Evolution of a nonlinear wave field along a laboratory tank is studied experimentally
and numerically. The numerical study is based on the Zakharov nonlinear equation,
which is modified to describe slow spatial evolution of unidirectional waves as they
move along the tank. Groups with various initial shapes, amplitudes and spectral
contents are studied. It is demonstrated that the applied theoretical model, which
does not impose any constraints on the spectral width, is capable of describing
accurately, both qualitatively and quantitatively, the slow spatial variation of the
group envelopes. The theoretical model also describes accurately the variation along
the tank of the spectral shapes, including free wave components and the bound waves.