Regulated flushing in a gravel-bed river for channel habitat maintenance: A Trinity River fisheries case study

Nelson, R. Wayne; Dwyer, John R.; Greenberg, Wendy E.

doi:10.1007/bf01867656

Cited by 20 publications

(20 citation statements)

References 4 publications

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“…Collier, 2002;Nelson and Dwyer, 1987;Peviani et al, 1996). Most contributions deal with flushing operations, which are meant to reduce reservoir sedimentation and focus on the release of fine material (e.g.…”

Section: Introductionmentioning

confidence: 91%

Effects of dam operation on downstream river morphology: the case of the middle Zambezi River

Khan

Mwelwa-Mutekenya

Crosato

et al. 2014

Proceedings of the Institution of Civil Engineers - Water Manag

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The sand-bed middle Zambezi River flows between two large dams: the Kariba in Zambia and Zimbabwe upstream and the Cahora Bassa in Mozambique downstream. Since the construction of Kariba for hydropower production in 1959, the river discharge has been regulated according to two different strategies. This makes the middle Zambezi a unique case for studying the effects of different dam operations on the long-term morphological trends of the river.To analyse these effects, this work focused on the interaction between the river morphological changes and the groundwater flow. The comprehensive approach, combining numerical modelling, analysis of field and historical data, as well as theoretical considerations, led to the conclusion that the morphological response of the middle Zambezi to damming has been mainly affected by the sudden closure of the dam flood-gates, originating seepage forces causing bank instability and river widening as a result. The local climatic oscillation, comprising dry and wet periods having a duration of tens of years, was found to have played a major role in the flow regulation, which resulted in a constant discharge in the period between 1982 and 2000. Notation Baverage river width (m) b exponent of the sediment transport formula C Chézy coefficient for roughness (m 1/2 s À1 ) h average water depth (m) i longitudinal slope of the water surface and channel bed (m/m) m parameter in the sediment transport formula (m 2-b s b-1 ) nManning coefficient for roughness (s/m 1/3 ) Q s total volume of transported sediments (including pores) (m 3 /s) Q w water discharge (m 3 /s) u flow velocity (m/s) í H horizontal eddy viscosity (m 2 /s) D H horizontal eddy diffusivity (m 2 /s)

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Section: Introductionmentioning

confidence: 91%

Effects of dam operation on downstream river morphology: the case of the middle Zambezi River

Khan

Mwelwa-Mutekenya

Crosato

et al. 2014

Proceedings of the Institution of Civil Engineers - Water Manag

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“…At present, mandated annual flow releases are being implemented in conjunction with gravel augmentation and mechanical channel alterations in an attempt to improve the fluvial habitat. In particular, an annual flood hydrograph is released from the dams to reproduce some features of the unregulated flow that are necessary for the maintenance of complex bend and bed topography (i.e., armor turnover, periodic scour and fill, and bar migration) because these features promote the development and maintenance of a healthy habitat for the salmonid population [e.g., Wilcock et al , 1996; Nelson et al , 1987].…”

Section: Introductionmentioning

confidence: 99%

A model to predict the evolution of a gravel bed river under an imposed cyclic hydrograph and its application to the Trinity River

Viparelli

Gaeuman²,

Wilcock

et al. 2011

Water Resources Research

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[1] Major changes in the morphology of the Trinity River in California, such as narrowing of the cross section and sedimentation of fine sediment in pools, occurred after the closure of a system of dams. These changes caused a dramatic reduction in the salmonid population and a resulting decline of the fishery. Gravel augmentation, regulated flood releases, and mechanical channel rehabilitation are currently being implemented to help restore the aquatic habitat of the river. The present paper describes a tool, named the Spawning Gravel Refresher, for designing and predicting the effects of gravel augmentation in gravel bed rivers. The tool assumes an imposed, cycled hydrograph. The model is calibrated and applied to the regulated reach of the Trinity River in four steps: (1) zeroing runs to reproduce conditions of mobile bed equilibrium as best can be estimated for the predam Trinity River, (2) runs to compare the predictions with the results of previous studies, (3) runs at an engineering time scale to reproduce the effects of the dams, and (4) runs to design gravel augmentation schemes. In the fourth group of runs, the combined effects of engineered flood flow releases and gravel augmentation are predicted. At an engineering time scale, the model indicates that the fraction of fine sediment in the surface layer and in the topmost part of the substrate should decrease when subjected to these two restoration measures, with a consequent improvement of the quality of the spawning gravel.Citation: Viparelli, E., D. Gaeuman, P. Wilcock, and G. Parker (2011), A model to predict the evolution of a gravel bed river under an imposed cyclic hydrograph and its application to the Trinity River, Water Resour.

