Upscaling Sediment‐Flux‐Dependent Fluvial Bedrock Incision to Long Timescales

Abstract

• Analytical solution from explicit upscaling of a sediment-flux-dependent fluvial bedrock incision model to long time scales. • The model includes solutions similar to those obtained in the stream power paradigm, in addition to other possible solutions. • The model explicitly resolves forcing behavior and highlights potential dynamic feedbacks that have so far not been considered.

From Process to Centuries: Upscaling Field‐Calibrated Models of Fluvial Bedrock Erosion

“…Such events could cause orders of magnitude higher erosion rates than typical annual floods, as long as the bedrock bed remains exposed. Upscaling bedload tool-and cover-dependent predictions (SAws or RSA model) is appropriate to assess river erosivity exceeding centennial scales (Turowski, 2021). In addition, these models can be inverted to estimate long-term bedload supply from measured incision rates.…”

“…Upscaling bedload tools-and cover-dependent predictions (SAws or RSA model) is appropriate to assess river erosivity exceeding centennial scales [Turowski , 2021]. In addition, these models can be inverted to estimate long-term bedload supply from measured incision rates.…”

The influence of bedrock river morphology and alluvial cover on gravel entrainment. Part 2: Modelling critical shear stress

“…How τ c changes with increasing cover has implications for predicting the relationship between sediment flux and sediment cover, which is important for modelling channel incision and landscape evolution (Lague, 2010;Sklar & Dietrich, 2004;Turowski, 2021). If sediment cover increases τ c , in turn making sediment grains less mobile, then this positive feedback can produce rapid deposition of sediment cover, known as runaway alluviation (Chatanantavet & Parker, 2008;Demeter et al, 2005;Finnegan et al, 2007).…”

Impact of Changing Concavity Indices on Channel Steepness and Divide Migration Metrics

“…For example, Wickert and Schildgen (2019) predict that in gravel bed rivers, subsidence and uplift modulate the concavity index, with lower values of θ when sediment flux is low or tectonic uplift is high. A recent model proposed by Turowski (2021) suggests that when the bedload fraction is independent of drainage area, concavity index values can range widely, with values ranging from 0.25 to 0.625 for -3-…”

“…For example, Wickert and Schildgen (2019) predict that in gravel bed rivers, subsidence and uplift modulate the concavity index, with lower values of E  when sediment flux is low or tectonic uplift is high. A recent model proposed by Turowski (2021) suggests that when the bedload fraction is independent of drainage area, concavity index values can range widely, with values ranging from 0.25 to 0.625 for choices of bedload transport equations and channel width scaling that have been observed in nature. We would argue that there is no consensus as to the correct model, and even if you believed one of the above models were correct, unless direct observations of incision process, sediment flux, uplift and other factors were available it would be a challenge to calculate the concavity index based on parameterizing a model.…”