PROJECT DETAILS ONLY - NO DATA. The long term mobility of different sized pebbles under different hydraulic conditions will be investigated by re-mapping 1220 magnetically tagged pebbles which have been dispersing since 1991 from 6 points in a Scottish river. Travel distances and burial depths of recovered tracers will be analysed in relation to pebble size, local bed grain size, and local mean shear stress. The travel distance results will show whether shorter term relationships (including one from a 1991-3 study of these tracers) apply over the longer term or are distorted by deep burial and bar storage. The data will also give insight into long term mixing depths (about which assumptions must be made in numerical models), shape sorting, and abrasion rates.