  The propagation of focused wave groups in intermediate water depth and the
shoaling zone is experimentally and numerically considered in this paper. The
experiments are carried out in a two-dimensional wave flume and wave trains
derived from Pierson-Moskowitz and JONSWAP spectrum are generated. The peak
frequency does not change during the wave train propagation for
Pierson-Moskowitz waves; however, a downshift of this peak is observed for
JONSWAP waves. An energy partitioning is performed in order to track the
spatial evolution of energy. Four energy regions are defined for each spectrum
type. A nonlinear energy transfer between different spectral regions as the
wave train propagates is demonstrated and quantified. Numerical simulations are
conducted using a modified Boussinesq model for long waves in shallow waters of
varying depth. Experimental results are in satisfactory agreement with
numerical predictions, especially in the case of wave trains derived from
JONSWAP spectrum.
