I'm looking for a more or less straightforward (and not very mathematical) way to roughly estimate the flow velocity of a river based on satellite imagery (e.g. Google Earth).
In more detail: I would like to verify data on flow velocity of rivers that has been submitted to me. Usually it was taken at the side of the river (within 2-5 meters of the river bank. What features would I be looking for on Google Earth to get a rough idea if the submitted values could be correct or are completely off the edge? If there is a sandbank or if the river splits I would assume a slower flow velocity and if I can see wave-like turbulences even on satellite imagery or rivers flow together I would expect the flow velocity to increase.
There is no need to calculate an exact velocity, just to get an idea, let's say in the range of +/- 0.5 m/s if submitted values could be correct.
Are there any other signs I should be looking for on the satellite images that could indicate the flow velocity? Does it make sense at all or does it vary too much across small river sections anyway?