Why do some rivers or streams travel in a zigzag pattern when the water can just flow straight?


Why do some rivers or streams travel in a zigzag pattern when the water can just flow straight?

In: Geology

Hills. Easier to go around than through. But eventually given enough time it should work its way to be straight.

[I’m putting this here to show you the first picture](https://cfpub.epa.gov/watertrain/moduleFrame.cfm?parent_object_id=1199)

A variety of different forms of streams exist, and it really comes down to the geology of the stream bed and the slope of the stream. High slope means fast moving waters that can cut through rocks and topsoil with ease, so it makes a straight stream. Stream subtype E is a typical meander stream where you have a narrow channel of slow moving water. In this situation, water is mostly carving away the soil column, not rock. The soil column can be compressed, or boulders can be embedded in them. Hell a deeply rooted tree could cause a meander. When water hits one of these, it starts to form a bend as the water is diverted to the left or right. As the part leading into this bend is straight, the water hits the bend so that the outer edge of the bend has faster running water. This is negligible at first, but over time, the channel deepens and as more water accumulated in the stream and flows down it, the amount and speed of the water on the outer edge starts carving into whatever was there. As the water on the outside edge is fast, the water on the inside edge is slow, and sediments in the water are deposited on the inner edge of the bend. This, over a very long time, leads to the stream channel bending to the left or right.

Also to add on to the other two people, they’re both technically correct. An old stream will meander more, but eventually, the meander becomes so bent that it resembles a Greek omega. At this point the energy of simply hoping the bank is less than the energy needed to take the bend, so it cuts off the meander and becomes a “straight” channel again, creating an oxbow lake

Edit: I should also add that the fast/slow dynamic of one bend gets repeated after the first bend. Basically the fast moving water in the outer edge is still turning hard to the right due to inertia, so even when the stream straightens out after the first bend, it hits the other side of the stream and causes the stream to start bending the other way due to the speed differential

easiest way I can put it.
Water flows through the lowest areas, which are almost never straight.
In the small bends it has it flows a bit slower which causes sedimantation (sand and other small things carried by the water are dropped off)
This changes the flow a bit and causes it to curve a bit more.
Repeat that a few times and you have a meandering river.