  RHIC data on high-$p_T$ hadron production display strong suppression in a
wide rapidity region, indicating strong induced energy loss for both
transversally and longitudinally traveling partons. We investigate the
interplay of energy loss and rapidity dependence in a perturbative QCD improved
parton model, and estimate the opacity of the produced hot matter in $AuAu$
collisions at energies $\sqrt{s}=200$ $A$GeV and 63 $A$GeV at different
rapidity values. Direction-dependent suppression offers the possibility to
study the geometry of the hot matter.
