Pier struck by water: scour and a protective base
A wide, well-founded platform to catch the water that falls back around the pier
A drawing of a pier standing in flowing water accompanies a note on scour and its remedy. Leonardo explains that where the water strikes the pier it rises and gains as much weight as it leaps above the common surface; falling back, it strikes the water below and drives down to the bed, which it continually consumes, hollowing the sides of the struck object. His remedy is a well-founded platform built around the pier, wide enough to catch the water that falls back. A second caption labels the base of the pier.
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Water striking a pier gains weight and scours the bed
Where the water strikes the pier it rises and gains weight equal to how far it leaps above the common surface. Falling back onto the water, it drives down to the bottom, which it continually consumes, so a hollow is scoured along the sides of the struck object.
A wide, well-founded platform around the pier
As a defence Leonardo would build a platform around the pier, well founded and wide enough that the falling water must land upon it, protecting the bed from being hollowed away at the pier's feet.