Abstract
A time-dependent wave equation is developed for waves propagating over a porous rippled layer, with rapid undulations about the mean depth satisfying the mild slope assumption, on an impermeable slowly varying depth also satisfying the mild slope assumption. The ripples are assumed to have wavelengths of the same order as those of surface gravity waves. The equation developed here contains the existing theories of Berkhoff (1972) and Kirby (1986). The rates of both reflection and transmission over porous rippled beds become smaller than those over impermeable rippled beds, due to the energy dissipation in porous layer.
