KEY WORDS: Kadomtsev-Petviashvili equation, solitons, nonlinear waves, propagation 191 0066-4189/94/0115-0191$05.00 Annu. Rev. Fluid Mech. 1994.26:191-210. Downloaded from www.annualreviews.org by Indiana University -Purdue University Indianapolis -IUPUI on 10/15/12. For personal use only.Quick links to online content Further ANNUAL REVIEWS I According to the terminology adopted here, a wave disturbance is three-dimensional if the associated free-surface displacement varies in both horizontal directions; of course, the corresponding velocity field varies in all three directions. Annu. Rev. Fluid Mech. 1994.26:191-210. Downloaded from www.annualreviews.org by Indiana University -Purdue University Indianapolis -IUPUI on 10/15/12. For personal use only.