Infragravity (IG) waves are long waves whose frequency ranges between 0.005 Hz to 0.04 Hz. The directional properties of IG waves are essential in various engineering fields, but few spectra reconstruction methods have been tested to be robust for the last forty years. In this study, artificial wave signals were created to check the accuracy and reliability of several wave spectra reconstruction methods. These data were designed as if produced from the REFLEX field measurements. Three commonly used conventional directional wave spectra reconstruction methods, EMEP, IMLM and BDM, are applied and compared over Sea-swell (SS) wave field and IG+SS wave field.

Though the existence of bound IG waves weakens the accuracy and reliability of these methods, they may be used to reconstruct the IG wave spectra with reasonable results. It is found that the EMEP outperforms the BDM and the IMLM since it yields accurate results with low sensitivity to noise in most cases. The BDM is reliable in moderate wave conditions, but would fail in case of high wave height or narrow directional spreading. The IMLM tends to produce less accurate results than the EMEP. The EMEP is recommended because of its overall reliability and low sensitivity.