Pub Date : 2021-06-30DOI: 10.1080/24705357.2021.1938251
Bernhard Wegscheider, T. Linnansaari, Mouhamed Ndong, K. Haralampides, A. St‐Hilaire, M. Schneider, R. Curry
Physical habitat models represent a widely used tool in river management, yet, there is a growing consensus—particularly for large rivers—that fundamental principles have limits, and it is evident ...
{"title":"Fish habitat modelling in large rivers: combining expert opinion and hydrodynamic modelling to inform river management","authors":"Bernhard Wegscheider, T. Linnansaari, Mouhamed Ndong, K. Haralampides, A. St‐Hilaire, M. Schneider, R. Curry","doi":"10.1080/24705357.2021.1938251","DOIUrl":"https://doi.org/10.1080/24705357.2021.1938251","url":null,"abstract":"Physical habitat models represent a widely used tool in river management, yet, there is a growing consensus—particularly for large rivers—that fundamental principles have limits, and it is evident ...","PeriodicalId":93201,"journal":{"name":"Journal of ecohydraulics","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73600594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-29DOI: 10.1080/24705357.2021.1938255
G. Lama, A. Errico, V. Pasquino, S. Mirzaei, F. Preti, G. Chirico
Abstract One of the main purposes of Ecohydraulics is to predict the effects of riparian vegetation on aquatic ecosystems within real water channels. The interaction between water flow and riparian plants significantly affects flow dynamics, hydraulic conveyance, and water quality of vegetated water bodies. This study aimed at quantifying analytically the uncertainty in flow average velocity estimations associated with the uncertainty of Leaf Area Index (LAI) of Phragmites australis (Cav.) Trin. ex Steudel covering a vegetated channel. The impacts of this species on the hydrodynamics of vegetated streams are far to be completely understood. The uncertainty in flow average velocity was assessed through the first-order second-moment statistical method, by comparing direct and indirect LAI measurements of mature Phragmites australis plants. Indirect LAI values were obtained using the LICOR® LAI-2000 Plant Canopy Analyzer device. The results of this study suggest that the uncertainties in flow average velocity estimations are comparable to those associated with experimental measurements of streamwise velocity components retrieved in real vegetated flows fully covered by mature Phragmites australis plants.
{"title":"Velocity uncertainty quantification based on Riparian vegetation indices in open channels colonized by Phragmites australis","authors":"G. Lama, A. Errico, V. Pasquino, S. Mirzaei, F. Preti, G. Chirico","doi":"10.1080/24705357.2021.1938255","DOIUrl":"https://doi.org/10.1080/24705357.2021.1938255","url":null,"abstract":"Abstract One of the main purposes of Ecohydraulics is to predict the effects of riparian vegetation on aquatic ecosystems within real water channels. The interaction between water flow and riparian plants significantly affects flow dynamics, hydraulic conveyance, and water quality of vegetated water bodies. This study aimed at quantifying analytically the uncertainty in flow average velocity estimations associated with the uncertainty of Leaf Area Index (LAI) of Phragmites australis (Cav.) Trin. ex Steudel covering a vegetated channel. The impacts of this species on the hydrodynamics of vegetated streams are far to be completely understood. The uncertainty in flow average velocity was assessed through the first-order second-moment statistical method, by comparing direct and indirect LAI measurements of mature Phragmites australis plants. Indirect LAI values were obtained using the LICOR® LAI-2000 Plant Canopy Analyzer device. The results of this study suggest that the uncertainties in flow average velocity estimations are comparable to those associated with experimental measurements of streamwise velocity components retrieved in real vegetated flows fully covered by mature Phragmites australis plants.","PeriodicalId":93201,"journal":{"name":"Journal of ecohydraulics","volume":"25 1","pages":"71 - 76"},"PeriodicalIF":0.0,"publicationDate":"2021-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75700798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-15DOI: 10.1080/24705357.2020.1871307
D. Courret, P. Baran, M. Larinier
Abstract Hydropeaking by hydroelectric facilities generates sudden changes in river flows and can affect the composition, abundance and structure of fish and invertebrate populations over long distances. To assess the level of hydrological alteration, as a factor of risk of biological impacts, a synthetic indicator was developed. Based on the analysis of 97 hydrometric stations and 1575 years of unaltered flow data, rates of change in flow were calculated. Formulas representing the fastest natural variations, depending on the mean stream flow, the type of variation (increase or decrease) and the range of variation were established. Based on the analysis of 80 hydrometric stations and 491 years of flow data affected by hydropeaking, a method was developed to identify hydropeaks, essentially defined as variations with a rate of change greater than the maximum natural value computed using the formulas. A synthetic indicator differentiating five levels of hydrological alteration was developed using linear discriminant analysis based on five parameters characterizing hydropeaking regimes. Examples show that this indicator is sensitive to changes in the management of hydroelectric facilities and provides information on the spatial and temporal evolutions in hydropeaking regimes, including the progressive attenuation during downstream propagation.
