There are so many beautiful rivers in the world, but have you ever wondered, why they never run straight? That’s because the earth rotates all the time, but water cannot transfer instantaneously. The rivers become curved under the force of gravity, but this does not affect the direction of rivers. Therefore, none of the rivers on the earth flow in a straight line.

The geostrophic deflection force deflects a horizontally moving object to the right of its forward direction in the northern hemisphere and to the left in the southern hemisphere. Taking rivers in the northern hemisphere as an example, under the influence of geostrophic deflection force, the river always tends to deviate to the right, so the right bank of the river is always scoured, while there is often sand and gravel accumulation on the left bank because there are not so many rivers rushing towards it and the flow velocity is slow. Over time, even the originally straight river will begin to bend.

There are also complex terrains that make it absolutely impossible for rivers to flow forward in a straight line, which is one of the most common reasons, but even in wide plain areas, rivers are always winding, because the chemical composition and quantity of salt and alkali contained in the soil on both sides of the river cannot be completely dissolved in water. It has changed the ability of the soils on both sides to withstand the impact of water flow to varying degrees.