An experimental study of Mollisol aggregate loss characteristics during rainfall erosion processes Effects of raindrop kinetic energy on splash erosion in the typical black soil region of Northeast China PROGRESS OF NUCLIDE TRACING TECHNIQUE IN THE STUDY OF SOIL EROSION IN RECENT DECADE STUDY ON CHANGEABLE PROCESS OF SOIOL EROSION DISTRIBUTIVE CHARACTERISTICS ON THE SLOPE SURFACE BY REE TRACING METHOD Profile distribution of sediment particle sizes at a check dam in a small watershed of Loess Plateau