  We estimate the strength of ram pressure stripping (RPS) for HI-rich galaxies
in X-ray detected clusters. We find that galaxies under stronger RPS tend to
show more significantly reduced total HI mass and enhanced central SFR,
compared to control galaxies in the field which have similar stellar mass,
stellar surface density and integral star formation rate. Galaxies under strong
or weak RPS account for around 40% of the HI-rich population at R200, and even
beyond R200 in the most massive clusters. Our results imply the important role
of RPS as a channel of environmental processing far before the galaxies reach
the core region of clusters.
