Howland's Theory:
I have a theory to share with you. It is that a slope resembling
a natural curve is more stable than an artificial curve. If we
determine the angle of repose for a particular soil, a Catenary
Curve taken from the midpoint of the slope downward through the
ditchline to the shoulder will be stable. If the same curve is
reversed and extended upward to the feather edge of the cut-slope,
the face of the slope will then be in equilibrium. That convex/
concave slope is what we see in the landscape. If we accept the
definition that the angle of repose is that gradient at which a
particular soil will stand when fully saturated, the slope will
then be in equilibrium. I intend to test the theory to prove its
logic and will tell you the results later.
Therefore, slopes are transitions in elevation. A drop of
rainwater falling at the crest of a convex slope will increase in
velocity as steepness increases. If the lower slope is made concave,
the acceleration will be reduced until the drop of rainwater arrives
at the ditchline.
