Agriculture Reference
In-Depth Information
pedestrian and vehicle movement. We also modify the existing landform to
provide a visual barrier in the form of berms or depressions, or to achieve
some other aesthetic purpose. We use contours and spot elevations to indi-
cate our intended modifications of the existing topography. When we draw
two or more contours, the measured distance between the contours deter-
mines the steepness of the slope. Percent of slope can also be calculated
between two spot elevations. Slope is expressed as a percent, which is the
inclination of the sloping ground plane or embankment. For instance, an
entry walk to a building might be sloped at 2 or 3 percent, which is a com-
fortable slope adequate to direct surface water away from the building. Fig-
ures 9.2-A and 9.2-B provide concrete examples of two slopes (S).
V
V
H
H
Figures 9.2-a and 9.2-B
The angles of the computer screens in the two photographs represent
different slopes. When you want to calculate the slope of a surface, you divide the vertical height V
by the horizontal distance H as in S = V / H.
In Figures 9.2-A and 9.2-B, the computer screen is shown at two dif-
ferent inclinations. The slope of the computer screen relative to the table
in Figure 9.2-A is not as steep as the computer screen slope in Figure 9.2-
B. The slope of the computer screen is labelled S. In grading, slope is
described as a percent that is the relation between the vertical elevation
difference of two points divided by the horizontal distance between the
two points of interest. Referring to Figure 9.3-A, the line labelled V rep-
resents the vertical elevation difference from point b to point a. Line H
is the horizontal distance measured between points c and b. Mathemati-
cally, this relation is expressed in the formula:
S = V / H
