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How Aeolian-Fluvial Interactions Shape the Surface of Titan

Presentation #205.02 in the session Titan IV: Surface and Interior (Poster + Lightning Talk)

Published onOct 23, 2023
How Aeolian-Fluvial Interactions Shape the Surface of Titan

Evidence for both fluvial and aeolian surface processes have been observed on Titan. Methane precipitation feeds fluvial landforms (FLs), 50% of which exhibit rectangular drainage patterns (a much rarer pattern on Earth typically due to conjugate faulting). Methane rivers are likely episodically active since rainfall, concentrated at the poles, lasts 10-100 hours each Titan year (30 Earth years). Mid-latitude precipitation is limited, however, FLs have been observed in these regions. Linear dune fields cover 17% of Titan’s surface, mostly in equatorial latitudes. They are potentially composed of hydrocarbon and nitrile sand-sized particles precipitated from atmospheric photochemical reactions. Limited data availability means modelling is one of the best methods to understand active and previously active processes on Titan. Here we report the pilot study by the Working group on Aeolian-Fluvial Terrain Interactions (WAFTI), based at the European Space Agency, which examines the effects of these processes in synergy under Titan conditions, using a combination of modelling and geomorphological analysis. We developed the Titan Aeolian-Fluvial Interactions model to simulate interacting fluvial and aeolian processes on Titan. This is a landscape evolution model based on a coupled implementation of the Caesar-Lisflood fluvial model, and Discrete ECogeomorphic AeolianLandscape model (DECAL) dunes model. The Caesar-Lisflood fluvial model routes water over a digital elevation model and calculates erosion and deposition from fluvial and slope processes and changes elevations accordingly. The DECAL model is based on the Werner slab model of dunes, which simulates dune field development through self-organization. Our results show that although Titan dunes are potentially inactive, they are so much larger relative to rivers that dunes represent major topographic obstacles to rivers. Much like on Earth, we found that the nature of dune-river interactions are dependent on the relative orientations of dune crestlines and the river channel. In some cases, where the river ran semi-parallel to dune crests, the river could be funnelled upslope along interdune coridoors, forming rectangular drainage patterns. In other cases when the relative orientations were not parallel, the river would pool and then breach the lower area of a dune crest and flood deeper into the dune field, delivering sediment in the process. These findings help our understanding of FL drainage patterns, distribution, and planforms, and suggest a mechanism for fluvial sediment delivery into dune fields.

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