For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/science/openSUSE_Tumbleweed/science.repo
zypper refresh
zypper install saga-gis
For openSUSE Factory PowerPC run the following as root:
zypper addrepo https://download.opensuse.org/repositories/science/openSUSE_Factory_PowerPC/science.repo
zypper refresh
zypper install saga-gis
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/science/15.6/science.repo
zypper refresh
zypper install saga-gis
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/science/15.5/science.repo
zypper refresh
zypper install saga-gis