VARIATIONS IN PALEO-DISCHARGE ESTIMATES WITHIN MARTIAN OUTBURST CHANNELS

This study identifies the magnitude of variations in estimated paleo-discharge (Q) in Martian outburst channels using several methodologies. The Darcy-Weisbach (D-W) method provides the most consistent appraisal. Q estimates of Martian outburst channels within in several regions have been measured since the early 1970s using various methodologies. These include applying different versions of the Manning (M) and Chezy (C) equations or the Darcy-Weisbach (D-W) friction factor. Image analyses have also been carried out on various visible and infrared data from the Mars Reconnaissance Orbiter HiRISE instrument and other orbiting satellites.

Here we compare the Q estimates produced by various approaches. This was achieved by focusing on values of channel roughness. Additional examined parameters include estimates of length, width, flow depth and velocity, slope, radius and cross-sectional area used in the flow reconstructions. The correlation coefficient between Q and cross-sectional area (r2=0.74) shows the strongest relationship. Conversely, the correlation coefficient between Q and radius (r2<0.01) and Q and slope (r2<0.01) shows no relationship. Future research will focus on determining envelope curves for each of the parameters listed above. These curves may aid ongoing efforts to constrain paleo-discharge estimations on Mars.

Our results also indicate that differentiated terrain (i.e. volcanic, eolian, fluvial), is related to the volume of discharge in paleo-channels and the resulting correlation coefficients based on paleo-channel geometry as well as the geologic epoch of the terrain in which these channels developed: Noachian, Hesperian, Amazonian. Preliminary analyses show that the most constrained estimates occur within the Martian cratered plains, and channel and canyon materials due to their partially buried, fractured, or brecciated nature.