Meander geometry of Venusian canali: Constraints on flow regime and formation time

Abstract

The similar meander geometries of Venusian canali and terrestrial rivers imply that the in-channel flow regimes may be comparable. This work details meander geometry measurements from ten lowland canali and compares the extensive data set produced to a variety of solar system channels. The meander properties of Venusian canali do not closely match any channel so far observed on the terrestrial planets. However, analysis of the relationship between meander wavelength and radius of channel curvature confirms previous suggestions that the canali were carved by a low (water-like) viscosity fluid. Whether the canali are due to thermal and/or mechanical erosion of the plains by an exotic lava, or have some other genesis, the dominant meander wavelengths of 11 to 77 km require peak fluid discharge rates of up to 6.6 × 106 m3 s-1, an order of magnitude larger than terrestrial rivers. Slight decrease in width along the channel length was observed in most investigated canali, perhaps reflecting the effect of downstream loss processes. Cyclical variations in the average channel width were observed in some channels; where topographic data are available, these variations apparently correlate with peaks in plains topography. This indicates that the canali remained active, after their initially rapid formation, long enough to interact with the early stages of plains tectonism. Copyright 2007 by the American Geophysical Union.