Rivers meander in their lower course because they are following the path of least resistance. As rivers flow, they erode and deposit sediment along their banks, causing them to curve, turn, and loop. This process is known as "meandering." Meandering curves slow down the flow of water and distribute sediment more evenly along the river's banks, leading to a wider, more stable river channel. As the river reaches its lower course and the gradient flattens, the meandering curves become more pronounced.