Meander geometry and skewing patterns suggest mechanical erosion and sediment transport in Venusian canali

Abstract

Canali on Venus bend and curve like rivers on Earth. River meanders, driven by sediment transport, were observed to skew more upstream as their sinuosity increased or as they curved more. We tested whether this relation is observable in canali, which is believed to be formed by carbonatite lava that can thermally erode and carry particulates at the same time. We analyzed 1,555 bends across 45 canali, calculating curvature and using a sinuosity-based window approach to determine canali meander properties. We calculate new flow constraints one to two orders of magnitudes lower than previous bank-full discharge estimates. Canali meander geometry also mirrored terrestrial relationships between meander wavelength λ and radius of curvature r_c (r_c = 0.24λ, R² = 0.87). These two findings support an origin hypothesis that canali were carved by a type of lava capable of mechanical erosion and sediment transport. With this finding, we show that downstream-skewing, observed for Venusian canali (θ̅ = −18.65), may not be an indicator of thermal erosion as suggested in previous studies. Instead, a positive relationship between sinuosity and skewing angle, observed in terrestrial studies and for canali as well (ρ = 0.1671, p ≪ 0.001), may be a signature of mechanical erosion. Although we qualify this last inference due to the low Spearman coefficients obtained, our findings still provide testable hypotheses and approaches for surveys of other solar system channels, while indicating some evidence for a transport-driven meander bend evolution mechanism outside of Earth.