Count the seconds between crests and you have the wave. In deep water the length is gT²/2π and the speed is half of what the crests appear to do; in shallow water the depth takes over entirely and the wave slows, steepens and breaks.
A wave breaks when the water is about 1.3 times its height deep — the ratio varies with the beach slope, but that figure is close enough to find the surf zone on a chart. Everything landward of that line is where the energy is spent.
Waves arriving at an angle push sand along the shore. The rate goes as the wave height to the power of five halves and as the sine of twice the approach angle — so it peaks at forty-five degrees, and a storm moves more sand in a day than a calm month.
K is calibrated, not derived, and different authors give 0.2 to 0.8 for the same coast. Treat the answer as an order of magnitude and use it to compare two directions or two seasons, never as a volume anybody should dredge to.
A beach left alone reaches a shape that dissipates waves with the least work, and that shape is h = A x2/3 — concave up, steep at the top, flattening seaward. The constant A depends only on grain size, which is why coarse beaches are steep.
If the profile keeps its shape and only moves, then a rise in sea level makes the shoreline retreat by the rise times the ratio of the profile's length to its height — typically fifty to a hundred times the rise. It is the simplest possible model and it is wrong in detail everywhere, but the order of magnitude is the point.
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Every one of these has an indicative range — the height band it occupies relative to the tide — and quoting a palaeo-sea-level without it is quoting a number without its error bar. A coral says more than a beach ridge because its range is narrower.
The sand itself — how well sorted, how far it has travelled — is measured in the Loupe, and whether the shoreline you are standing on is rising or drowning is a question for Correlation, where onlap and offlap are the same story at a longer scale.