15Caesium-137 derived from nuclear testing in the past century has been widely used as a 16 sediment tracer of soil redistribution, providing information on medium term (40-50 17 years) erosion rates. To date, most studies have focused on individual fields of limited 18 extent, but estimated rates and patterns of soil redistribution require upscaling to 19 catchment level. An attempt to assess soil redistribution processes with strong 20 geomorphic control on complex terrain, such as an internally drained karstic catchment, 21 is presented in this work. A comprehensive geomorphological survey of the Estanya 22 Lake catchment (Spanish Pyrenees) enabled the main geomorphic elements to be 23 identified with a grid resolution of 5 x 5 m, which was the basis for the terrain analyses.