Hydraulic Properties of the Riffle Crest and Applications for Stream Ecosystem Management

Rossi, Gabriel J.; Mierau, Darren W.; Carah, Jennifer

doi:10.1111/1752-1688.12961

Cited by 6 publications

(11 citation statements)

References 57 publications

(110 reference statements)

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“…The riffle–pool unit is a dominant geomorphic feature in most alluvial streams. During low flow, they can be partially or completely isolated from each other, and so can provide discrete habitats for evaluating juvenile salmonid rearing and foraging (Naman et al, 2018; Rossi, Mierau, & Carah, 2021). We selected riffle–pool units that supported multiple age classes of foraging salmonids and were separated from each other by at least two pools.…”

Section: Methodsmentioning

confidence: 99%

Seasonal growth potential of Oncorhynchus mykiss in streams with contrasting prey phenology and streamflow

et al. 2022

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The growth of any organism depends on habitat conditions, food availability, and their seasonal interactions. Yet in the vast literature on Pacific salmon (Oncorhynchus), the seasonal interaction between habitat conditions and food availability has received relatively little attention. We examined juvenile Oncorhynchus mykiss rearing, physical habitat, and resource phenologies in two Mediterranean coastal streams-one perennial, cool, and shaded and the other intermittent, seasonally warm, and sunny. We used a bioenergetic model to investigate the timing and magnitude of growth potential for drift-foraging O. mykiss during the spring and summer in both systems. Growth potential peaked at least 2 months earlier in the intermittent stream than in the perennial stream. By early summer (June), growth potential had declined in the intermittent stream, whereas growth rates were peaking in the perennial stream. However, the mid-July lipid content of juvenile O. mykiss in the intermittent stream was nearly twice that of fish in the perennial stream. By late summer (August), foraging profitability declined in both streams, as abiotic conditions in the intermittent stream approached lethal. In contrast, the perennial stream maintained suitable abiotic conditions even though the growth rate was low. We suggest that the divergent resource phenologies and seasonal mortality risks experienced by anadromous O. mykiss rearing in these streams could drive diversification of traits governing size, age, and timing of outmigration.

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Section: Methodsmentioning

confidence: 99%

Seasonal growth potential of Oncorhynchus mykiss in streams with contrasting prey phenology and streamflow

et al. 2022

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“…Each study reach contained four riffle-pool habitat units which served as replicates, resulting in eight “control” units and eight “impact” units (Figure 2). The riffle-pool unit is a ubiquitous geomorphic feature in alluvial streams with slopes between 0.5% and 2% (Leopold and Wolman 1957) and provides a discrete habitat unit for evaluating juvenile salmonid rearing and foraging during the low-flow period (Rossi et al 2021). Study site selection was constrained by landowner access and channel confinement in the upper reaches of Porter Creek and was, therefore, not random.…”

Section: Methodsmentioning

confidence: 99%

“…Water level loggers were mounted to rebar and installed near the pool maximum depth (Figure 2). Depth was measured where the thalweg bisects the downstream riffle crest of each pool, a point known as the ‘riffle crest thalweg’ (RCT) (Rossi et al 2021). RCT depth serves as an indicator of hydraulic connectivity and has been shown to be correlated with dissolved oxygen concentrations and fish behavior (Rossi et al 2021, Rossi et al 2021b).…”

Section: Methodsmentioning

confidence: 99%

“…Depth was measured where the thalweg bisects the downstream riffle crest of each pool, a point known as the ‘riffle crest thalweg’ (RCT) (Rossi et al 2021). RCT depth serves as an indicator of hydraulic connectivity and has been shown to be correlated with dissolved oxygen concentrations and fish behavior (Rossi et al 2021, Rossi et al 2021b). The elevation of the RCT was surveyed relative to the elevation of the water level logger and staff plate to allow for a conversion between continuous pool stage and continuous RCT depth (Figure 2).…”

Section: Methodsmentioning

confidence: 99%

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Flow augmentation from off-channel storage improves salmonid habitat and survival

