: ......................................................................................................... 5
References:............................................................................................................................................... 6
Appendices: ............................................................................................................................................. 6
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Introduction:
Contour lines are extremely useful for determining an area's height. This experiment demonstrates
how to draw contour lines using the square approach.
Theory:
In surveying, contouring is the process of determining the elevation of distinct places on the ground
and placing them in the same horizontal position on a contour map. Vertical control levelling work
is being done while a horizontal control chain survey, compass survey, or plane table survey is
being done at the same time. When using the theodolite, both horizontal and vertical controls may
be accomplished with one instrument. Contouring may be classified into numerous classes
depending on the equipment utilized.
Pre-lab preparation:
o Staff rod
o Pegs
o Theodolite
o Tape
o Auto-level
o Ranging Rods
Procedure:
o First, make a list of all of the items you'll need.
o make temporary modifications (Centering, levelling and focusing).
o Turn on the theodolite and obtain your first reading using the complete circle bearing
method.
o Carry on with the procedure in other areas.
o We'll make a chart once we get enough information on the area.
o We will first compute the highest and lowest contours using the square approach.
o Then we'll go with a contour interval.
o Then, using the square approach, we'll draw the readings as stated in the question.
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Skillful Operation:
o Take careful note of the reading and try to be as accurate as possible.
o Recalculate the readings as needed.
Safety Procedure:
o Handle the equipment with care.
o At least three times, take readings.
o Errors in theodolite must be verified.
o The staff rod must be held upright at all times.
Results and Discussion:
Given Data:
Total Area
= (12×12)m
= 144m2
Area in Grids = 3m
in X-direction
4m
in Y-direction
Top most corner point = 0
Bottom most right corner = +67m
Number of contour = 3 to 7
Highest contour is +2 from right point
From given that:
Highest point = +67m
Assume highest contour = 65m
Last contour = 67 – 65
= +2 m
So from that we can not provide not less than and not more than +2.
Assume contour interval = 10 m
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Number of contour = 65, 55, 45, 35, 25, 15, 5.
Total contour = 7
We use the scale 1:100 in the contour map.
Contour Map
Conclusion and recommendation:
We concluded from the aforementioned findings that contour lines are quite useful in determining
the height of a location.
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My recommendation is to utilize a way other than the square approach. The reason for this is
because while this method is fine, it is not as accurate as other methods. Also, this strategy isn't as
effective as others.
References:
o https://theconstructor.org/surveying/contouring-methods-maps-uses/6451/
o http://ecoursesonline.iasri.res.in
o https://www.engineeringcivil.com
o https://constructionhow.com
Appendices:
Total Area
= 12×12 = 144
Last contour = 67 – 65 = 2
Contour intervals = 65-10 =55
= 55-10 =45
= 45-10 =35
= 35-10 =25
= 25-10 =15
= 15-10 =05