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“…Post-logging monitoring at Carnation Creek revealed a significant increase in fine sediment (4.6%), mostly caused by an increase in the sand component as a results of inputs associated with soil disturbance, bank erosion and flood events such as a storm (with a return period of 25 years), which occurred four years after the end of the logging phase (Scrivener and Tripp, 1998). In contrast, Nelson et al (1987) have found that in the Trinity River, which was heavily impacted by a drainage basin with severe erosion, the percentage of accumulated fine sediment (<2 mm) was greater than 70% in some reaches. Caissie and Arseneau (1999) have compared the substrate composition of Catamaran Brook with two other Atlantic Canada rivers, namely the Point Wolfe River (New Brunswick) and the Morell River (Prince Edward Island).…”

Section: Discussionmentioning

confidence: 76%

“…In contrast, anthropogenic activities such as agriculture and timber harvesting practices can change the flow regime and sediment loading at relatively lower discharge. Such sediment loading can affect the spawning, nursery and winter habitat of salmonids (Brown and Krygier, 1971;Nelson et al, 1987;Waters, 1995;Cunjak et al, 1999). Both natural and man-made perturbations occur at various temporal and spatial scales.…”

Section: Introductionmentioning

confidence: 99%

Streambed sediment composition and deposition in a forested stream: spatial and temporal analysis

et al. 2005

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Assessment of fish habitat quality often includes the measurement of substrate composition and fine sediment deposition in streams. The natural spatial (localized, inter-reach) and temporal (event-specific, seasonal, annual) variability of both sediment deposition and streambed composition were investigated in Catamaran Brook (New Brunswick, Canada). A grab-type sampler (i.e. scoop) and Whitlock-Vibert boxes were used to investigate grain size distribution of streambed material and deposition of fine sediments over time.Results showed that the scoop sampler was a good method to quantify intra-site and inter-site grain-size distribution, especially as it relates to the streambed composition and changes thereof. In Catamaran Brook, scoop samples showed that gravel constituted the highest percentage of the total dry weight with a median of 38.8%, for seven sites monitored in three different study reaches. The median percentage of fines (i.e. material <2 mm) was found to be 10.8% of total weight. Intra-site variation in substrate grain size distribution was also assessed using the scoop sampler. Significant differences in the distribution of fine sediments within a study reach as well as among habitat types (riffles, runs, etc.) were found, which reiterates the importance of taking multiple samples. To observe changes in fine sediment, a subsample of the scoop sampler limited to grain sizes <32 mm was used to reduce some of the variability in weight percentages due to large substrate material, e.g. cobbles. The percentage of fines within this subsample varied between 15.2% and 20.0% (overall median of 18.6%). Statistical analyses showed that the temporal variability in grain size distribution was significant and was mainly associated with hydrological events such as midwinter thaw and summer peak flows. Fredle indices (f i ), an index for assessing survival of incubating alevins, were calculated in Catamaran Brook and varied between 2.9 and 13.1, with marked spatial and temporal variability. There was a general decrease in f i in the autumn of 1996, which may have been related to a redistribution of fines within the drainage basin. Whitlock-Vibert boxes appeared to be more efficient for determining storage rates than for substrate composition analyses. The median storage rate in Catamaran Brook was 40 kg/m 2 /year. Fine sand median storage rate was 9.4 kg/m 2 /year. Our study indicates that scoop samplers and Whitlock-Vibert boxes should both be used, in order to assess sediment deposition and variation in grain size distribution simultaneously.

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Regulated flushing in a gravel-bed river for channel habitat maintenance: A Trinity River fisheries case study

Cited by 20 publications

References 4 publications

Effects of dam operation on downstream river morphology: the case of the middle Zambezi River

Effects of dam operation on downstream river morphology: the case of the middle Zambezi River

A model to predict the evolution of a gravel bed river under an imposed cyclic hydrograph and its application to the Trinity River

Streambed sediment composition and deposition in a forested stream: spatial and temporal analysis

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