Open AccessFormation of Mangala Valles outflow channel, Mars: Morphological development and water discharge and duration estimates
Author(s) -
Leask Harald J.,
Wilson Lionel,
Mitchell Karl L.
Publication year - 2007
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2006je002851
Subject(s) - froude number , volume (thermodynamics) , geology , sediment , channel (broadcasting) , hydrology (agriculture) , erosion , outflow , mars exploration program , geomorphology , flow (mathematics) , mechanics , oceanography , geotechnical engineering , physics , engineering , quantum mechanics , astronomy , electrical engineering
The morphology of features on the floor of the Mangala Valles suggests that the channel system was not bank‐full for most of the duration of its formation by water being released from its source, the Mangala Fossa graben. For an estimated typical 50 m water depth, local slopes of sin α = ∼0.002 imply a discharge of ∼1 × 10 7 m 3 s −1 , a water flow speed of ∼9 m s −1 , and a subcritical Froude number of ∼0.7–0.8. For a range of published estimates of the volume of material eroded from the channel system this implies a duration of ∼17 days if the sediment carrying capacity of the ∼15,000 km 3 of water involved had been 40% by volume. If the sediment load had been 20% by volume, the duration would have been ∼46 days and the water volume required would have been ∼40,000 km 3 . Implied bed erosion rates lie in the range ∼1 to ∼12 m/day. If the system had been bank‐full during the early stages of channel development the discharge could have been up to ∼10 8 m 3 s −1 , with flow speeds of ∼15 m s −1 and a subcritical Froude number of ∼0.4–0.5.