Pressurized groundwater outflow experiments and numerical modeling for outflow channels on Mars

Marra, Wouter A.; Hauber, Ernst; McLelland, Stuart J.; Murphy, Brendan J.; Parsons, Daniel R.; Conway, Susan J.; Roda, Manuel; Govers, Rob; Kleinhans, Maarten G.

Abstract

© 2014. American Geophysical Union. All Rights Reserved. The landscape of Mars shows incised channels that often appear abruptly in the landscape, suggesting a groundwater source. However, groundwater outflow processes are unable to explain the reconstructed peak discharges of the largest outflow channels based on their morphology. Therefore, there is a disconnect between groundwater outflow processes and the resulting morphology. Using a combined approach with experiments and numerical modeling, we examine outflow processes that result from pressurized groundwater. We use a large sandbox flume, where we apply a range of groundwater pressures at the base of a layer of sediment. Our experiments show that different pressures result in distinct outflow processes and resulting morphologies. Low groundwater pressure results in seepage, forming a shallow surface lake and a channel when the lake overflows. At intermediate groundwater pressures, fissures form and groundwater flows out more rapidly. At even higher pressures, the groundwater initially collects in a subsurface reservoir that grows due to flexural deformation of the surface. When this reservoir collapses, a large volume of water is released to the surface. We numerically model the ability of these processes to produce floods on Mars and compare the results to discharge estimates based on previous morphological studies. We show that groundwater seepage and fissure outflow are insufficient to explain the formation of large outflow channels from a single event. Instead, formation of a flexure-induced subsurface reservoir and subsequent collapse generates large floods that can explain the observed morphologies of the largest outflow channels on Mars and their source areas.

Citation

Marra, W. A., Hauber, E., McLelland, S. J., Murphy, B. J., Parsons, D. R., Conway, S. J., …Kleinhans, M. G. (2014). Pressurized groundwater outflow experiments and numerical modeling for outflow channels on Mars. Journal of Geophysical Research: Planets, 119(12), 2668-2693. https://doi.org/10.1002/2014JE004701

• Acceptance Date: Nov 21, 2014
• Online Publication Date: Nov 26, 2014
• Publication Date: 2014-12
• Deposit Date: Dec 22, 2016
• Publicly Available Date: Dec 22, 2016
• Journal: Journal of geophysical research : planets
• Print ISSN: 2169-9097
• Electronic ISSN: 2169-9100
• Publisher: American Geophysical Union
• Peer Reviewed: Peer Reviewed
• Volume: 119
• Issue: 12
• Pages: 2668-2693
• DOI: https://doi.org/10.1002/2014JE004701
• Keywords: Mars; Fluvial processes; Groundwater; Hydrology; Experiments; Outflow channels
• Public URL: https://hull-repository.worktribe.com/output/446666
• Publisher URL: http://onlinelibrary.wiley.com/doi/10.1002/2014JE004701/abstract
• Additional Information: This is the author's accepted manuscript of an article published in: Journal of geophysical research : planets, 2014, v.119 issue 12.