We investigate weakly two-dimensional weakly nonlinear weakly dispersi
ve surface waves propagating in a turbulent flow over a gradually slop
ing bottom. The waves are shown to be governed by a turbulently damped
variable-coefficient Kadomtsev-Petviashvili equation with periodic bo
undary conditions. Equations governing the lowest-order mean currents
in both directions as well as the equation describing the lowest-order
mean surface elevation are also derived. Solutions for the wave equat
ion are found numerically using a Fourier pseudospectral technique in
space and finite differencing in the time-like variable.