Bed-load transport refers to the movement of particles (such as sand, gravel, pebbles) along the bed of a river or stream by rolling, sliding, or saltation (bouncing). This process is important for the geomorphic evolution of rivers and streams, as it can shape the channel morphology and influence sediment transport processes. Researchers in this area study the dynamics of bed-load transport, including the factors that influence the rate and direction of particle movement, as well as the impact of bed-load transport on river ecosystems and habitats. They often use field observations, laboratory experiments, and numerical models to better understand and predict bed-load transport behavior.