Hydrological modeling of outflow channels and chaos regions on Mars

Jeffrey C. Andrews-Hanna, Roger J. Phillips

Research output: Contribution to journalArticlepeer-review

108 Scopus citations


The Martian outflow channels were carved by the eruption of catastrophic floods from groundwater aquifers. This study models the time evolution of a typical outflow channel flood originating within a chaos region. The flood initiates when superlithostatic pore pressures within a confined aquifer lead to the propagation of hydrofractures through the confining cryosphere to the surface. The peak discharges are modulated by diffusion of the flood pulse within the chaos region, resulting in a rapid rise in discharge immediately after flood initiation. Later flow is limited by diffusion through the aquifer and is sensitive to the variation of the hydraulic properties with changing pore pressure. After the termination of the flood by freezing within the chaos region much of the aquifer remains pressurized. Diffusion of the excess pressure from the undrained portions of the aquifer back toward the chaos region triggers a second flood, ultimately resulting in a periodic series of floods. For Iani Chaos at the source of Ares Valles, modeled peak discharges on the order of 106 to 107 m3 s-1 were obtained, with total volumes of individual floods ranging from 600 to 5000 km3 and a minimum period between successive floods of ∼44 years. The cumulative flood volume depends upon the number of floods, which is a function of the volume of pressurized aquifer or the duration of recharge from distant sources. These results suggest that individual channels were likely carved by large numbers of floods and were unlikely to have experienced bankfull flow in their final state.

Original languageEnglish (US)
Article numberE08001
JournalJournal of Geophysical Research: Planets
Issue number8
StatePublished - Aug 20 2007
Externally publishedYes

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Atmospheric Science
  • Astronomy and Astrophysics
  • Oceanography


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