Disturbance, stream incision, and channel evolution: The roles of excess transport capacity and boundary materials in controlling channel response

Morphological Response of the Brahmaputra–Padma–Lower Meghna River System to the Assam Earthquake of 1950

“…They are most probably related to the fact that it is relatively easy for flow to re-entrain sediment that was only recently deposited in abandoned anabranches and so re-occupy them, compared to the more difficult task of increasing sinuosity through eroding banks formed in older, more consolidated floodplain sediments. Also, the high stream power (unit weight of water*discharge*slope) of these rivers restricts the tendency for incision and meandering unless the channel banks are highly resistant to erosion (Simon and Rinaldi 2006). If the banks are erodible, a reduction in sediment load is much more likely to trigger widening and a tendency to braid rather than incision and meandering.…”

“…However, in the rivers studied in this project the huge scale of their channel and floodplain systems diminishes the significance of slope adjustment in driving morphological response. Also, Simon and Rinaldi (2006) showed that river response through slope adjustment is insignificant in rivers like the Jamuna that can adjust their width and planform very easily due to their erodible, non-cohesive, sandy banks. Thus, the valley slope was not considered as an independent variable in the conceptual process-response model and neither was the channel slope considered as a dependent variable.…”

“…This assumption is revisited in the discussion presented here. There is a great deal of evidence from the literature that an imbalance between the sediment supply from upstream and the local sediment transport capacity will trigger marked changes in river morphology (Lane, 1955;Schumm, 1969;Galay, 1983;Chien, 1985;Zhou and Pan, 1994;Lagasse, 1994;Jiongxin, 1996;Kondolf et al 2002;Richard and Julien, 2003;Simon and Rinaldi, 2006) and this is the basis for the conceptual model developed in this thesis. However, in the model, no consideration was given to the amount of energy available to transport sediment and how this change in comparison to the energy required to transport the sediment supplied, as the channel adjusts.…”

Convergence of agricultural intensification and climate change in the Midwestern United States: implications for soil and water conservation

“…This is partly because increases in discharge can increase bank erosion, but also clearly results from historical sediment accumulation, which originated from croplands that were eroded at very large rates in the decades before the soil conservation movement in the USA (before 1940). While the story of changes in Midwestern rivers is somewhat complicated (Simon and Rinaldi 2006), the management of rivers and riparian corridors is germane to management of sediment and water quality in the Midwest. The fact that key ongoing challenges to river corridor management result from agricultural erosion that occurred long ago illustrates the importance of linking management of river corridors and agricultural practices.…”

Prediction of channel degradation rates in urbanizing watersheds

“…This results in channel degradation (Booth, 1990;Allen et al, 2002). Schumm et al (1984), Simon (1989), Rosgen (1996) and Simon & Rinaldi (2006) have shown that such degradation leads to a fairly predictable sequence of channel evolution. In more rural areas, such degradation can be handled by reconnecting the channel to the flood plain through meander restoration.…”