The relation of the length of typical drift pieces to the channel width is critical in determining the rate of transport and the type and amount of stored drift in the channel. The depth and slope of the channel also affect its ability to move drift. Large woody debris in stream channels typically decays slowly.
Most drift is transported within the channel rather than in the flood plain.
The size of drift is critical in determining whether it can be transported. Logs longer than the width of the channel typically become lodged across the channel, and rarely move without being broken into smaller pieces. In small channels with large amounts of stable woody debris, pieces with a length more than half the channel width are relatively stable. Exceptions to this pattern include steep streams subject to debris torrents, and valleys where drift is transported outside the channel over a cleared, deeply inundated flood plain. 139K GIF version of this photograph Figure 12 .