River erosion baselevel

It refers to the level under which the down-cutting erosion of river is disappeared, including two types: ultimate baselevel and local (regional) baselevel.

For the rivers emptying into the sea, sea level and the level extending from the sea level into the continent are ultimate baselevels.

For individual reaches, local baselevel is hard rock step, lake and depression or junction of tributaries. For instance, Yachihe River in the Park converged by Liuchonghe River and Sanchahe River is local baselevel.