Question

Difficulty: EasySlope and Gradient Calculation

Match each set of topographic relief measurements to its corresponding slope gradient ratio (1 in N1 \text{ in } N).

  • Vertical Interval of 20 m20\text{ m} across a Horizontal Distance of 200 m200\text{ m}1 in 101 \text{ in } 10
  • Vertical Interval of 50 m50\text{ m} across a Horizontal Distance of 1,000 m1,000\text{ m}1 in 201 \text{ in } 20
  • Vertical Interval of 100 m100\text{ m} across a Horizontal Distance of 500 m500\text{ m}1 in 51 \text{ in } 5
  • Vertical Interval of 10 m10\text{ m} across a Horizontal Distance of 500 m500\text{ m}1 in 501 \text{ in } 50

Answer

Vertical Interval 20 m20\text{ m} / Distance 200 m200\text{ m} matches 1 in 101 \text{ in } 10; Vertical Interval 50 m50\text{ m} / Distance 1,000 m1,000\text{ m} matches 1 in 201 \text{ in } 20; Vertical Interval 100 m100\text{ m} / Distance 500 m500\text{ m} matches 1 in 51 \text{ in } 5; Vertical Interval 10 m10\text{ m} / Distance 500 m500\text{ m} matches 1 in 501 \text{ in } 50.
Each slope measurement set correctly matches its calculated gradient ratio by applying the standard formula Gradient=VIHE\text{Gradient} = \frac{\text{VI}}{\text{HE}} and reducing the resulting fraction to a 1 in N1 \text{ in } N form.

Step-by-Step Solution

1
Recall the fundamental gradient formula
Gradient = Vertical Interval (VI)Horizontal Equivalent (HE)\frac{\text{Vertical Interval (VI)}}{\text{Horizontal Equivalent (HE)}}
Gradient measures the ratio of vertical elevation change to horizontal ground distance.
2
Calculate the ratio for the first measurement set (20 m20\text{ m} VI and 200 m200\text{ m} HE)
20200=110=1 in 10\frac{20}{200} = \frac{1}{10} = 1 \text{ in } 10
Dividing both numerator and denominator by 20 simplifies the fraction to 1 in 10.
3
Calculate the ratio for the second measurement set (50 m50\text{ m} VI and 1,000 m1,000\text{ m} HE)
501000=120=1 in 20\frac{50}{1000} = \frac{1}{20} = 1 \text{ in } 20
Dividing both numerator and denominator by 50 simplifies the fraction to 1 in 20.
4
Calculate the ratio for the third measurement set (100 m100\text{ m} VI and 500 m500\text{ m} HE)
100500=15=1 in 5\frac{100}{500} = \frac{1}{5} = 1 \text{ in } 5
Dividing both numerator and denominator by 100 simplifies the fraction to 1 in 5.
5
Calculate the ratio for the fourth measurement set (10 m10\text{ m} VI and 500 m500\text{ m} HE)
10500=150=1 in 50\frac{10}{500} = \frac{1}{50} = 1 \text{ in } 50
Dividing both numerator and denominator by 10 simplifies the fraction to 1 in 50.

Key Concept

Slope and Gradient Calculation
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