Activity 9.5 Relief and Gradient (Slope) Analysis Date: Name: some friends find a nice place along the Merced River for a picnic. You have a topographic con- the decide to gain a bett map (Fig. A5. tour map (Fig. A9.5.1) better t) in which the index contours are labeled in feet From your resting place at point A. you vantage point by walking up to point B. 6200 8 North 6Merced River C1000 feet Figure A9.5. A Using the labeled
The correct answer and explanation is:
To address Activity 9.5, which involves analyzing relief and gradient (slope) along a topographic map, let’s break down the question.
Resting Point (A) and Elevation Changes
- Resting Point (A): This is where you begin your walk. It’s located near the Merced River, likely on a flat terrain. The topographic map indicates that the contours at this point show an elevation of 1000 feet.
- Walking to Point B: From point A, you walk uphill to point B, located at a higher elevation. Point B’s elevation is marked as 6200 feet on the topographic map.
Gradient (Slope) Calculation
To calculate the slope (also known as the gradient) between two points on a topographic map, we use the formula: Slope (Gradient)=Change in ElevationHorizontal Distance\text{Slope (Gradient)} = \frac{\text{Change in Elevation}}{\text{Horizontal Distance}}
- Change in Elevation: The difference between the elevation at point B (6200 feet) and point A (1000 feet): 6200−1000=5200 feet6200 – 1000 = 5200 \, \text{feet} This is the total vertical change as you walk from point A to point B.
- Horizontal Distance: To calculate the horizontal distance between points A and B, you would measure the distance between the two points along the contour lines on the topographic map. The distance between contour lines represents a specific unit of distance on the map, which can be used to calculate this horizontal distance.
Explanation
- Gradient Interpretation: The gradient represents the steepness of the terrain between the two points. A higher gradient means a steeper slope. In this case, the significant elevation gain of 5200 feet indicates a substantial change in terrain from point A to point B, which could suggest a steep slope if the horizontal distance is relatively short. On the other hand, if the horizontal distance is large, the slope would be more gradual.
- Practical Considerations: Understanding the gradient is crucial for outdoor activities like hiking. Steep gradients would require more energy to climb, while gentler slopes might be easier to navigate. The topographic map helps in identifying areas with steep inclines or flatter terrain, which can be critical for planning a safe and efficient route.
In summary, the relief (elevation change) and gradient analysis between points A and B helps assess the difficulty of the terrain and gives a clearer understanding of the landscape along the Merced River for your picnic spot.