Junction angles in drainage networks

A theoretical model relating the junction angle of a tributary in a drainage network to its own Shreve magnitude and the Shreve magnitude of the stream into which it flows is developed and verified using published data (including Landsat maps) on U.S. networks with different underlying rock types, relief, and basin lengths. Good agreement is found, and a tendency for the slopes of individual network links to evolve toward graded longitudinal profiles as the network approaches an equilibrium (graded') planimetric pattern is noted. The differences between the network patterns predicted by the model and those observed on Mars are indicated, confirming the results of Pieri (1979, 1980).