Gravel-bed rivers have a pulsating nature in how sediment moves, even with steady water flow. Researchers studied how sediment waves move in gravel-bed channels with alternate bars. They found that these waves migrating from pool to pool are the main way sediment moves. Sometimes, these waves cause bar failures, leading to big pulses of sediment. Over long periods, the bedload transport rates fluctuate in a quasi-periodic way, showing that the amount of sediment the riverbed can hold affects how much sediment moves.