superimposed drainage[¦sü·pər·im′pōzd ′drā·nij]
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.
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.