Agriculture Reference
In-Depth Information
Fig. 6.3
Schematic of end
area method
A
1
L
A
2
A
n
V
=
L
×
[(
A
1
+
A
2
)/2]
(6.4)
where
volume (m
3
)
V
=
area of the grid square (m
2
)
A
=
distance between cross-section along the baseline (m)
Total volume,
V
T
=
V
i
L
=
Prismoidal Formula
The Prismoidal Formula (PF) allows for greater accuracy than EAM. It is espe-
cially useful when the ground is not uniform or significantly irregular between
cross-sections. PF adds an additional cross-sectional area midway between the two
cross-sections defining the volume being calculated. Note that this cross-section is
calculated separately and is not an average between the two end areas. Volumes are
calculated as follows:
V
=
L
×
[(
A
1
+
(4
×
A
m
)
+
A
2
)
/
6]
(6.5)
where
volume (m
3
)
A
1
,
A
2
=
V
=
areas of the adjacent cross-sections (m
2
)
area of the midway cross-section (m
2
)
A
m
=
=
L
distance between cross-section along the baseline (m)
Contour Area Method
The Contour Area Method (CAM) uses the area of the excavation elevation contour
lines to determine volumes. From a topographic map of the site, the areas enclosed
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