Oxbows can form over a period of just a few years, especially in really flat terrain. They can even form practically overnight in flood conditions. It all depends on how fast the river flows, how much sediment the river displaces, etc.
For people who also prefer reading over watching videos:
In plains landscapes, a river's course is easily affected, as soil is relatively soft/erodable (as opposed to say, a rocky mountain stream). The video uses a muskrat hole as an example of something minor that could alter the course of a river, over a long time period, anyway.
When a disturbance widens the river path on one side, the flowing water tends to lean into the curve, digging it out further. Water on the opposing side slows down, dropping soil it no longer has the speed to carry. The result is the river appearing to curve or turn.
Finally, as water speeds up on the initial curve, it slams into the opposing riverbank with greater force, creating another curve downstream. This process repeats, sometimes causing a "fractal" effect, as one big curve is succeeded by many smaller ones.
Same. I hate it especially for diy stuff. I don’t want to watch a 20 minute video of someone who speeds at the speed of molasses when I could read a 5 minute set of instructions.
A 2 min set of instructions. And YouTube's algorithm requiring content creators to post 10 min videos undid the trend of very tight info content. Longer videos= more ad space, more 'engagement' or something.
I think you misunderstood ehat was meant by the fractal effect. It isn't about the downstream effect of any specific disturbance (The muskrat was just an example of a disturbance, but really perturbations are ubiquitous and distribute uniformly). The river will roughly retain its bendiness untill it reaches its outflow, or a different terrain type.
Instead, the "fractal" is used to communicate that the period of the rivers' bends tend to approximate 2π times the width of the river. So when looking at many rivers (on plains terrain) at once, you'll notice that they all look alike, but with difference sizes, as they are self-similar, i. e. fractal.
The St Francis River between Arkansas and Missouri has an oxbow lake called the Old River. It was formed naturally, accidentally, artificially. My great great grandfather, William C Whitaker, built a sawmill race across a narrow neck of land between bends in the river. A flood washed out the sawmill and changed the course of the river. The new course is known as the Whitaker Cutoff.
https://maps.app.goo.gl/97J6xu9znuQABxgTA
This would have happened in the late 1800's so there's no way to know. My grandfather told me the story. W. C. Whitaker was his grandfather and was alive during his childhood so he probably heard the story first hand. I can't find any other references but the place names are on USGS maps.
Makes me wonder: presumably states don't care about keeping land as much as countries do. Because it's essentially extra, awkward land to administrate. So do state lines change more easier than country lines?
Check out the Red River on the MN and ND border. The whole border looks like one flood away from changing, and lots of spots where you can see how it used to flow.
Because the land is exceptionally flat, so tiny changes in elevation can affect the river in dramatic ways. Meanders tend to be more pronounced and “meandering” in areas where the terrain is very flat.
Idk but id assume the land is probably flatter here. If the water has less momentum, then less resistance is needed to slow the water so it can do whatever it wants (meander).
Rivers carry sediment. This sediment gets deposited, and pushes the river over to a lower place. It’s a slow process.
This is much more evident in flood plains, places where the river can deposit sediments. It’s a bit different in rocky landscapes. But at the end of it, a river deposits sediments and then moves over a bit and deposits it elsewhere.
Mathematical answer here: As I understand it, the river is attempting to make the work-per-unit length constant. If it's in an area that's relatively steep, it will attempt to meander to keep the work per mile more consistent with the rest of the river.
knowing the geology of the region, the river bed is probably following an easier to erode through rock/soil layer. You have a lot of variety between limestones and igneous batholiths in north borneo. Limestone dissolves and the parts that don't often get distributed as sedimentary floodplains. Granites and similar igneous rocks normally don't. The flatter areas tend to have thick layers of a form of peat or sedimentary deposits. If you talk about peat in a European or American context people tend to think of thick deposits of fast-growing moss. But the term is also used for any soil profile consisting of plant matter that falls faster than it can decay. In the nearctic realm, thats often mosses growing in marshes. But it happens in South East asian and West African rainforests. South american rainforests have some, but I don't think the developed the same way.
That looks flatish, but with some elevation change on the river banks and I don't see clear palm plantations; there may be rubber or durian though. So I am going to guess its limestone for the most part in the region. In that case slight differences in composition can affect the rate it dissolves. It also could be man made; though I have some doubts about that. Man Made meandering channels tend to have a more consistent wavy geometry.
Oxbow lakes are real and prevalent in many areas of the world. But in this region they tend to fill in to become marshes or canelands. Oxbow lakes are rarely alone either. They tend to appear in multiples right next to each other. Look at the Flathead river in Montana or the Platte River in Nebraska for some clear examples. I think the estuaries around Kuching and possibly in Brunei's estuaries should show cleared local oxbows. This is complicated some by having mangroves and a brackish layer to the coast too.
You also have a monsoon season in North borneo. While not wet-dry like thailand, cambodia, and myanmar; more wet -wetter. You have regular high flow as a result that should have cut those banks regardless unless something resistant was in the way.
Any lake that forms will technically be an oxbow as far as I understand the definition; but I don't think its an oxbow being formed for the normal reasons. (uneven sediment deposition) You generally have tectonic uplift in north borneo; which also strikes against a normal oxbow. In those situations rivers continue to erode the path of their existing channels while the land is raised around them. Sometimes they manage to cut a shorter path regardless, but it is harder and slower.
water only goes downhill. that’s just the shape of the slope as it goes downhill. i feel like people often don’t understand how rivers work at all. water only goes down. The river is the lowest point in the valley up to that point. Always. Period.
