Question

Gravity is a very powerful erosional force. This means the steeper a slope is, the more soil will move. A person can calculate how steep a slope is by using the height (rise) divided by the length (run). This answer is then multiplied by 100 to get percent slope. If you had a slope \(15 \mathrm{~m}\) high and \(50 \mathrm{~m}\) long, what would be the percent slope?

Short answer

The slope is 30%.

Step-by-step solution

Identify the Formula

To find the percent slope, use the formula: \( \text{Percent Slope} = \left( \frac{\text{Rise}}{\text{Run}} \right) \times 100 \). Here, "rise" is the height of the slope, and "run" is the length of the slope.

Substitute Known Values

Insert the given values into the formula. The rise is \(15 \text{ m}\) and the run is \(50 \text{ m}\). So, substitute these into the formula: \( \text{Percent Slope} = \left( \frac{15}{50} \right) \times 100 \).

Perform the Division

Calculate the division of the rise by the run: \( \frac{15}{50} = 0.3 \).

Multiply by 100 to Find Percent Slope

Multiply the result from Step 3 by 100 to find the percent slope: \( 0.3 \times 100 = 30 \).

Write the Final Result

Conclude that the percent slope of the given slope is \( 30\% \).

Key concepts

Gravity

Gravity is the force that pulls everything toward the Earth's center. It's the reason things fall when dropped. When it comes to erosion, gravity acts as a driving force that moves soil, rocks, and sediments down a slope. This movement is called mass wasting.
This means that steeper slopes have more gravitational force acting on them, causing more material to move. The power of gravity in erosion depends not only on the slope of the land but also on the amount and type of soil or rock present.

• On gentle slopes, material may creep slowly.
• On steep slopes, landslides or rockfalls may occur.

Understanding gravity's role in erosion can help predict landform changes and manage landscapes more sustainably.

Percent Slope

Percent slope is a way to express the steepness of a slope as a percentage. It's a straightforward method for comparing different slopes or understanding the terrain's inclination. To calculate percent slope, we use the rise, which is the vertical height of the slope, and the run, which is the horizontal distance.
The formula to find the percent slope is: \[ \text{Percent Slope} = \left( \frac{\text{Rise}}{\text{Run}} \right) \times 100 \]This formula helps present the slope in percentage terms, making it easier to understand, especially in fields like construction or landscape design.

• A 0% slope is perfectly flat.
• A 100% slope means the rise equals the run, creating a 45-degree angle.

Slope Calculation

Slope calculation is essential for determining how steep or gentle a slope is. It involves using simple division and multiplication to find the slope percentage. Here's how it works:
1. Identify the 'rise,' which is the vertical increase in height.
2. Identify the 'run,' or the horizontal distance.
3. Use the formula: \[ \frac{\text{Rise}}{\text{Run}} \]This ratio gives a quick understanding of the terrain's steepness. The last step is multiplying the result by 100 to convert it into a percent slope, which communicates the slope's steepness more clearly to non-experts.
Regularly calculating slope is critical in fields from construction to agriculture, where landform management influences decisions.

Soil Movement

Soil movement is a critical aspect of erosion driven by gravity. It refers to how soil particles shift down a slope over time. Several factors affect how and when soil moves:

• Climate: Heavy rain increases water flow, enhancing soil movement.
• Vegetation: Plants and roots can help stabilize the soil, reducing erosion.
• Soil Type: Loose or sandy soil moves more readily than compacted clay or rocky soils.

Human activities like deforestation and construction can accelerate soil movement by removing vegetation or altering natural water paths. Understanding soil movement helps in planning land use and erosion control measures, ensuring soil stays in place to support plant life and maintain landscape stability.