title: Ramification of stream networks.
abstract: 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 2π/5 = 72°. 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 km(2) groundwater field on the Florida Panhandle yield a mean bifurcation angle of 71.9° ± 0.8°. 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.
authors.affiliation: Lorenz Center and Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Olivier
authors.initials: O
authors.lastname: Devauchelle
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Petroff
authors.forename: Hansjörg F
authors.initials: HF
authors.lastname: Seybold
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Rothman
mesh_terms: D003247:Conservation of Natural Resources / Q000379:methods*; D004784:Environmental Monitoring / Q000379:methods; D052918:Environmental Restoration and Remediation / Q000379:methods*; D005431:Florida; D005843:Geography; D015233:Models, Statistical; D008962:Models, Theoretical; D045483:Rivers; D014872:Water Movements