You might be able to come up with some heuristics, but it won't be very useful. Your best heuristic is probably just to take the wave height and compare to the

You might be able to come up with some heuristics, but it won't be very useful. Your best heuristic is probably just to take the wave height and compare to the terrain elevation. Then... add a multiplier. Numerical simulation is your friend here. And... it gets really complex. There are different simplifying assumptions made to make the calculations tenable. Where run-up is a problem, it typically happens where wave interactions or terrain create concentrations of flow and increased wave height. Roughness of the terrain matters too, not just slope. You can probably get pretty close with off-the-shelf software just by doing a 2D HEC-RAS simulation with a terrain DEM and creative boundary conditions to simulate different wave heights, and a small time-step.