{"title":"An indicator to characterize hydrological alteration due to hydropeaking","authors":"D. Courret, P. Baran, M. Larinier","doi":"10.1080/24705357.2020.1871307","DOIUrl":"https://doi.org/10.1080/24705357.2020.1871307","url":null,"abstract":"Abstract Hydropeaking by hydroelectric facilities generates sudden changes in river flows and can affect the composition, abundance and structure of fish and invertebrate populations over long distances. To assess the level of hydrological alteration, as a factor of risk of biological impacts, a synthetic indicator was developed. Based on the analysis of 97 hydrometric stations and 1575 years of unaltered flow data, rates of change in flow were calculated. Formulas representing the fastest natural variations, depending on the mean stream flow, the type of variation (increase or decrease) and the range of variation were established. Based on the analysis of 80 hydrometric stations and 491 years of flow data affected by hydropeaking, a method was developed to identify hydropeaks, essentially defined as variations with a rate of change greater than the maximum natural value computed using the formulas. A synthetic indicator differentiating five levels of hydrological alteration was developed using linear discriminant analysis based on five parameters characterizing hydropeaking regimes. Examples show that this indicator is sensitive to changes in the management of hydroelectric facilities and provides information on the spatial and temporal evolutions in hydropeaking regimes, including the progressive attenuation during downstream propagation.","PeriodicalId":93201,"journal":{"name":"Journal of ecohydraulics","volume":"12 1","pages":"139 - 156"},"PeriodicalIF":0.0,"publicationDate":"2021-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85697737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-15DOI: 10.1080/24705357.2021.1892547
Chendi Zhang, Mengzhen Xu, F. Lei, Jiahao Zhang, G. Kattel, Yongjie Duan
Abstract The naked carp (Gymnocypris przewalskii) plays a central role in the ecosystem of the Qinghai Lake, the largest saline-alkaline lake in China. The adult naked carp migrates in large groups with high population density annually from the Qinghai Lake to the upstream freshwater rivers to spawn. Nevertheless, the responsiveness of the fish to local abiotic cues in the form of distribution patterns during migration across the riverine-lacustrine network of the Qinghai Lake region remains unknown. This knowledge gap has reduced efficiency in fish conservation and management efforts in the region. To address this issue, we carried out two field surveys from June to August, 2018, with the aid of unmanned aerial vehicles to a 200-m long back channel characterizing diverse morphological and hydraulic features on the migration route. Combined structure from motion photogrammetry and deep neural network techniques were used to establish a new workflow for detecting and extracting the profiles of fish individuals in large schools. The spatio-temporal distribution pattern of the fish demonstrated that the naked carp was attracted by hydraulic environments with high flow velocity or deep-water during migration. The diurnal variation of temperature and light could alter the preference for hydraulic environments of the fish. Our results highlight the crucial role of the interactions between river morphology and hydraulics, water temperature and light on the migration behaviours of the naked carp.
