  The decay of Kadomtsev - Petviashvili lumps is considered for a few typical
dissipations - Rayleigh dissipation, Reynolds dissipation, Landau damping,
Chezy bottom friction, viscous dissipation in the laminar boundary layer, and
radiative losses caused by large-scale dispersion. It is shown that the
straight-line motion of lumps is unstable under the influence of dissipation.
The lump trajectories are calculated for two most typical models of dissipation
- the Rayleigh and Reynolds dissipations. A comparison of analytical results
obtained within the framework of asymptotic theory with the direct numerical
calculations of the Kadomtsev - Petviashvili equation is presented. Good
agreement between the theoretical and numerical results is obtained.
