There's a link to a video that explains it. tl;dw: when rivers are very sinuous, the kinks turn into oxbow lakes and separate from the river, so that limits ho

There's a link to a video that explains it. tl;dw: when rivers are very sinuous, the kinks turn into oxbow lakes and separate from the river, so that limits how sinuous they can get. On the other hand, rivers' bends are constantly amplified by erosion. Researchers modeling these phenomena showed that under certain assumptions, these forces are in equilibrium at a sinuosity of ᴨ.