Few rivers in the world are straight, but most rivers are curved. Why?

The reason why the river bends is mainly because the velocity on both sides of the river is different, one side is fast and the other is slow. On the faster side of the river, the impact on the bank is also greater, and the soil is more likely to collapse. When the river bank collapses, it will bend the river. When the river bends, it will present an S-shaped bank (both banks are like a concave and a convex), and it will continue to develop. The water will rush to the concave bank, while the water flow on the convex bank is slow, and the gravel and soil brought by the river will slowly deposit. Over the years, the concave bank will become more and more concave, the convex bank will become more and more convex, and the river will show a winding appearance.

In addition, the complicated terrain makes it absolutely impossible for rivers to flow straight ahead, which is one of the most common reasons. But even on the vast plain, the river always twists and turns. Because the chemical components such as salt and alkali contained in the soil on both sides of the river and their quantities cannot be completely contained in the water, the ability of the soil on both sides of the river to withstand the impact of water flow has been changed to varying degrees. Because the direction of the earth's rotation is from west to east, it will also change the straight direction of rivers, making the rivers in the northern hemisphere scour the right bank more seriously than the left bank, while the rivers in the southern hemisphere are just the opposite.

Because water flows along a curve, when water deviates slightly in a certain place, it will be pressed to the concave shore under the action of centrifugal force; At the same time, the riverbed should be separated from the protruding shore. In this way, the river not only has no chance to restore the straight direction, but also makes the deviation bigger and bigger, turning into a curved curve, and the curve rate is getting bigger and bigger. Because the centrifugal force is also increasing, at the same time, the river can't flow along the river bed, but always turns from one side to the other, that is, from the concave edge to the nearest convex edge. Therefore, the river presents a winding flow direction.

In this way, after thousands of years of scouring, numerous repetitions and cycles, and due to the slow flow speed on the protruding embankment, more and more sediment was deposited, forming a winding river.