ABSTRACT
This chapter reviews several alternative bottom protections. Mostly, the increase of strength by means of a bottom protection is the most suitable measure. The main function of a bottom protection is not to prevent scour, but to keep the scour hole at such a distance from the structure, that the risk of falling into its own hole is minimized. For small-scale projects, one should not think of mechanically fabricated bottom protections. Loose rock and/or fascine mattresses will do for many projects. A reason to consider the use of a geotextile in a bottom protection can be that it offers better protection against a sliding scour hole. If a protection consists of loose rock, the scour process can go on after sliding, since the filter structure has been disrupted. A coherent protection can "hang" on the slope, while the filter function remains largely intact.
