Studying how water flows and moves sediment in steep mountain streams is crucial for predicting floods and understanding how landscapes change. In a river flume experiment, researchers found that flow resistance and sediment transport rates are different on steep riverbeds compared to flat ones. They discovered that the roughness of the riverbed and the type of bedforms present affect how water flows and carries sediment. Some unusual bedforms, like stepped alternate bars, were observed in the experiment. The researchers also found that existing models for sediment transport in low-gradient rivers don't work as well for steep streams. Overall, the study provides valuable insights into how water and sediment interact in fast-flowing mountain rivers.