{"title":"Spatio-temporal distribution of Gymnocypris przewalskii during migration with UAV-based photogrammetry and deep neural network","authors":"Chendi Zhang, Mengzhen Xu, F. Lei, Jiahao Zhang, G. Kattel, Yongjie Duan","doi":"10.1080/24705357.2021.1892547","DOIUrl":"https://doi.org/10.1080/24705357.2021.1892547","url":null,"abstract":"Abstract The naked carp (Gymnocypris przewalskii) plays a central role in the ecosystem of the Qinghai Lake, the largest saline-alkaline lake in China. The adult naked carp migrates in large groups with high population density annually from the Qinghai Lake to the upstream freshwater rivers to spawn. Nevertheless, the responsiveness of the fish to local abiotic cues in the form of distribution patterns during migration across the riverine-lacustrine network of the Qinghai Lake region remains unknown. This knowledge gap has reduced efficiency in fish conservation and management efforts in the region. To address this issue, we carried out two field surveys from June to August, 2018, with the aid of unmanned aerial vehicles to a 200-m long back channel characterizing diverse morphological and hydraulic features on the migration route. Combined structure from motion photogrammetry and deep neural network techniques were used to establish a new workflow for detecting and extracting the profiles of fish individuals in large schools. The spatio-temporal distribution pattern of the fish demonstrated that the naked carp was attracted by hydraulic environments with high flow velocity or deep-water during migration. The diurnal variation of temperature and light could alter the preference for hydraulic environments of the fish. Our results highlight the crucial role of the interactions between river morphology and hydraulics, water temperature and light on the migration behaviours of the naked carp.","PeriodicalId":93201,"journal":{"name":"Journal of ecohydraulics","volume":"72 1","pages":"42 - 57"},"PeriodicalIF":0.0,"publicationDate":"2021-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87409403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-13DOI: 10.1080/24705357.2020.1869916
Márcio S. Roth, Ch. Jähnel, J. Stamm, L. Schneider
Abstract Fishways are an important link for the reestablishment of river continuity, interrupted by transverse structures e.g. weirs, dams and hydropower plants. The meander fishway and vertical slot fishway are two types commonly constructed in Germany, which create distinctive flow regimes to allow upstream passage. Nonetheless minor environmental or constructional alterations create unforeseen flow regimes, whose impact on fish behaviour is still uncertain. One approach is to obtain different flow aspects for fish by evaluating numerous parameters with the IPOS-framework in laboratory experiments. The framework provides various identification parameters and methods, which must be considered with regard to fish behaviour. This paper expands the experimental approach by using numerical simulations with OpenFOAM on one meander and two vertical slot fishways and employs the evaluation methods stated in the IPOS-framework. The results shows clear differences between the fishways, providing an advanced numerical evaluation method to objectively compare turbulent flows in the models. The 3D-hydronumerical evaluation of 1:1 scaled fishways using the IPOS-framework is a novelty so far and can be used to improve present and future fishway constructions.
{"title":"Turbulent eddy identification of a meander and vertical-slot fishways in numerical models applying the IPOS-framework","authors":"Márcio S. Roth, Ch. Jähnel, J. Stamm, L. Schneider","doi":"10.1080/24705357.2020.1869916","DOIUrl":"https://doi.org/10.1080/24705357.2020.1869916","url":null,"abstract":"Abstract Fishways are an important link for the reestablishment of river continuity, interrupted by transverse structures e.g. weirs, dams and hydropower plants. The meander fishway and vertical slot fishway are two types commonly constructed in Germany, which create distinctive flow regimes to allow upstream passage. Nonetheless minor environmental or constructional alterations create unforeseen flow regimes, whose impact on fish behaviour is still uncertain. One approach is to obtain different flow aspects for fish by evaluating numerous parameters with the IPOS-framework in laboratory experiments. The framework provides various identification parameters and methods, which must be considered with regard to fish behaviour. This paper expands the experimental approach by using numerical simulations with OpenFOAM on one meander and two vertical slot fishways and employs the evaluation methods stated in the IPOS-framework. The results shows clear differences between the fishways, providing an advanced numerical evaluation method to objectively compare turbulent flows in the models. The 3D-hydronumerical evaluation of 1:1 scaled fishways using the IPOS-framework is a novelty so far and can be used to improve present and future fishway constructions.","PeriodicalId":93201,"journal":{"name":"Journal of ecohydraulics","volume":"47 1","pages":"124 - 143"},"PeriodicalIF":0.0,"publicationDate":"2021-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90696346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-03-28DOI: 10.1080/24705357.2020.1820913
J. Ramos, J. Gracia-Sánchez, L. Marrufo-Vázquez
Abstract Mangrove lands are becoming livestock and agriculture systems generating a reduction in estuary areas and an increase in the sediments transported towards the sea. This situation is prevalent in Marismas Nacionales, estuary of the San Pedro-Mezquital River, Mexico. Using satellite imaging, the deforestation rate for both forest and mangrove, as well as the morphologic change of the river and its floodplain were estimated. Remote sensing techniques were applied to achieve an integrated analysis of land change. The loss of forest was around 30% from the 80’s to the 90’s, and was more severe and constant in the middle of the basin. In this area, results show that the sediment increase directly affects water bodies and mangroves downstream, showing a decrease of 30% and 20%, respectively. The main land change was the conversion into agricultural areas, which affected coastal lands with large changes in sediment size and quality. The latter is due to the residual amounts from the anthropogenic economicactivities which form great water-stable aggregates by modifying the mangroves soil characteristics. This change of soil properties is related to the loss of capability to maintain biotic communities, thus ecosystems die gradually. However, the ecosystem could recover with active human participation.
