# Rivers and Earth

1. Oct 23, 2016

### jhonn96

1. The problem statement, all variables and given/known data
1) the right bank of rivers and streams is usually eroded their left side in the northern hemisphere and the reverse is observed in the southern hemisphere, why
2) asymmetrical wear on the rails, right in the northern hemisphere and to the left in the southern hemisphere, explain why
3) tropical cyclone swirling in the direction of clockwise in the Southern Hemisphere and counterclockwise in the northern hemisphere, explain why

3. The attempt at a solution
when I searched for an explanation it includes the force of coriolis and deviation for the first two questions but I didn't get a good explanation yet

2. Oct 23, 2016

### haruspex

I have no idea what that means. What is the left side of a right bank? Please check you have quoted this correctly.
Rivers wind about, they are rarely straight. Think about what will happen on different sections, where the river is flowing essentially N, S, E or W.

3. Oct 23, 2016

### CapnGranite

The left and right sides of a river valley are defined by standing in the valley with your back to source/facing the mouth. The right side of the valley is on your right side. I'm not sure that 1.1 is a valid observation. Erosion would be due to stream size, load and other properties of the water flow and also, the composition of the banks--rock and soil types, fractures, etc. The coriolis effect might have an influence, but it's pretty minimal at best. I think in the northern hemisphere, on a river flowing north to south, it's the right bank that might affected. To date, I don't think there have been any credible studies showing any measurable preference to bank erosion due to the coriolis effect.

4. Oct 23, 2016

### CapnGranite

I'm not sure how to go about measuring a coriolis effect in turbulent flow in a meandering stream, given all the variables. The only way it was shown that the coriolis effect affects the flow in a toilet was to construct a perfect container with a perfect drain and wait about half an hour for the coriolis effect to manifest itself on something that small. In a stream the erosion, (re)deposition of material is such that in a given segment of the valley erosion can be modified by something like a log or debris coming to rest and altering the system.

5. Oct 23, 2016

### haruspex

Scanning the net, I see about equal numbers of people who believe it to be an established fact and those who dismiss it as too insignificant.
The latter seems to be the correct view. The erosion pattern is mostly driven by existing meanders. On a left-hand bend, the water is trying to go straight. The water near the bottom is constrained by friction, while the surface water can migrate to the right more freely. That leads to a clockwise gyration, viewed from upstream, and therefore erodes the right-hand bank.
Over time, the bends get more pronounced. Eventually, consecutive bends the same way become such large loops that they meet and short-circuit. The intervening bend the other way then becomes redundant and may form an ox-bow lake (in Australia, a billabong).

6. Oct 23, 2016

### CapnGranite

I think it's true that meander patterns determine the overall erosion pattern for that portion of a river. I was trying to figure out how the coriolis effect could be measured given the more massive erosive powers of "normal" river dynamics. I scanned a few sites, American geophysical Union and Geological Society of America in particular to find any papers that actually measured a coriolis effect in rivers. I couldn't find any.

7. Oct 23, 2016