  We show that in stochastic large scale velocity fields superposed on the
general Hubble flow, the formation of the GP-depression in QSO spectra is
intimately related to the formation of the absorption-line structure usually
called `Ly-alpha forest'. Therefore the HI-density in the diffuse IGM might be
substaintially underestimated if one determines the GP-effect from the apparent
continuum in high resolution spectra of QSOs. Our tentative calculations imply
a current baryon density Omega_b h^2_{100} = 0.015 which agrees well with the
baryon density determination from the deuterium abaundance measurement by
Levshakov, Kegel and Takahara (the same volume).
