superimposed drainage

(hydrology) A naturally evolved drainage system that became established on a preexisting surface, now eroded, and whose course is unrelated to the present underlying geological structure.

A pattern of rivers which have been let down onto a very different underlying structure from the one on which they were formed. Thus, the radiating drainage pattern of the English Lake District is thought to be one formed on a dome which has subsequently been removed by erosion, revealing very different geological structures. Also known as epigenetic drainage; examples include the Bayerische Wald section of the Danube valley in southern Germany.

1. A naturally evolved drainage system having little relation to present geological structure because of erosion occurring after the system’s development.
2. A drainage system purposely designed against existing geological structure.