A modern accelerated erosion phase, post-dating the beginning of European-style farming in New Zealand, is associated with a depletion in the vegetation cover of Centre Creek catchment (Broken River area, South Island), and has caused substantial modification of streambed forms. An increase in the supply of debris to stream beds resulting from concentrated gullying, mass movement processes, and snow avalanche activity has caused (a) changes in the shape of the longitudinal profiles, (bl the formation of alluvial, valley bottom terraces, and (c) general widening and aggradation of the stream bed in the lower reaches. Some of the streambed processes operating in Centre Creek are briefly described.