Rossi

Obedzinski

Pneh

et al. 2023

Preprint

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In the Western United States, juvenile salmon and steelhead are especially vulnerable to streamflow depletion in the dry season. Releasing water from off-channel storage is a method of streamflow augmentation increasingly used to offset impacts of anthropogenic flow alteration. However, to date, no studies have evaluated the effects of these small-scale flow augmentations on salmonids. Here we quantify the effects of one such augmentation project on habitat connectivity, water quality, invertebrate drift, juvenile salmonid movement and survival. Our study took place in a Northern California stream and included an unusually wet summer (2019) and a more typical dry summer (2020). We found that differences in ambient streamflows between the two years mediated the physical and ecological effects of a 13.9 L/s augmentation treatment. In the dry year, flow augmentation significantly improved dissolved oxygen and habitat connectivity at sites > 1.5 km downstream from the point of augmentation and had a marginal warming effect on stream temperature. During the wet year, both dissolved oxygen and water temperature effects were negligible. In both years, augmentation had a small but positive effect on invertebrate drift. Inter-pool movement of juvenile steelhead (Oncorhynchus mykiss) and stocked Coho Salmon (O. kisutch) increased due to augmentation during the dry summer. Flow augmentation also increased the survival probability for salmonids, with a larger effect during the dry summer (24% higher survival for Coho and 20% higher for steelhead), than during the wet summer (when no effect was observed for steelhead survival and Coho Salmon survival increased by 11%). This study indicates that appropriately designed and timed flow augmentations can improve conditions for rearing salmonids in small streams, particularly during dry years. More broadly it provides empirical evidence that efforts to restore summer streamflow in small, salmon-bearing streams can yield significant ecological benefits.

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“…Given that channels may have large local variations in slope (e.g., between riffles and pools), they can be easily biased by a small number of geomorphic units (e.g., deep pools). Using the gradient measured between riffle crests has the advantage of being more relevant for hydraulic calculations and models, as the riffle crest gradient approximates the water surface slope at high flows and provides a consistent measure in the field as it is easy to identify (Rossi et al, 2021). Care should also be taken to measure the gradient over a sufficiently long distance, typically advised over at least 20 channel widths to obtain a representative average reach gradient (Rosgen, 1994).…”

Section: Recommendations For Measuring Geomorphology In River Assessm...mentioning

confidence: 99%

Measuring geomorphology in river assessment procedures 2: Recommendations for supporting river management goals

Papangelakis

Hassan

Luzi

et al. 2023

J American Water Resour Assoc

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Fluvial geomorphology, which describes the form and processes of rivers, is increasingly being incorporated into river assessment procedures. However, the complexity of geomorphic processes makes a single universal and standardized assessment protocol a challenging and possibly impractical task. In this paper, we present a set of recommendations for choosing appropriate river assessment procedures and measuring geomorphic indicators to effectively capture important geomorphic processes required to support river management goals. We outline steps for building a river assessment procedure based on an adaptive approach rather than a one‐size‐fits‐all approach, where the geomorphic indicators, spatial and temporal scale, and methodologies used are carefully chosen based on the goals of the management project; the assessment aims to support. Guidance for choosing the appropriate geomorphic indicators is based on their significance (usefulness in characterizing the system), ease of measurement, and temporal scale needs. We also present recommendations on measurement techniques for each indicator while highlighting recent technological and methodological advancements that help overcome resource challenges often faced in river assessment. Given the wealth of scientific and technological developments in the field of geomorphology, it is possible to improve how geomorphic form and function are measured and incorporated into river assessments that support watershed management goals.

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Hydraulic Properties of the Riffle Crest and Applications for Stream Ecosystem Management

Cited by 6 publications

References 57 publications

Seasonal growth potential of Oncorhynchus mykiss in streams with contrasting prey phenology and streamflow

Seasonal growth potential of Oncorhynchus mykiss in streams with contrasting prey phenology and streamflow

Flow augmentation from off-channel storage improves salmonid habitat and survival

Measuring geomorphology in river assessment procedures 2: Recommendations for supporting river management goals

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