Re-division of Confluence Patterns of Main Stream and Tributaries of Rivers at Mountainous Area

The current researches on the confluence of main stream and tributaries are carried out from miter-shaped confluence and Y-shaped confluence,which doesn't take the real river pattern into consideration.Therefore,these researches can't express the real characteristics of the river confluence at mountainous river.To solve the problem,the traditional forms of confluence need to be re-divided and studied.A lot of information about natural rivers shows that tributaries at the confluence are almost straight types,while main streams at the confluence are always with the bend,straight,or bifurcation form.So the division of confluence patterns in the light of the river patterns has practical values.