Mass Wasting - The Changing Earth: Exploring Geology and Evolution - page 294

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Figure 11.25 Using Drainpipes to Remove Subsurface Water

Driving drainpipes that are perforated on one side into
a hillside, with the perforated side up, can remove some
subsurface water and help stabilize a hillside.

a

Flow of
groundwater

A drainpipe driven into
the hillside at Point Fermin,
California, helps to reduce the
amount of subsurface water in
these porous beds.

b

b

◗ Figure 11.26 Stabilizing a Hillside by the Cut-and-Fill Method One common method used to help

stabilize a hillside and reduce its slope is the cut-and-fi ll method. Material from the steeper upper
part of the hillside is removed, thereby decreasing the slope angle, and is used to fi ll in the base.
This provides some additional support at the base of the slope.

This material has
been removed

Former
slope

Material from
upper slope
added here

Before After