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LIVE: FINAL EXAM PREPARATION P2 29 OCTOBER 2014

Lesson Description

In this lesson we revise:

The interpretation and analysis of topographic maps

Calculating: o Area o Magnetic Bearing o Grid Reference / Exact Position / Coordinates o Average Gradient o Vertical Exaggeration

Drawing a cross section

Summary

GIS Questions

Know and remember your terminology and concepts.

Always refer to the map and photograph when answering applied GIS questions

GIS questions can bring knowledge about theory on a very elementary level

E.g. the climate of an area (climatology) the general gradient is a gentle slope (geomorphology), the human and social factors of location (settlement) and the economic impacts of development in a specific place (economic geography)

Exam Questions

Refer to the Topographical Map of Parys.

Question 1

Calculate the AREA of Block C2 on the Topographical Map of Parys

Question 2

Calculate the MAGNETIC BEARING of Δ31 [E3] from Δ706 [C2] for the present year

Question 3

Calculate the GRID REFERENCE/EXACT POSITION/ COORDINATES of Δ706 in [C2]

Question 4

4.1 Calculate the Average Gradient between Δ31 [E3] and Δ706 [C2]

4.2 Explain the ratio

4.3 Is this gradient steep or gentle

Question 5

5.1 Draw a Cross Section between point A and point B on the contour sketch map.

5.2 Calculate the Vertical Exaggeration

NB: The vertical exaggeration is the amount by which the vertical scale of a cross section is larger than the horizontal scale

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Answers

Exam Questions

Question 1

Area = Length X Breadth

= (37mm X 0,05) (33mm X 0,05)

= (1.85km) (1.65km)

= 3.05km²

Question 2

True Bearing = 170º SSE

Mean Magnetic Declination (2001) = 23,7º West of True North

Mean Annual Change = 3 ` westwards

Year = 2001

Number of years = 2014 – 2001

= 13 years

Total Change = 13 years X 3 ` westwards

= 39`

= 0º39`

Magnetic Declination (2014) = 23,7º + 0º39`

= 23º42` + 0º 39`

= 23º81`

= 24º21`

Magnetic Bearing = True Bearing + Magnetic Declination

= 170º + 24º21`

= 194º21`

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Question 3

Step 1 – Determine the latitudinal (latitude) coordinates

26º 54` S

Step 2 – Determine the longitudinal (longitude) coordinates

27º 24` E

Step 3 – Calculate the distance and time between the point and the line of latitude directly above

= 23mm X 60``

37mm X 1

= 37 `` ... Latitude is 26º 54`37``S

Step 4 – Calculate the distance and time between the point and the line of longitude directly to the left

= 26mm X 60``

31mm X 1

= 50`` ... Longitude is 27º 24`50``E

Question 4

4.1

Gradient = Vertical Interval

Horizontal elevation/equivalent

Vertical Interval = (Difference in Height between the TWO points)

= 1456, 4m – 1390,1m

= 66,3m

Horizontal elevation/equivalent = (The distance between the TWO points)

= 73 mm X 0.05 (convert to km)

= 3.65 km (convert to m)

= 3650m

Substitute into the formula

= 63,3 63,3

3650 63.3

= 1

57,66

= 1 : 56,66

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4.2 For every 56,66m in horizontal elevation, gradient increases by 1m

4.3 The average gradient is steep

Question 5

5.1

Step 1:

Step 2:

Step 3:

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Step 4:

5.2 VE (Vertical Exaggeration) = VS (Vertical Scale)

HS (Horizontal Scale)

Step 1 – Determine the Vertical Scale

... is the scale on the y- axis

... 1 cm = 40 m

... convert 40m to cm (x 1000)

... the ratio is 1cm: 4000cm

Step 2 – Determine the Horizontal Scale

... is the scale on the x-axis

... 1cm : 50 000 cm

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Substitute into the formula

= 1 : 4000

1 : 50 000

= 1

4000

1

50 000

= 1 50 000

4000 1

= 50 000

4000

= 12,5 times