CHAPTER 7
SURFACE ARMOR FOR EROSION PROTECTION
In this chapter, descriptive information is generally followed by a discussion of
advantages, disadvantages, typical applications, and design considerations as appropriate. In
order to minimize redundancy, these topics are discussed at the broadest possible level in the
hierarchy of the text; in other words, aspects which are shared by all techniques are discussed
at the beginning of the chapter; aspects which are shared by a group of techniques are
discussed at the group level; aspects that are peculiar to a smaller category of techniques, or
to a single technique, are discussed at the appropriate level of specificity.
The extent of the discussion of specific techniques ranges from the detailed design
guidance presented for riprap to a brief description for some specialized techniques.
Therefore, a complete understanding of a specific technique requires perusal of all material
at a broader level in the text, as well as material peculiar to that technique.
The following paragraphs outline the general description, advantages, disadvantages,
typical applications, and design considerations for most surface armor used in bank
stabilization methods:
Armor is a protective material in direct contact with the streambank. Armor
is often simply called "revetment," but the more specific term "armor" is used
here because other forms of bank stabilization, such as retards and retaining
walls, are also referred to in some regions as revetments. Armor materials can
be categorized as follows:
Stone;
Other self-adjusting armor;
Rigid armor; and
Flexible mattress.
Advantages are: Armoring the surface of the bank is a proven approach which
can be precisely designed for a given situation, and which provides immediate
and effective protection against erosion. Also, existing or potential problems
from erosion by overbank drainage can be effectively addressed integrally with
the design of the streambank armor work.
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