Spatial Patterns of Geomorphic Processes in Channelized Tributary Streams

Abstract

Channelization of rivers can alter channel morphology and sediment dynamics for decades and as a result, channelization is considered to be one of the most profound forms of human-induced disturbance in fluvial systems. Previous research conducted in large alluvial rivers suggests that spatial patterns of geomorphic adjustment processes vary with distance from the channelized reach. Few studies have investigated spatial patterns of geomorphic processes in smaller, tributary streams, which differ to larger systems in a variety of ways. I examined spatial patterns of widening and incision in three tributary streams with similar land use history and geology, using w/d ratios calculated from field measurements of channel morphology. Spatial patterns of w/d ratios suggest that channel incision dominates two of the tributaries, while widening dominates a third tributary. These results suggest that because tributary streams are smaller in area than larger rivers, one type of geomorphic adjustment process can dominate the entire watershed. The dominance of channel widening or incision throughout a system results in large amounts of sediment being produced throughout the system at one time.

Keywords:

• geomorphic adjustment
• channelization
• tributaries