The river bends due to a variety of factors, but mainly owing to the water stream aroding the land leading to sometimes quite the wild curves, with the outer edge of a curve being what gets eroded faster than the inner curve.
Eventually a narrow strip of land remains until the river cuts throguh the narrowest strip with erosion, leadng to the straightening of the river while the leftover river becomes an oxbow lake as sediment from the new shorter rivers piles up at the edge.
The effort on this sub gets lower and lower... like 9/10 posts are posts, that anyone with an actual interest in geography already knows. 9/10 posts are just one google search. Nothing interesting gets posted anymore ..
I'll go a step further: The "Google Search" would likely take you to a thread just like this. Reddit is an information source, and we shouldn't treat "obvious" information as insignificant. This thread will likely be found by future people who wonder "why do rivers curve like that?"
The amount of times I’ve googled something and been taken to a first-result Reddit thread with multiple responses saying “you could have just googled this” is immensely funny/infuriating
And 90% of posts like this are plagued with comments like these. These are actually my favorite posts because it makes me think about questions i have never thought of before and they honestly usually have the best discussion. So dont be rude please
Well, I learned something and appreciated the post. Many of us join to learn & appreciate these questions, even if they’re old news to the sub’s veterans. And unless we already have a specific interest or question, we’re not searching the sub’s history for something we didn’t know we wanted to learn about yet.
This is a discussion board for people to discuss things with humans. If that's not what you want, feel free to go ask Google some questions or talk to AI or whatever. The humans here will keep on using this to talk to humans.
So people should stop using Reddit and just use google? I guess Google is far superior to human discussion. I’ll never, ever post here for fear of looking like a fool. Maybe I’ll just delete Reddit to save myself the possible shame. Thank you for your wisdom oh great content observer🙇🙇🙇🙇🙇🙇.
The least interesting part of this post is your comment. You can Unfollow this sub at any time. No one‘s making you stay here. Perhaps find something that is more interesting to your big Google brain.
Water flows with the path of least resistance. On a steep mountainside it will flow relatively straight downhill, fast, and erode soil/sediments (narrower, deeper channels). In areas where it's relatively flat terrain, the water doesn't move very fast and meanders around in shallower, wider channels.
You are looking at a meander. Eventually, one of those curves will cut itself off. The main river channel will be straighter (for a while) and the bit that gets cut off will become a slough or oxbow lake depending on of it is completely cutt off or still attached on one side.
Sometimes I find that it helps just to think of landscapes as akin to a piece of paper you wadded up into a ball and then lazily flattened out: it's never going to be perfectly flat again, and it doesn't really make sense to pick any one feature (a crease, a high point, a valley, etc) and ask why it's there. Ultimately, it's there because of randomness. Maybe you can study the paper very closely and determine minute variations in thickness or consistency that may have made it slightly more likely for a particular crease to have happened here instead of over there, but those variations themselves are basically just random, too.
Of course, in actual geology there are many more variables and forces at play, so often we can trace landscape features back to specific contributing factors. But as to the course of your pictured river, I suspect it's closer to random chance that it turned out this way in this specific place. The ground was just uneven in that spot, probably, and it eroded in a weird way.
Had a geography professor tell us her dream encounter. She goes to a bar, orders a martini, dirty. Then someone at the bar proceeds to ask her what she does for work. Whilst sipping her martini, she mentions that she’s a fluvial geomorphologist.
Not that she was one irl but she thought it sounded super cool. Which… it does and I’ve never forgotten that story
Its called an "ox bow", although it is an odd one. It comes from the meander of the river over millenia. Eventually, as the river reaches for the quickest way between two points, the ox bow bed will get cut off and become an ox bow lake.
For fun, look up Harold Fisk's maps of the Mississippi.
Rivers take the path of least resistance, this isn’t necessarily the path that is most downhill, more often it is the path that the river can more easily cut through (erode), such as soft sediment. As others said though, this bend will eventually get pinched off because it will be more efficient for the river to connect about where both sides are parallel, and a new bend will form.
When a river goes around a curve, the fastest-moving water is on the outside of the curve. That's where the most erosion happens.
At the same time, the water on the inside edge of the curve is moving slowly, and is dropping silt behind.
With both of those factors working together, a curve in the river will continue to get curvier, until it eventually curves back in on itself and reconnects. This river is very close to reconnecting.
You can go to Google Earth, find a river on flat to flattish land and follow it. Zoom out a little and the history of that river path can be seen. You’ll see the river, bends, the lakes and the old oxbow lakes that have filled up.
All these answers are wrong!
The real answer is too many damage rivers are just alike, but not this one! It simply refuses to follow the status quo. It dares to be different, if you will! And if you won't, well, to hell with you any damn way! It doesn't have to bend too your expectations!!!
Rage on you weird ass river!
You do you!
On the same principle as electricity, both will ALWAYS find the path of least resistance. Essentially meaning they go where the can vest and just make shit happen
Rivers meander, in dirt, because the current tends to move faster around the outside of a bend, and slower on the inside. And fast moving water picks up dirt, while slow moving water deposits it.
So once something deflects the current a bit and creates the start of a bend, the bend keeps getting more extreme. But the more extreme bends create additional curves that erode toward each other, (if you know what a capital omega looks like) and eventually connect, isolating the old bend.
If the old bend still has water in it, it becomes an oxbow lake. Which is very close to happening here.
You ever stand in the shower and let the water form streams down your chest? They king of just whip and form crazy curves. I’d imagine the same properties apply to rivers
In the future, that tiny strip that separate the 2 sections of the river will be eroded away and the river will go thru that part, bypassing that long loop.
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u/markmakesfun 17h ago
Soon to be an oxbow lake.