{"title":"Loss of mangroves as a consequence of the anthropic interactions downstream a river basin","authors":"J. Ramos, J. Gracia-Sánchez, L. Marrufo-Vázquez","doi":"10.1080/24705357.2020.1820913","DOIUrl":"https://doi.org/10.1080/24705357.2020.1820913","url":null,"abstract":"Abstract Mangrove lands are becoming livestock and agriculture systems generating a reduction in estuary areas and an increase in the sediments transported towards the sea. This situation is prevalent in Marismas Nacionales, estuary of the San Pedro-Mezquital River, Mexico. Using satellite imaging, the deforestation rate for both forest and mangrove, as well as the morphologic change of the river and its floodplain were estimated. Remote sensing techniques were applied to achieve an integrated analysis of land change. The loss of forest was around 30% from the 80’s to the 90’s, and was more severe and constant in the middle of the basin. In this area, results show that the sediment increase directly affects water bodies and mangroves downstream, showing a decrease of 30% and 20%, respectively. The main land change was the conversion into agricultural areas, which affected coastal lands with large changes in sediment size and quality. The latter is due to the residual amounts from the anthropogenic economicactivities which form great water-stable aggregates by modifying the mangroves soil characteristics. This change of soil properties is related to the loss of capability to maintain biotic communities, thus ecosystems die gradually. However, the ecosystem could recover with active human participation.","PeriodicalId":93201,"journal":{"name":"Journal of ecohydraulics","volume":"37 1","pages":"71 - 80"},"PeriodicalIF":0.0,"publicationDate":"2021-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86779561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-03-15DOI: 10.1080/24705357.2020.1856008
A. Barillier, L. Bêche, J. Malavoi, V. Gouraud
Abstract Downstream of hydroelectric plants, hydropeaking can cause frequent flow variations, resulting in habitat modifications (e.g. hydraulics, reach morphology, temperature, water quality), which can impact organisms (stranding, dewatering, forced drift, growth disturbances) and ultimately may have negative and lasting impacts on biological communities, reducing resilience. Nevertheless, the severity of habitat disturbances vary depending on other existing pressures and local site conditions, which need to be taken into account to achieve effective hydropeaking mitigation. Preserving hydropower flexibility is also a priority to ensure the stability of electric systems without recourse to more polluting alternatives. Given these apparently opposing objectives, we propose a consensual technico-economic framework to guarantee the feasibility and effectiveness of site-specific hydropeaking mitigation, based on our experience as a hydropower operator and a literature review. While existing tools (such as habitat models) can be used to predict expected local effects of proposed mitigation and compare scenarios, predicting biological community responses is not currently possible (lack of in-situ evaluations of mitigation efficacy). These uncertainties and complex socio-ecosystems necessitate a forward-looking global approach that accounts for climate change, multi-purpose water use and electric system requirements, combined with site-specific analyses of the relative importance of hydropeaking impacts with respect to other pressures.
{"title":"Identification of effective hydropeaking mitigation measures: are hydraulic habitat models sufficient in a global approach?","authors":"A. Barillier, L. Bêche, J. Malavoi, V. Gouraud","doi":"10.1080/24705357.2020.1856008","DOIUrl":"https://doi.org/10.1080/24705357.2020.1856008","url":null,"abstract":"Abstract Downstream of hydroelectric plants, hydropeaking can cause frequent flow variations, resulting in habitat modifications (e.g. hydraulics, reach morphology, temperature, water quality), which can impact organisms (stranding, dewatering, forced drift, growth disturbances) and ultimately may have negative and lasting impacts on biological communities, reducing resilience. Nevertheless, the severity of habitat disturbances vary depending on other existing pressures and local site conditions, which need to be taken into account to achieve effective hydropeaking mitigation. Preserving hydropower flexibility is also a priority to ensure the stability of electric systems without recourse to more polluting alternatives. Given these apparently opposing objectives, we propose a consensual technico-economic framework to guarantee the feasibility and effectiveness of site-specific hydropeaking mitigation, based on our experience as a hydropower operator and a literature review. While existing tools (such as habitat models) can be used to predict expected local effects of proposed mitigation and compare scenarios, predicting biological community responses is not currently possible (lack of in-situ evaluations of mitigation efficacy). These uncertainties and complex socio-ecosystems necessitate a forward-looking global approach that accounts for climate change, multi-purpose water use and electric system requirements, combined with site-specific analyses of the relative importance of hydropeaking impacts with respect to other pressures.","PeriodicalId":93201,"journal":{"name":"Journal of ecohydraulics","volume":"1 1","pages":"172 - 185"},"PeriodicalIF":0.0,"publicationDate":"2021-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84447391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-03-02DOI: 10.1080/24705357.2020.1839799
