Question

Constructing a Topographic Map 7.7 Construct a simple topographic map by drawing contour lines. Early topographic maps were constructed by first surveying an area and establishing the elevations at numerous locations. The surveyor then sketched contour lines on the map by estimating their position between the points of known elevation Today, topographic maps are made by computers from radar data or a series of stereoscopic aerial photographs similar to those in Figure 7.2. The data from these images is processed by computers that are programmed to construct topographic maps. However, considerable field work is necessary to establish elevations and eliminate computational errors. ACTIVITY 7.7 Constructing a Topographic Map The process of constructing a simple topographic map will prove useful in future labs, when you will be asked to interpret landforms on topographic maps. 1. Use the elevations in Figure 7.12 as a guide for drawing contour lines. The 100-foot contour line is provided for reference. Using a 20-foot contour interval, use a pencil to draw a contour line for each 20-foot change in eleva- tion below and above 100 feet (e.g., 60 feet, 80 feet, 120 feet). You will have to estimate the elevations between the points. Label each contour line with its elevation. 2. Does the land shown on the topographic map you constructed generally slope downward toward the north or south? Land slopes downward toward the 3. Show the direction each stream is flowing by drawing arrows on the map. Exercise Seven / Aerial Photographs, Satellite Images, and Topographic 1 Figure 7 Constructi 158 152 120 163 130 155 131 125 139 125. 120 110 112 80 118 110 79 63 83 65 .73 1S .142 ,57 59 124 78 120 87° 60 50

Answer 1

Ans.

Before answer the question, we must know that the contour lines are the lines joining the points of equal elevation. Here also I will try to map the point with same elevation.

152 120 140 163 130 155 .131 125 139 125. 120 110 112 80 118 140 110 79* 63 83 65 73 118 . 142 。57 59 24 78 , 120 87° 120 80 60 20 60 80

Here I have taken the contour interval of 20 feet which is written with brown color.

Ans. 2

Yes the land is sloping from north to south (towards south) as we can see from the map above.

Ans. 3

In the below figure, the arrows show the direction of stream that follows the pattern of slope of the topography and it is to some extent, a dendritic pattern.

152 120 140 163 130 155 .131 125 139 120 125. 110 112 80 118 140 110 79 83 65 73 118 . 142 。57 59 24 78 , 120. 87° 120 80 60 20 60 80

I hope the answer is clear to you now, If you have any further query, please leave a comment, I will try my best to solve it for you. Goodluck