Hydrodynamic forces and surface topography: Centimeter-scale spatial variation in wave forces

We measured the variability in hydrodynamic forces among locations separated by only centimeters along three horizontal transects on a steep rocky shore. Our results extend previous work showing that wave forces have the characteristics of 1/f-noise, in which variability in wave forces decreases exponentially with decreasing scales of measurement. Furthermore, our results suggest that protection from hydrodynamic forces is not a certain consequence of a rugose substratum, suggesting that investigators should directly test (rather than assume) smallscale topographic protection from hydrodynamic forces.