Q. A depressed portion of a land is identified by three closed contours, as shown in the figure below. The area bounded by three contour lines are 6 m2, 24 m2 and 96 m2 respectively. The contour interval is 1 m. Using prismoidal method, the volume of the earth needed to fill the land depression is ________________m3.
A. 66 cubic meter
B. 99 cubic meter
C. 33 cubic meter
D. 9.9 cubic meter
Ans: 9.9 cubic meter
Solution:
The volume of a prismoid is :
V = -1/6(A1 + 4Am + A2)
Where: V = Volume (cubic feet) Am = Middle Area or Area of a plane surface midway between A1 and A2, A1 and A2 are the areas of the end sections. L is distance between top and bottom cross-section.
