teoreetiline jõe pikiprofiil, kus sängi igas punktis on erosioon tasakaalus settimisega, продольный профиль русла, выработанный рекой при стабильном базисе эрозии, the longitudinal profile of a graded stream or of one whose smooth gradient at every point is just sufficient to enable the stream to transport the load of sediment made available to it