TY - JOUR

T1 - Formation of Mangala Valles outflow channel, Mars: morphological development and water discharge and duration estimates.

AU - Leask, Harald J.

AU - Wilson, Lionel

AU - Mitchell, Karl L.

N1 - Copyright (2007) American Geophysical Union. Further reproduction or electronic distribution is not permitted

PY - 2007

Y1 - 2007

N2 - 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 × 107 m3 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 km3 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 km3. 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 ∼108 m3 s−1, with flow speeds of ∼15 m s−1 and a subcritical Froude number of ∼0.4–0.5.

AB - 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 × 107 m3 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 km3 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 km3. 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 ∼108 m3 s−1, with flow speeds of ∼15 m s−1 and a subcritical Froude number of ∼0.4–0.5.

U2 - 10.1029/2006JE002851

DO - 10.1029/2006JE002851

M3 - Journal article

VL - 112

SP - E08003

JO - Journal of Geophysical Research: Planets

JF - Journal of Geophysical Research: Planets

SN - 2169-9100

ER -