Handbuch des Wasserbaues

Schoklitsch, Armin

doi:10.1007/978-3-642-52043-3

Cited by 65 publications

(62 citation statements)

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“…Based on Schoklitsch (1962), Bathurst and colleagues (Bathurst et al, 1983Bathurst, 1987) derive an alternative approach using discharge per unit flow width, or critical unit discharge (q c ). Bathurst's original equations are reworked by Ferguson (1994) and the modified formulation is used here: …”

Section: Flow Competence and Bed Materials Mobilitymentioning

confidence: 99%

Flood magnitude–frequency and lithologic control on bedrock river incision in post-orogenic terrain

Jansen

2006

Geomorphology

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Mixed bedrock-alluvial rivers-bedrock channels lined with a discontinuous alluvial cover-are key agents in the shaping of mountain belt topography by bedrock fluvial incision. Whereas much research focuses upon the erosional dynamics of such rivers in the context of rapidly uplifting orogenic landscapes, the present study investigates river incision processes in a post-orogenic (cratonic) landscape undergoing extremely low rates of incision (< 5 m/Ma). River incision processes are examined as a function of substrate lithology and the magnitude and frequency of formative flows along Sandy Creek gorge, a mixed bedrock-alluvial stream in arid SE-central Australia. Incision is focused along a bedrock channel with a partial alluvial cover arranged into riffle-pool macrobedforms that reflect interactions between rock structure and large-flood hydraulics. Variations in channel width and gradient determine longitudinal trends in mean shear stress (τ b ) and therefore also patterns of sediment transport and deposition. A steep and narrow, non-propagating knickzone (with 5% alluvial cover) coincides with a resistant quartzite unit that subdivides the gorge into three reaches according to different rock erodibility and channel morphology. The three reaches also separate distinct erosional styles: bedrock plucking (i.e. detachment-limited erosion) prevails along the knickzone, whereas along the upper and lower gorge rock incision is dependent upon large formative floods exceeding critical erosion thresholds (τ c ) for coarse boulder deposits that line 70% of the channel thalweg (i.e. transport-limited erosion).The mobility of coarse bed materials (up to 2 m diameter) during late Holocene palaeofloods of known magnitude and age is evaluated using step-backwater flow modelling in conjunction with two selective entrainment equations. A new approach for quantifying the formative flood magnitude in mixed bedrock-alluvial rivers is described here based on the mobility of a key coarse fraction of the bed materials; in this case the d 84 size fraction. A 350 m 3 /s formative flood fully mobilises the coarse alluvial cover with τ b ∼200-300 N/m 2 across the upper and lower gorge riffles, peaking over 500 N/m 2 in the knickzone. Such floods have an annual exceedance probability much less than 10 − 2 and possibly as low as 10 − 3 . The role of coarse alluvial cover in the gorge is discussed at two scales: (1) modulation of bedrock exposure at the reach-scale, coupled with adjustment to channel width and gradient, accommodates uniform incision across rocks of different erodibility in steady-state fashion; and (2) at the sub-reach scale where coarse boulder deposits (corresponding to τ b minima) cap topographic convexities in the rock floor, thereby restricting bedrock incision to rare large floods. While recent studies postulate that decreasing uplift rates during post-orogenic topographic decay might drive a shift to transport-limited conditions in river networks, observations here and elsewhere in post-orogenic settings sugge...

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Section: Flow Competence and Bed Materials Mobilitymentioning

confidence: 99%

Flood magnitude–frequency and lithologic control on bedrock river incision in post-orogenic terrain

Jansen

2006

Geomorphology

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“…Schoklitsch (1930) stated that the average bed shear stress in DuBoys equation is a poor criterion when applied to field computations, because the shear distribution in the channel cross-section is quite non-uniform. Einstein (1942) developed a relationship for sediment transport based on the probability theory.…”

Section: Bed Load Sediment Transportmentioning

confidence: 99%

Role of Sediment Transport in Operation and Maintenance of Supply and Demand Based Irrigation Canals: Application to Machai Maira Branch Canals

Munir¹

2011

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“…Analytical studies of open-channel bed degradation include those by Lane (1948), Mostafa (1957), Tinney (1962), Breusers (1967), Komura and Simons (1967), Aksoy (1970Aksoy ( , 1971, Hales and others (1970), Komura (1971), Rzhanitzin andothers (1971), de Vries (1973), Hwang (1975), andStrand (1977). Special flume studies of bed degradation have been conducted by Schoklitsch (1950), Harrison (1950), Newton (1951), Ahmad (1953), Willis (1965), Garde and Hasan (1967), Ashida and Michiue (1971), and others.…”

Section: In Bed Elevationmentioning

confidence: 99%