I. Jowett, J. Hayes, Jason R. Neuswanger
Abstract Software is now available to apply a salmonid bioenergetic drift-foraging model to generate values of net energy intake (NEI) over a range of water depths and velocities. The predictions can be used to build univariate “habitat” suitability curves or multivariate “habitat” selection models for use in instream habitat modelling programs. Capture success and swimming cost sub-models are basic components of the bioenergetic model and there is a need to understand their influence of NEI predictions. Examination of the swimming cost sub-models showed a surprising amount of variation between species and models and this was attributed to the amount and range of data used for their derivation and the different methods of formulating the swimming cost equations. Predictions of optimal velocity for large fish (>96 g) was influenced by the choice of swimming cost sub-model but optimal velocities for smaller fish were dependent on the capture success sub-model. More research is needed to validate the capture success sub-model, especially for larger fish sizes. Swimming costs while intercepting prey, and the cost of swimming in natural streams with turbulence, are other factors that remain uncertain.
{"title":"Salmonid bioenergetic drift-foraging: swimming costs and capture success","authors":"I. Jowett, J. Hayes, Jason R. Neuswanger","doi":"10.1080/24705357.2020.1839799","DOIUrl":"https://doi.org/10.1080/24705357.2020.1839799","url":null,"abstract":"Abstract Software is now available to apply a salmonid bioenergetic drift-foraging model to generate values of net energy intake (NEI) over a range of water depths and velocities. The predictions can be used to build univariate “habitat” suitability curves or multivariate “habitat” selection models for use in instream habitat modelling programs. Capture success and swimming cost sub-models are basic components of the bioenergetic model and there is a need to understand their influence of NEI predictions. Examination of the swimming cost sub-models showed a surprising amount of variation between species and models and this was attributed to the amount and range of data used for their derivation and the different methods of formulating the swimming cost equations. Predictions of optimal velocity for large fish (>96 g) was influenced by the choice of swimming cost sub-model but optimal velocities for smaller fish were dependent on the capture success sub-model. More research is needed to validate the capture success sub-model, especially for larger fish sizes. Swimming costs while intercepting prey, and the cost of swimming in natural streams with turbulence, are other factors that remain uncertain.","PeriodicalId":93201,"journal":{"name":"Journal of ecohydraulics","volume":"25 1","pages":"186 - 197"},"PeriodicalIF":0.0,"publicationDate":"2021-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76016339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-09DOI: 10.1080/24705357.2020.1840313
J. Boudreault, A. St‐Hilaire, F. Chebana, N. Bergeron
Abstract In this paper, a new fish habitat modelling approach is introduced using the full probability density functions (PDF), rather than single measurements or central tendency metrics, to describe each predictor. To model habitat selection using PDFs, functional regression models (FRM) are used to allow for the inclusion of curves or functions (smoothed empirical PDFs) in regression models compared to scalars or vectors in classical contexts. The benefits of FRM are exemplified by comparing results with those obtained using generalized additive models (GAM), one of the most recent and performing models in the field. Abundance of juvenile Atlantic salmon sampled at 26 sites (75 m-long x river width) of the Sainte-Marguerite River (Quebec, Canada) was modelled with PDFs of four potential predictors: flow velocity, water depth, substrate size and water temperature. The latter has been less frequently used in habitat modelling and the results showed that it was the most significant predictor. Overall, FRM explained more of the variability in habitat selection than GAM (+14.9% for fry and +8.1% for 1+ parr), mainly due to their ability to use complete distributions of the habitat variables rather than aggregated values (mean). A leave-one-out cross validation showed that both GAM and FRM had similar performance to predict fish abundance. The use of FRM in fish habitat modelling is innovative and its potential should be further developed, especially in the current context where habitat variables are becoming increasingly easy to obtain due to rapid progress of remote measurement techniques.
