water moves faster along the outer bends, giving it an increased capacity for carrying sediments. this results in erosion happening faster near the outer curves. on the other hand, water is slower near the inner bends, forcing the sediments carried by the river to deposit there. this interaction makes the rivers more bendy. an interesting result of this phenomenon is the formation of oxbow lakes (those c-shaped bodies of water separated from the main river)
Shattered Pixel Dungeon and/or Hoplite. Or maybe an ebook reader.