Solved Topographic Map Worksheet #2 总 B 300 -250- Long Creek ... - Free Printable

Let's solve both problems step by step using the information provided in the topographic map.

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Problem 64: Construct a Topographic Profile Along Line AB

Objective:
Create a cross-sectional profile (topographic profile) along line AB by plotting elevation points where contour lines intersect line AB and connecting them with a smooth curve.

#### Step-by-Step Instructions:

1. Identify Contour Lines Crossing Line AB:
- The contour interval is 10 meters, as stated.
- Starting from point A to B, identify each contour line that crosses the line AB.
- Look at the elevations of these contours.

2. Determine Elevations:
- The lowest visible contour near A is 220 m.
- Then we see: 230, 240, 250, 260, 270, 280, 290, 300, 310, etc., up to the peak at C (around 350 m), then descending again toward B.
- From the map:
- Point A is on the 220 m contour.
- Moving toward C, the contours increase: 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350 (at peak C).
- After C, it descends: 340, 330, 320, 310, 300, 290, 280, 270, 260, 250, 240, 230, 220, and finally reaches B at about 220 m.

3. Measure Distance Along AB:
- The scale bar shows 2 km = 2 cm (assuming standard scale; if not specified, assume the distance from A to B is approximately 2 km).
- So, total length of AB is 2 km.
- Divide this into segments based on where each contour intersects AB.

4. Plot Points on the Profile Grid:
- On the graph labeled "Profile Along Line AB":
- X-axis: Distance from A to B (0 to 2 km)
- Y-axis: Elevation (from 220 to 320 m)

- For each contour line crossing AB:
- Mark a point at the correct distance along AB and the corresponding elevation.
- Example:
- At 0 km (A): 220 m
- At ~0.2 km: 230 m
- At ~0.4 km: 240 m
- ...
- At ~1.0 km: 350 m (peak C)
- Then descending back to B at 2 km: 220 m

5. Connect the Points:
- Draw a smooth, curved line through all the plotted points to represent the terrain profile.

> ⚠️ Note: Since I can't draw directly here, you must do this manually on paper or digitally.

✔ Final Answer for #64:
You will draw a V-shaped profile rising sharply from A to peak C (elevation 350 m at ~1 km), then descending symmetrically back down to B at 220 m. The shape reflects the ridge between two valleys (one being Loop Creek).

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Problem 65: Calculate the Gradient Between C and D

Gradient = (Change in Elevation) / (Horizontal Distance)

#### Step 1: Determine Elevations at Points C and D

- Point C: Located at the summit of the highest closed contour.
- The innermost contour around C is 350 m → so Elevation of C = 350 m

- Point D: Located on the 250 m contour line (just below the 260 m contour).
- So, Elevation of D = 250 m

> 🔍 Note: You can tell D is on the 250 m contour because it lies exactly on that line.

#### Step 2: Measure Horizontal Distance Between C and D

Use the scale bar:
- Scale: 1 cm = 1 km (since 2 km = 2 cm)
- Use a ruler to measure distance from C to D on the map.

From visual inspection:
- C and D are about 1.5 cm apart on the map → so actual distance = 1.5 km

> ✔ You should measure precisely with a ruler, but since this is an estimate from image, let’s assume ~1.5 km.

#### Step 3: Compute Gradient

$$
\text{Gradient} = \frac{\text{Elevation Difference}}{\text{Horizontal Distance}} = \frac{350\,\text{m} - 250\,\text{m}}{1.5\,\text{km}} = \frac{100\,\text{m}}{1.5\,\text{km}}
$$

$$
= 66.67\,\text{m/km}
$$

Or expressed as a ratio:
$$
\frac{100}{1500} = \frac{1}{15} \quad \Rightarrow \quad \text{Gradient} = 1:15
$$

But usually gradient is given in meters per kilometer.

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✔ Final Answers:

#### 64. Topographic Profile
- Plot elevation points along AB starting at 220 m at A, increasing to 350 m at C (~1 km), then decreasing back to 220 m at B.
- Connect with a smooth curve forming a steep V-shape peaking at C.

#### 65. Gradient between C and D
$$
\boxed{66.7} \text{ m/km}
$$
(or approximately 67 m/km)

> ✔️ This means the land drops 66.7 meters per kilometer from C to D.

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Let me know if you'd like a printable version or help drawing the profile!