Branching of Stream Networks

2013 Fall Cyberseminar Series

Presenter(s):
Daniel H. Rothman / Massachusetts Institute of Technology

Talk Description:

The geometric complexity of stream networks has been a source of fascination for centuries. However, a comprehensive understanding of ramification—the mechanism of branching by which such networks grow—remains elusive. Here we show that streams incised by groundwater seepage branch at a characteristic angle of 2 pi / 5 = 72 degrees. Our theory represents streams as a collection of paths growing and bifurcating in a diffusing field. Our observations of nearly 5,000 bifurcated streams growing in a 100 square km groundwater field on the Florida Panhandle yield a mean bifurcation angle of 71.9 ± 0.8 degrees. This good accord between theory and observation suggests that the network geometry is determined by the external flow field but not, as classical theories imply, by the flow within the streams themselves. Joint work with Olivier Devauchelle, Alexander Petroff, and Hansjoerg Seybold

CUAHSI's Fall 2013 Cyberseminar Series on Multidisplinary Approaches to Investigating River Processes!