(on maps)
2006-11-05 07:04:27 · 5 answers · asked by Anonymous in Science & Mathematics ➔ Geography
The other answers were correct, however I think you want to know how to convert contours into absolute steepness or a percentage of slope. First, you must be aware that the best you are ever going to do is an approximation, as contour maps are usually approximations of the location of an elevation. That said, to calculate slope, suppose you have a map with a 2inches/mile scale and it takes 1/2 inch to go between 400 foot contours. 1/2 inch = 1/4 mile. Since one mile = 5280 feet, that distance is 5280/4=1320. Now, imagine a right triangle. The upright side is 400, it's vertex of 90 degrees is at an imaginary place in the ground at the same elevation as the lower contour directly below the second (upper) contour where you measured. Thus the two points you measured the distance between now form two sides of an upright triangle. The angled side (c) is 1320. Using trigonometry (either your calculator or a table) you can calculate the length of the third side and the two unknown angles. (boy this is hard without a graph!). The angle where the triangle intersects the lower contour is the angle of the slope - your steepness. Steepness is usually talked of as a "percent slope" which is two times the angle. Why this is I don't know.
I hope you got this complicated little dance. This is actually a real-world application. When the surveyor is going down the road, they are recording angles and slope to convert to absolute (flat) distance. The problem is much the same.
2006-11-05 11:40:57 · answer #1 · answered by gordon B 3 · 0⤊ 0⤋
Each contour line corresponds to a specific elevation. Closeness of contour lines indicate a higher rate of change in elevation, i.e., steepness.
2006-11-05 07:07:55 · answer #2 · answered by arbiter007 6 · 0⤊ 0⤋
As the contour lines get closer together, it means that the elevation is increasing and they are getting steeper. As they get farther apart, it usually means lower elevation and a gentler slope.
2006-11-05 07:09:36 · answer #3 · answered by Kisa 2 · 0⤊ 0⤋
Contour lines denote areas of the same elevation. If the lines are close together, the landscape is steeply sloped. If the lines are far apart, it is flatter or very shallowly sloped.
2006-11-05 07:08:46 · answer #4 · answered by Spaghetti Cat 5 · 0⤊ 0⤋
Each line measures a different height. When they are close together it means the land is changing in height, ie its steep.
2006-11-05 07:07:36 · answer #5 · answered by ? 2 · 0⤊ 0⤋