excellent discussions theo and ewest.
semantically though it still appears in my thick skull like the (ideal) keyway strengthens the ability of the dam to hold back water (increases resistive force), but by itself does nothing to change the force of the water on the dam which is a function of how much water is there and the surface area on which it acts.
so perhaps we are speaking/defining net force....if the resistive force of dam is increased (via having a keyway) the effective or acting hydraulic pressure is reduced even though the absolute hydraulic pressure remains the same....how about that?
sorry, just felt like beating a horse this morning
did we scare off auburnbob?