{"title":"Modelling fish physico-thermal habitat selection using functional regression","authors":"J. Boudreault, A. St‐Hilaire, F. Chebana, N. Bergeron","doi":"10.1080/24705357.2020.1840313","DOIUrl":"https://doi.org/10.1080/24705357.2020.1840313","url":null,"abstract":"Abstract In this paper, a new fish habitat modelling approach is introduced using the full probability density functions (PDF), rather than single measurements or central tendency metrics, to describe each predictor. To model habitat selection using PDFs, functional regression models (FRM) are used to allow for the inclusion of curves or functions (smoothed empirical PDFs) in regression models compared to scalars or vectors in classical contexts. The benefits of FRM are exemplified by comparing results with those obtained using generalized additive models (GAM), one of the most recent and performing models in the field. Abundance of juvenile Atlantic salmon sampled at 26 sites (75 m-long x river width) of the Sainte-Marguerite River (Quebec, Canada) was modelled with PDFs of four potential predictors: flow velocity, water depth, substrate size and water temperature. The latter has been less frequently used in habitat modelling and the results showed that it was the most significant predictor. Overall, FRM explained more of the variability in habitat selection than GAM (+14.9% for fry and +8.1% for 1+ parr), mainly due to their ability to use complete distributions of the habitat variables rather than aggregated values (mean). A leave-one-out cross validation showed that both GAM and FRM had similar performance to predict fish abundance. The use of FRM in fish habitat modelling is innovative and its potential should be further developed, especially in the current context where habitat variables are becoming increasingly easy to obtain due to rapid progress of remote measurement techniques.","PeriodicalId":93201,"journal":{"name":"Journal of ecohydraulics","volume":"175 1","pages":"105 - 120"},"PeriodicalIF":0.0,"publicationDate":"2021-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83779122","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-01DOI: 10.1080/24705357.2020.1831415
C. Rachelly, K. Mathers, C. Weber, V. Weitbrecht, R. Boes, D. Vetsch
Abstract Habitats that mitigate the effects of a disturbance event (e.g. flood) are referred to as refugia. Their occurrence in heavily impacted river systems is often limited, and their restoration rarely pursued. This paper presents the results of a combined laboratory and numerical modeling study to assess flood refugia availability to mobile aquatic organisms in the context of river restoration and dynamic river widening. We used a calibrated 2D hydrodynamic model based on eight topographies obtained in laboratory experiments to assess refugia availability by analyzing the hydro-morphological conditions under varying sediment supply. Overall, sediment equilibrium sustains more complex hydro-morphological conditions with low bed shear stress zones being maintained during elevated discharges. Furthermore, our results suggest that the floodplain is an important potential refuge that becomes accessible for discharges with a return period of approximately one year. Conversely, sediment deficit results in a homogeneous flow field with steadily increasing hydraulic forces for high flows and impaired lateral connectivity except for very large flood events of a 30- to 100-year return period. Dynamic river widening implemented in a channel with sediment equilibrium conditions as opposed to a sediment deficit is thus more likely to provide flood refugia.
{"title":"How does sediment supply influence refugia availability in river widenings?","authors":"C. Rachelly, K. Mathers, C. Weber, V. Weitbrecht, R. Boes, D. Vetsch","doi":"10.1080/24705357.2020.1831415","DOIUrl":"https://doi.org/10.1080/24705357.2020.1831415","url":null,"abstract":"Abstract Habitats that mitigate the effects of a disturbance event (e.g. flood) are referred to as refugia. Their occurrence in heavily impacted river systems is often limited, and their restoration rarely pursued. This paper presents the results of a combined laboratory and numerical modeling study to assess flood refugia availability to mobile aquatic organisms in the context of river restoration and dynamic river widening. We used a calibrated 2D hydrodynamic model based on eight topographies obtained in laboratory experiments to assess refugia availability by analyzing the hydro-morphological conditions under varying sediment supply. Overall, sediment equilibrium sustains more complex hydro-morphological conditions with low bed shear stress zones being maintained during elevated discharges. Furthermore, our results suggest that the floodplain is an important potential refuge that becomes accessible for discharges with a return period of approximately one year. Conversely, sediment deficit results in a homogeneous flow field with steadily increasing hydraulic forces for high flows and impaired lateral connectivity except for very large flood events of a 30- to 100-year return period. Dynamic river widening implemented in a channel with sediment equilibrium conditions as opposed to a sediment deficit is thus more likely to provide flood refugia.","PeriodicalId":93201,"journal":{"name":"Journal of ecohydraulics","volume":"33 1","pages":"121 - 138"},"PeriodicalIF":0.0,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84623649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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