Richard Sharpe, Andrew Brooks, Jon Olley, Justine Kemp
Riparian forests contribute to the resilience and biocomplexity of floodplains but may be catastrophically impacted by large floods. Forest disturbances will expose floodplains to stripping and pulses of large wood recruitment to the floodplain and channel. The widespread uprooting of trees follows hydrodynamic loading from floodwaters and the associated moments of these forces about the tree bases. A tree will uproot when the drag moment exceeds the anchorage resistance capacity. Alternatively, trunks will rupture when the tensile stresses caused by bending exceed the tensile strength of the outer trunk fibres. The likelihood and pattern of trees dislodging during floods on a subtropical river was investigated by developing a tree stability model. The modeling framework included development of a drag moment model and testing several potential formulations for anchorage resistance. Model parameters were calibrated to data collected in experiments and from observations in aerial photographs before and after a large flood in 2011. The prediction accuracy for the adopted tree stability model was 78%. Results from design flood simulations suggest that less than a third of the forest will dislodge even during the largest floods conceivable. This remarkable stability moderates the quantity of large wood recruited from riparian forests during extreme floods, which can impact infrastructure such as bridges and culverts downstream. Low rates of wood recruitment from dislodged floodplain trees in extreme floods suggests bank erosion is the dominant source of wood recruitment in these catchments.
{"title":"Patterns of riparian forest disturbance caused by tree dislodging on a subtropical river during large floods","authors":"Richard Sharpe, Andrew Brooks, Jon Olley, Justine Kemp","doi":"10.1002/rra.4298","DOIUrl":"https://doi.org/10.1002/rra.4298","url":null,"abstract":"Riparian forests contribute to the resilience and biocomplexity of floodplains but may be catastrophically impacted by large floods. Forest disturbances will expose floodplains to stripping and pulses of large wood recruitment to the floodplain and channel. The widespread uprooting of trees follows hydrodynamic loading from floodwaters and the associated moments of these forces about the tree bases. A tree will uproot when the drag moment exceeds the anchorage resistance capacity. Alternatively, trunks will rupture when the tensile stresses caused by bending exceed the tensile strength of the outer trunk fibres. The likelihood and pattern of trees dislodging during floods on a subtropical river was investigated by developing a tree stability model. The modeling framework included development of a drag moment model and testing several potential formulations for anchorage resistance. Model parameters were calibrated to data collected in experiments and from observations in aerial photographs before and after a large flood in 2011. The prediction accuracy for the adopted tree stability model was 78%. Results from design flood simulations suggest that less than a third of the forest will dislodge even during the largest floods conceivable. This remarkable stability moderates the quantity of large wood recruited from riparian forests during extreme floods, which can impact infrastructure such as bridges and culverts downstream. Low rates of wood recruitment from dislodged floodplain trees in extreme floods suggests bank erosion is the dominant source of wood recruitment in these catchments.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140941228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hydropeaking is one of the most severe pressures of hydropower on aquatic ecosystems. The discharge fluctuations due to turbine operations cause frequent shifts in hydraulic habitat characteristics such as flow velocity and water depth. Those rapid changes on a daily or sub daily basis, however, are beyond the possibilities of evolutionary adaptations of aquatic organisms, especially for fish in their sensitive early life stages. Thus, one central aim in terms of the evaluation of hydropeaking impacts or the design of mitigation measures is the analysis or establishment of hydraulically stable habitat conditions. This study presents a novel habitat assessment tool to quantify hydraulically stable habitat conditions in the form of a persistency of suitable habitats in hydropeaking reaches. The HEM‐PEAK tool determines areas that contain equal ranges of depth‐averaged flow velocity and water depth for both base flow and peak flow in three categories. Those areas also exclude dewatering sites, which have to be seen as ‘residual risk for stranding’. In the present study, the model was used to evaluate the YOY habitats of brown trout and grayling. The model was tested for 14 hydropeaking reaches to evaluate the quantity of habitat persistency for different morphological characteristics, such as straight, winding, alternating gravel bars and bifurcation reaches. The findings reveal that there is no relationship between hydraulically stable habitat conditions with reach scale bed slope or the magnitude of dewatering areas. However, the changes in specific discharge in relation to bankfull width could be negatively related to the magnitude of hydraulically stable habitat conditions independent of the morphological type. This relationship is minor for summer scenarios compared to spring, as the initial habitat quality during the increased base flow conditions is already limiting the availability of suitable habitats which might have persistency during peak flow. In detail, several self‐forming bars like point bars and artificial structures like groins and coarse rip‐rap could be determined, which could be explicitly addressed in terms of mitigation measure design based on the application of the HEM‐PEAK tool.
