Agriculture Reference
In-Depth Information
SLope equation: primary tooL for moSt
caLcuLationS required in GradinG
How to calculate slope has been introduced together with several con-
ventions that are familiar to all designers in landscape architecture and
civil engineering, as well as contractors. A complete explanation of how
to calculate slope is presented here.
Slope can be calculated using a simple right triangle equation (see
Figure 9.7). The right triangle equation is written as: S = V / H. S is slope,
and V is the elevation difference from point C to B. H is the horizontal dis-
tance from point A to point B. In the case of Figure 9.7, the incline of the
embankment is sloping at some percent perhaps greater than 50 percent.
V, the elevation or vertical measurement (BC in the figure), is calculated
by subtracting the elevation at the point marked A (the foot, or toe, of the
incline) from the top marked B. If the toe of the incline is 120 feet above sea
level and the elevation at the top of the slope is at the elevation of 132, then
V would equal 12 feet. With a tape measure you could measure H, the hori-
zontal distance from points A and C. If that distance were 15 feet, then you
could calculate for the slope by dividing V by H, and you would have:
S = V / H
S = 12 / 15
S = 0.8 or 80%
80 percent is a steep slope, one that
would be very difficult to climb straight up
from the toe of the slope. A slope of 25 per-
cent is more easily traversed, and certainly
would making mowing the grass much
easier than the slope shown in the Figures
9.7 and 9.8-A and B.
In Figure 9.8, the slope of the embank-
ment can be determined by measuring the
vertical elevation difference from the bot-
tom of the slope to the top, then dividing
B
V
H
S=
S
V
90
C
A
H
Figure 9.7
Right triangle equation
