The influence of contemporary flow regime on the geomorphology of the Sabie River, South Africa

Broadhurst, L. J.; Birkhead, A. L.

doi:10.1016/s0169-555x(00)00090-8

Cited by 25 publications

(13 citation statements)

References 25 publications

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“…The morphology of the macrochannel (cf. Heritage et al ., 2001) is controlled by short‐duration, high‐discharge events (Fielding & Alexander, 1996).…”

Section: The Burdekin Riversupporting

confidence: 81%

Supply limited sediment transport in a high‐discharge event of the tropical Burdekin River, North Queensland, Australia

Amos¹,

Alexander²,

Horn³

et al. 2004

Sedimentology

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Interactions between catchment variables and sediment transport processes in rivers are complex, and sediment transport behaviour during high‐flow events is not well documented. This paper presents an investigation into sediment transport processes in a short‐duration, high‐discharge event in the Burdekin River, a large sand‐ and gravel‐bed river in the monsoon‐ and cyclone‐influenced, semi‐arid tropics of north Queensland. The Burdekin's discharge is highly variable and strongly seasonal, with a recorded maximum of 40 400 m3 s−1. Sediment was sampled systematically across an 800 m wide, 12 m deep and straight reach using Helley‐Smith bedload and US P‐61 suspended sediment samplers over 16 days of a 29‐day discharge event in February and March 2000 (peak 11 155 m3 s−1). About 3·7 × 106 tonnes of suspended sediment and 3 × 105 tonnes of bedload are estimated to have been transported past the sample site during the flow event. The sediment load was predominantly supply limited. Wash load included clay, silt and very fine sand. The concentration of suspended bed material (including very coarse sand) varied with bedload transport rate, discharge and height above the bed. Bedload transport rate and changes in channel shape were greatest several days after peak discharge. Comparison between these data and sparse published data from other events on this river shows that the control on sediment load varies between supply limited and hydraulically limited transport, and that antecedent weather is an important control on suspended sediment concentration. Neither the empirical relationships widely used to estimate suspended sediment concentrations and bedload (e.g. Ackers & White, 1973) nor observations of sediment transport characteristics in ephemeral streams (e.g. Reid & Frostick, 1987) are directly applicable to this river.

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“…The morphology of the macrochannel (cf. Heritage et al ., 2001) is controlled by short‐duration, high‐discharge events (Fielding & Alexander, 1996).…”

Section: The Burdekin Riversupporting

confidence: 81%

Supply limited sediment transport in a high‐discharge event of the tropical Burdekin River, North Queensland, Australia

Amos¹,

Alexander²,

Horn³

et al. 2004

Sedimentology

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“…In Tooth's (2000) description of dry-land rivers, large-magnitude floods are the major landscape driver, as low flows lack capacity to do extensive geomorphic work in intervening periods. Contrastingly, Heritage et al (2001) found that the channel form of the Sabie River, South Africa, is not related to a single channel-forming discharge, but rather to low frequency, large flood events, as well as high frequency, comparatively low-flow events. In some cases, a combination of hydroclimatic trends and the occurrence of channel stabilising riparian vegetation may be important in determining channel shape (Dollar and Rowntree, 1995;Rowntree and Dollar, 1996;1999).…”

Section: Introduction and Regional Setting Streamflow Variabilitymentioning

confidence: 67%

Hydrology, sediment transport dynamics and geomorphology of a variable flow river: The Mfolozi River, South Africa

Grenfell¹,

Ellery²

2012

WSA

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The co-efficient of variation for inter-annual streamflow of the Mfolozi River is extremely high at 79%. An analysis of flow frequency indicated that streamflow is skewed towards low-flow values, with a number of extremely large flood events occurring as outliers on the histogram. Streamflow variability in the Mfolozi River may be linked to multiple factors including a large catchment size, a seasonal climate of a dry winter and wet summer, evergreen vegetation in the catchment, variable precipitation and the occurrence of regionally pervasive climatic oscillations. This research aimed to address how streamflow variability impacted upon sediment transport and thus, geomorphology. It was found that sediment transport variability occurred at the intra-and inter-annual scale. Analysis of mean monthly sediment concentration and discharge showed a hysteresis effect, such that sediment concentration peaked prior to discharge in the early wet season. During the late wet season, peak discharges often had unexpectedly low sediment concentrations. Furthermore, data suggested the existence of long-term hysteresis that may be related to decadal-scale climatic oscillations that alter sediment availability and stream capacity, resulting in discharge peaking in 2000 and sediment concentration in 2005. However, more data are required to confirm this relationship. Variability in streamflow appears to share a causal relationship with sediment transport variability, as both are linked to variation in precipitation and the resultant impacts on vegetation growth and evapotranspiration rates. The variability of streamflow and sediment transport has implications for stream and floodplain geomorphology, and the hydrology of variable rivers should be considered when interpreting their geomorphology.

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“…Following the idea of Heritage et al (2001), we paid particular attention to morphological features that could be traced throughout the river reaches ( Figure 2). The axis (AX) feature corresponds to the lowest point in the cross-section.…”

Section: Field Surveysmentioning

confidence: 99%

Determination of bankfull discharge magnitude and frequency: comparison of methods on 16 gravel‐bed river reaches

Navrátil¹,

Albert²,

Herouin³

et al. 2006

Earth Surf Processes Landf

101

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International audienceBankfull discharge is identified as an important parameter for studying river morphology, sediment motion, flood dynamics and their ecological impacts. In practice, the determination of this discharge and its hydrological characteristics is not easy, and a choice has to be made between several existing methods. To evaluate the impact of the choice of methods, five bankfull elevation definitions and four hydrological characterizations (determination of duration and frequency of exceedance applied to instantaneous or mean daily data) were compared on 16 gravel-bed river reaches located in France (the catchment sizes vary from 10 km2 to 1700 km2). The consistency of bankfull discharge estimated at reach scale and the hydraulic significance of the five elevation definitions were examined. The morphological definitions (Bank Inflection, Top of Bank) were found more relevant than the definitions based on a geometric criterion. The duration of exceedance was preferred to recurrence intervals (partial duration series approach) because it is not limited by the independency of flood events, especially for low discharges like those associated with the Bank Inflection definition. On average, the impacts of the choice of methods were very important for the bankfull discharge magnitude (factor of 1·6 between Bank Inflection and Top of Bank) and duration of exceedance or frequency (respectively a factor 1·8 and 1·9 between mean daily and instantaneous discharge data). The choice of one combination of methods rather than another can significantly modify the conclusions of a comparative analysis in terms of bankfull discharge magnitude and its hydrological characteristics, so that one must be cautious when comparing results from different studies that use different methods

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The influence of contemporary flow regime on the geomorphology of the Sabie River, South Africa

Cited by 25 publications

References 25 publications

Supply limited sediment transport in a high‐discharge event of the tropical Burdekin River, North Queensland, Australia

Supply limited sediment transport in a high‐discharge event of the tropical Burdekin River, North Queensland, Australia

Hydrology, sediment transport dynamics and geomorphology of a variable flow river: The Mfolozi River, South Africa

Determination of bankfull discharge magnitude and frequency: comparison of methods on 16 gravel‐bed river reaches

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