STABILITY OF THE POOL RIFFLE SEQUENCE IN CHANGING RIVER CHANNELS

The pool-riffle sequence as an important feature of river channels was described by Leopold et al. (1964) to occur with a spacing of five to seven times the channel width. Subsequent work has generally confirme d this spacing, although more closely spaced pools and riffles are quo ted for some channels in woodland basins and for some channelized stre ams. Although few detailed empirical studies have been made of adjustm ents of the pool-riffle spacing, a detailed survey of a 6 km channel r each containing over 300 riffles in the New Forest, southern England i ndicates that despite the influence of woody debris and channelization , the interriffle distance generally falls within the range of five to seven channel widths. As substantial adjustments in channel dimension s have been widely observed downstream of channelization schemes, land -use changes, and dams and reservoirs, the associated adjustments in p ool riffle spacing should be a consideration in channel management and an ingredient of design for channel restoration.