Catchment‐ and reach‐scale controls on the distribution and expectation of geomorphic channel adjustment

Abstract

Abstract Variability in channel function (behavior) can be assessed by characterizing different forms of adjustment over time. Here, historical channel adjustments in three tributary systems of the Lockyer Valley, Southeast Queensland (SEQ) are analyzed in order to evaluate the range of catchment‐ and reach‐scale controls on channel behavior. Over 300 individual adjustments and 13 forms of adjustment were identified over a ∼130 year time span. We measured the width‐to‐depth ratio ( W:D ), mean stream power ( ω ), and basin area ( A ) at the location of all observed adjustments. The most common forms of adjustment were avulsions, lateral expansion of the channel, and bend adjustments. The tributary systems behave distinctly different from one another according to statistical comparisons between the W:D , ω , and A data for these forms of adjustment. We find that it is possible to develop process domains or typologies for forms of geomorphic adjustment found in the Lockyer Valley. These domains or typologies provide the foundations for synoptic comparisons between catchments and assessing the expectation of channel adjustment (forecasting), which should be included in process‐based river management practice.