Sediment erosion and transport are essential processes for structuring physical habitats in fluvial systems, but developing techniques to predict how and when sediment moves, and where that material will end up has proved difficult. That poses problems for engineers and communities trying to protect bridges, dams, levees and pumps from shifting sediment, and for ecologists trying to plan river successful restoration projects or understand patterns in biodiversity. We have developed two new techniques for better understanding processes that regulate the erosion, transport and deposition of fine sediments (<2mm) and cobbles (>128mm) in rivers. A digital elevation model, radiometric map and multiple geochemical tracers including physical characteristics, major and trace elements, and stable isotopes combined in a mixing model were successfully used to identify the sources of fine sediments dominating a large sediment slug in the lowland reaches of the Pages River. For large sediment, we have developed and validated ‘Smart Rocks’, artificial cobbles fitted with a GPS, triaxial accelerometer and radiotracker that allow the mapping of the conditions triggering cobble transport, as well as the specific path travelled by individual rocks during high flow events. When combined, these methods represent a significant advancement in fine- and large-scale sediment modelling in river systems, and substantially improve our current conceptual basis of sediment dynamics in rivers.