Backgarden River Channel Formation

This may well get a nomination as the most boring video ever – it shows almost nothing happening except a few grains of sand being moved down a slope. But in doing so, it has formed this hugely complex series of river channels and I’m impressed with it.
The next one [still uploading – and will post when done] is from an earlier stage when more is happening and shows a river valley actually forming in my back garden. So hopefully, those who don’t appreciate trying to see grains of sand moving will find it more interesting.

Above shows the experimental river channel. The channel is fed by a constant flow which feeds into a tipping bucket which pulses the water. The video starts at a bend showing how the changing water level changes the part of the channel holding the flow and how the sediment is moved. it then goes to the corner when the flow is diverted out. Next we have a braided section where the stream spreads out and has many small islands, and finally a delta, where if you look carefully you can see the sediment being swept into the water where it creates sharp edge as the sediment settles out.
For info, the video was taken in my back garden. All “debris” such as leaves is natural – and so I’ve left it in because debris is an important factor causing pool formation and diverting flow.

This is a longer video. Hence I suggest watching the above speeded up version. It shows the start of my experimental setup with a massive bulk of sand at one end. I start with a constant flow of water. Very quickly the water eats down into the sand creating a deep gorge. I presume at some critical slope, the gorge then starts widening undermining the sides causing multiple collapses and a debris flow with a very characteristic fluvial fan. These are just the kinds of features one sees in places like Glen Coe so I’m really impressed. Eventually it starts settling down and a kind of “upland” river valley is formed with a V shaped valley and a meandering river occupying the base.