Question

Difficulty: HardCross-Sections and Intervisibility

A physical geographer constructs a cross-section across a ridge on a topographic map with a scale of 1:250001 : 25{}000. On the vertical axis of the profile, 1 cm1\text{ cm} represents an elevation of 20 metres20\text{ metres}. What is the vertical exaggeration (VEVE) of this cross-section profile?

Answer: 12.5

Answer

The vertical exaggeration of the cross-section profile is 12.5.
To find vertical exaggeration (VEVE), convert both the vertical and horizontal scales to Representative Fractions (RF). The vertical scale of 1 cm=20 m1\text{ cm} = 20\text{ m} converts to 1 cm:2000 cm1\text{ cm} : 2{}000\text{ cm} (1:20001 : 2{}000). The horizontal scale is given as 1:250001 : 25{}000. Dividing the horizontal scale denominator (2500025{}000) by the vertical scale denominator (20002{}000) yields 12.512.5.

Step-by-Step Solution

1
Convert the vertical scale to a unitless Representative Fraction (RF)
Vertical Scale = 1 cm:20 m=1 cm:2000 cm=1:20001\text{ cm} : 20\text{ m} = 1\text{ cm} : 2{}000\text{ cm} = 1 : 2{}000
Both horizontal and vertical scales must be expressed in the same unit (centimetres) to enable direct comparison as representative fractions.
2
State the horizontal scale as a Representative Fraction (RF)
Horizontal Scale = 1:250001 : 25{}000
The map scale provides the horizontal ratio between map distance and ground distance.
3
Apply the vertical exaggeration formula
VE=Vertical Scale (RF)Horizontal Scale (RF)=1/20001/25000=250002000VE = \frac{\text{Vertical Scale (RF)}}{\text{Horizontal Scale (RF)}} = \frac{1 / 2{}000}{1 / 25{}000} = \frac{25{}000}{2{}000}
Vertical exaggeration measures how many times larger the vertical scale is relative to the horizontal scale.
4
Perform the final division
VE=12.5VE = 12.5
Dividing 25,000 by 2,000 yields the unitless exaggeration factor of 12.5.

Key Concept

Vertical Exaggeration of Topographic Profiles
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