Figure 1-9. Delineation of roads or runways
STRIPPER METHOD
The Stripper Method, illustrated in figure 1-10, page 1-14, is a variation of the Geometric Shapes Method.
Approximate the watershed area by drawing a series of lines an equal distance apart. Then approximate the area
by a number of trapezoids with the first and last segments approximating triangles. The heights of all these
trapezoids are identical. The total area of all the trapezoids may then be expressed by the following formula:
NOTE:
A map of the drainage area and a ruler will be needed.
A = Area
b = base
h = height
A = 1/2h(b1) + 1/2h (b1 + b2) + 1/2h (b2 + b3) + 1/2h (b3 + b4)...+ 1/2h (b8)
This may be factored and reduced to the following:
A = 1/2h (bl + b1 + b2 + b2+ b3 + b3 + b4 + ...b8)
Which simplifies to:
A = h (b1 + b2 + b3 + b4 + ...b8) + h(bi) (or the sum of all the bases)
Using the Stripper Method, measure (graphically) each base, take the sum, and multiply by the height (the
perpendicular distance between any pair of bases, which is a constant). The distance between the parallel lines
may be any value but must be constant throughout the
1-13
EN5465
Previous Page
