Latin word riparius comes from Proto-Indo-European *(o)reyǝ-, and later Latin ripa (Bank (of a river). Shore (of the sea).)

Detailed word origin of riparius

Dictionary entry	Language	Definition
*(o)reyǝ-	Proto-Indo-European (ine-pro)
ripa	Latin (lat)	Bank (of a river). Shore (of the sea).
riparius	Latin (lat)	That inhabits the banks of rivers; riparian.