GGR201H1 Lecture Notes - Lecture 4: Knickpoint, Suspended Load, Wash Load
11 Jan 2017
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Document Summary
Variables which control river channel morphology tend to vary gradually (sediment size, baseflow inputs, valley slope, vegetation) Others can vary more abruptly: geology, tributary discharge inputs, knickpoints in slope. Reach = length of river which has relatively uniform characteristics. Inter-reach variability is greater than the intra-reach variability. Strea(cid:373) power (cid:894) (cid:895) is a produ(cid:272)t of power (cid:271)ased tra(cid:374)sfer of (cid:373)o(cid:373)e(cid:374)tu(cid:373) fro(cid:373) fluid to boundary (mediated by boundary entrainment threshold) Meandering channel: single, sinuous thread, active meandering (lateral migration). Associated with low gradient, cohesive banks, dominated by wash load, but can include significant bed load and suspended load transport: cut bank and point bar pairings. Braiding channel: network of multiple channels flowing around dynamic (unstable) bar forms. Wandering: transition between braided and meandering (single dominant channel with braid bars which can be stable and colonized by vegetation and back channels). Anabranching: have multiple channels which bifurcate around semi-stable islands: low gradient, cohesive (or well vegetated banks)
