Downstream Variability of Fluvial Form, Process, and Character in a Small Deglaciated Watershed, Southern Ontario

• Main Author: Thayer, James Benjamin
• Other Authors: Desloges, Joseph R.
• Language: en_ca
• Published: 2012
• Subjects: Channel morphology; Downstream adjustment; Glacial control; Floodplain sedimentology; 0368; 0388
• Online Access: http://hdl.handle.net/1807/33568

Many deglaciated watersheds possess complex longitudinal profiles and spatially variable sediment sources derived from the last glaciation. Accordingly, downstream patterns in fluvial forms and characteristics of the channel and floodplain may diverge from conventional ‘graded’ watershed models where channel slope decreases downstream. Within a small, deglaciated watershed, five distinct fluvial forms were identified and it was found that the watershed is organized in a spatially variable, but generally inverted arrangement with stable, low-energy forms dominating the upper watershed and more dynamic, high-energy forms in the lower watershed. As a consequence of this inverted and variable downstream succession, and the spatially erratic organization of glacial sediment sources, downstream trends in channel and floodplain characteristics are poorly defined, and in many cases, deviate from expected trends. This is most true for sedimentological variables where multiple co-dominant controls exist, while morphological and hydrological variables better conform to expected downstream trends.