Hydrogeomorphic Scaling and Ecohydraulics for Designing Rescaled Channel and Floodplain Geometry in Regulated Gravel–Cobble Bed Rivers for Pacific Salmon Habitat

Brown, Rocko A.

doi:10.3390/w14040670

Cited by 6 publications

(2 citation statements)

References 186 publications

(336 reference statements)

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“…Combining riffle‐pool theories with mountain river restoration strategies provides important technology to promote mountain river ecosystem management. Riffle‐pool sequences were widely applied in channel restoration and river ecohydraulic rehabilitation schemes (Brown, 2022; Clifford et al, 2002; Movahedi et al, 2020). They were employed in mountain rivers to resist riverbed incision for better stability (Chapuis et al, 2014; Hassan et al, 2022; MacVicar & Roy, 2011).…”

Section: Discussionmentioning

confidence: 99%

Evaluating the physical habitat of riffle‐pool design in support of river habitat protection and rehabilitation

Wang,

Yang,

Bao

et al. 2023

Ecohydrology

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Riffle‐pool constructions are common practice in river management and fish conservation, but insufficient science exists to guide objective design of riffle‐pool. Understanding the spatial design of a riffle‐pool in river systems has significant value because it can provide important information to ameliorate aquatic species decline. In this study, six types of riffle‐pool structures were designed to assess hydrodynamic and riverbed morphology effects on stream habitat status. A two‐dimensional ecohydraulic model was used to assess the roles of different riffle‐pool designs in river habitat conditions. The natural flow condition and three types of flood flow conditions were applied to the six types of riffle‐pool structures to evaluate the habitat quality and the sustainability of the riffle‐pool design in mountain rivers. The long‐term impacts of the hydrodynamic and hydromorphology conditions on river physical habitat status were also analysed. The results indicate substantial differences in habitat quality among six riffle‐pool structures. It was found that narrow riffle‐pool construction yielded the best performance for the fish habitat, which had the best habitat quality among six riffle‐pool designs with the smallest pool area. In the same riffle‐pool structure, the habitat suitability in the riffle‐pool sequence will primarily increase more rapidly and then decrease gradually along with the discharge increase. Under the flood discharge scenarios, low flood discharge could improve riffle‐pool habitat quality, while high flood discharge could fragment the riffle‐pool habitat quality further. The long‐term hydrodynamic conditions have the same effects on all six cases. Overall, low discharge and smaller pool design would be beneficial to the river system, which could help maintain habitat diversity of mountain rivers. This analysis could provide valuable information for river management and decision‐making, which could assist in designing better mountain river habitats to promote conservation and rehabilitation of endangered biota.

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Section: Discussionmentioning

confidence: 99%

Evaluating the physical habitat of riffle‐pool design in support of river habitat protection and rehabilitation

Wang,

Yang,

Bao

et al. 2023

Ecohydrology

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“…Models are widely used in aquatic habitat studies (Brown & Pasternack, 2009; Kammel et al., 2016; May et al., 2009; May & Pryor, 2016) and in process‐based, bioenergetic analyses of flow‐species interactions (Jowett et al., 2021). Multi‐dimensional models are key tools in river restoration design (Brown, 2022) and also provide a means of quantifying morphodynamic processes in channels and riparian zones following restoration (Vargas‐Luna et al., 2018).…”

Section: Introductionmentioning

confidence: 99%

Evaluating the Sensitivity of Multi‐Dimensional Model Predictions of Salmon Habitat to the Source of Remotely Sensed River Bathymetry

Harrison

Legleiter

Sridharan

et al. 2022

Water Resources Research

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Multi‐dimensional numerical models are fundamental tools for investigating biophysical processes in aquatic ecosystems. Remote sensing techniques increase the feasibility of applying such models at riverscape scales, but tests of model performance on large rivers have been limited. We evaluated the potential to develop two‐dimensional (2D) and three‐dimensional (3D) hydrodynamic models for a 1.6‐km reach of a large gravel‐bed river using three sources of remotely sensed river bathymetry. We estimated depth from hyperspectral image data acquired from conventional and uncrewed aircraft and multispectral satellite imagery. Our results indicated that modeled water depth errors were similar between 2D and 3D models, with depth residuals that were comparable to the uncertainty associated with the bathymetry used as input. We found good agreement between measured and modeled depth‐averaged velocities generated by 2D and 3D models, while 3D models provided superior predictions of near‐bed velocities. We found that optimal model performance occurred for lower flow resistance values than previously reported in the literature, possibly as a consequence of the high‐resolution bathymetry used as model input. Model predictions of winter‐run Chinook salmon (Oncorhynchus tshawytscha) spawning and rearing habitat were not sensitive to the source of bathymetric information, but bioenergetic predictions related to adult holding costs were influenced by the input bathymetry. Our results suggest that hyperspectral imagery acquired from piloted and/or uncrewed aircraft can be used to map the bathymetry of clear‐flowing, relatively shallow large rivers with sufficient accuracy to support multi‐dimensional flow model development; models developed from multispectral satellite imagery had more limited predictive capability.

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Disruption of natural disturbance regime decouples habitat and life stage in a keystone species

Merz,

Brown,

Sellheim

et al. 2024

Ecosphere

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Anthropogenic disturbance of stream ecosystems, often chronic in nature, has been studied extensively. However, when disturbance is driven by more than one resource policy over many decades, feedback between habitat evolution and biological adaptation can be disrupted and ecological function affected in unforeseen ways. We analyzed over 100 years of Chinook salmon (Oncorhynchus tshawytscha) length frequency trends associated with fisheries management and changes in available spawning substrate (habitat) linked to flow regulation in a highly altered California river. Over time, salmon lengths generally decreased, fluctuating with exploitation (ocean harvest) and hatchery production rates. Female size reduction, coupled with a degrading and coarsening channel, and perching peripheral habitat related to past mining activity, indicates available spawning substrate may be too large to support the current salmon population. Assuming a salmon can move material ~10% of her body length, length frequency data and current substrate size distribution suggest that increasing salmon sizes to historic distributions could increase available spawning habitat by as much as 13%. Alternatively, decreasing spawning substrate size could support a greater portion of the current population. To test the latter hypothesis and inform future management actions, we monitored two spawning riffles where large and small gravel was placed on top of a cobble. We observed an immediate spawning activity increase that was more pronounced where smaller gravel was deposited. Following a decade of habitat decline, the two sites were both replenished with medium gravel. Elevated spawning use occurred immediately at both sites, commensurate with this intermediate size, further supporting our hypotheses. Sediment coarsening and habitat disconnect below dams, combined with reduced salmon size, indicate the natural spawning process may be decoupled from available habitat below dams in the foreseeable future without continuous intervention. Actively managing salmon population demographics through modified hatchery and size‐selective harvest practices and developing a coarse sediment budget with size‐appropriate material for regulated anadromous rivers could produce immediate benefits for ecosystem services, including salmon populations. However, these management actions will require continued maintenance and informed socio‐ecological goals to remain successful.

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Hydrogeomorphic Scaling and Ecohydraulics for Designing Rescaled Channel and Floodplain Geometry in Regulated Gravel–Cobble Bed Rivers for Pacific Salmon Habitat

Cited by 6 publications

References 186 publications

Evaluating the physical habitat of riffle‐pool design in support of river habitat protection and rehabilitation

Evaluating the physical habitat of riffle‐pool design in support of river habitat protection and rehabilitation

Evaluating the Sensitivity of Multi‐Dimensional Model Predictions of Salmon Habitat to the Source of Remotely Sensed River Bathymetry

Disruption of natural disturbance regime decouples habitat and life stage in a keystone species

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