The Key is in the Bend: How Sinuous Gullies can Improve the Understanding of Their Flow Properties

Details The Key is in the Bend: How Sinuous Gullies can Improve the Understanding of Their Flow Properties The Key is in the Bend: How Sinuous Gullies can Improve the Understanding of Their Flow Properties

Dec 2008

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008agufm.p34a..02m&link_type=abstract

American Geophysical Union, Fall Meeting 2008, abstract #P34A-02

Physics

6017 Erosion And Weathering, 6045 Physics And Chemistry Of Materials, 6055 Surfaces, 6207 Comparative Planetology, 6225 Mars

Scientific paper

Recent gullies are erosional landforms developed on hillslopes in recent Martian time (less than 10 My). The nature of the fluid that created the erosion is still under discussion. On one hand, debris flows containing both liquid water and rocks are frequently invoked, but classic river stream activity dominated by liquid water is also considered. On the other hand, hypotheses invoking only dry granular slides explain many characteristics of the gullies channels, their size, length, presence of levees and terminal deposits. In addition, exotic fluids such as gaseous CO2 flows are still under consideration. The physics of these different fluids can lead to very similar flows, thus, a detailed observation of their morphology is required. For this reason, we have focused our interest to the presence of sinuous gullies, which channels present bends similar to meanders of rivers, with the difference that they occur into a steep slope for a channel, i.e. typically 10 to 20 degrees. The cause of the sinuous shape is usually thought to be due to a perturbation on the flow or a variation of discharge rate. We present models of dry granular flows disturbed on their travel: they display a bend, but no sinuosities are formed subsequently. The sinuous shape over such slopes is typical of a fluid flow that is not reproducible neither in dry granular flows, nor in a classical river stream. Several characteristics can be used to estimate the stream velocity and viscosity from these bends. Especially, the presence of levees that are dissymmetric in the bend is used to measure that the flow is relatively slow (1-3 m/s) with high viscosity (about 10,000 Pa.s). This viscosity is typical of debris flows containing minor proportions of liquid water compared to solid debris, but it is far above the viscosity of river streams, even with high sedimentary flux. In summary, the sinuous shape over slopes higher than 10 degrees requires material consistent with debris flows (rock/water mixture) whereas dry flows or river stream are unlikely. A question still under consideration would be to know if another material such as gaseous CO2 mixtures could mimic these properties or not.

Affiliated with

Also associated with

No associations

Rating

The Key is in the Bend: How Sinuous Gullies can Improve the Understanding of Their Flow Properties does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with The Key is in the Bend: How Sinuous Gullies can Improve the Understanding of Their Flow Properties, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Key is in the Bend: How Sinuous Gullies can Improve the Understanding of Their Flow Properties will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1238081