{"title":"Habitat persistency analysis with HEM‐PEAK: A novel approach for the assessment of hydropeaking impacts and mitigation measure design","authors":"C. Hauer, G. Unfer, P. Holzapfel, M. Tritthart","doi":"10.1002/rra.4291","DOIUrl":"https://doi.org/10.1002/rra.4291","url":null,"abstract":"Hydropeaking is one of the most severe pressures of hydropower on aquatic ecosystems. The discharge fluctuations due to turbine operations cause frequent shifts in hydraulic habitat characteristics such as flow velocity and water depth. Those rapid changes on a daily or sub daily basis, however, are beyond the possibilities of evolutionary adaptations of aquatic organisms, especially for fish in their sensitive early life stages. Thus, one central aim in terms of the evaluation of hydropeaking impacts or the design of mitigation measures is the analysis or establishment of hydraulically stable habitat conditions. This study presents a novel habitat assessment tool to quantify hydraulically stable habitat conditions in the form of a persistency of suitable habitats in hydropeaking reaches. The HEM‐PEAK tool determines areas that contain equal ranges of depth‐averaged flow velocity and water depth for both base flow and peak flow in three categories. Those areas also exclude dewatering sites, which have to be seen as ‘residual risk for stranding’. In the present study, the model was used to evaluate the YOY habitats of brown trout and grayling. The model was tested for 14 hydropeaking reaches to evaluate the quantity of habitat persistency for different morphological characteristics, such as straight, winding, alternating gravel bars and bifurcation reaches. The findings reveal that there is no relationship between hydraulically stable habitat conditions with reach scale bed slope or the magnitude of dewatering areas. However, the changes in specific discharge in relation to bankfull width could be negatively related to the magnitude of hydraulically stable habitat conditions independent of the morphological type. This relationship is minor for summer scenarios compared to spring, as the initial habitat quality during the increased base flow conditions is already limiting the availability of suitable habitats which might have persistency during peak flow. In detail, several self‐forming bars like point bars and artificial structures like groins and coarse rip‐rap could be determined, which could be explicitly addressed in terms of mitigation measure design based on the application of the HEM‐PEAK tool.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140941299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The presence of dams on the Columbia River (CR) has reduced Sockeye Salmon (Oncorhynchus nerka|sćwin) numbers to a fraction of their historic numbers. The Syilx Okanagan Nation Alliance (SONA) has led voices of concern regarding the impacts of diminishing Sockeye Salmon numbers on the ecosystem health of the sawsitkʷ|Okanagan River (s|OR), a tributary of the CR. In the early 2000s efforts commenced to rehabilitate the s|OR Sockeye population. These efforts have seen the population rise from a running average of 40,000 to 200,000. However, the contemporary spawning capacity of the s|OR is unknown, and this metric is critical to guide the conservation and restoration of this keystone species. We employed a spawning capacity model relating fish length and gravel size to spawning potential. We collected substrate data at 49 sites throughout our 37‐km study area, and used fish length and egg numbers from n = 269 Sockeye Salmon to establish s|OR specific fecundity metrics. The model estimated the s|OR has the capacity to support 147,687 (±33,346) Sockeye spawners, in its current condition. Whilst our model has limitations, we suggest a minimum escapement of 147,687 Sockeye spawners ought to be passed to the s|OR per annum. These fish will have broad ecosystem benefits and will be culturally beneficial to SONA peoples. Finally, continued restoration of s|OR habitat should enhance opportunities for Sockeye Salmon to continue their remarkable recovery.
{"title":"Establishing present‐day Sockeye Salmon (Oncorhynchus nerka|sćwin) spawning capacity in the highly impacted sq,awsitkʷ|Okanagan River to guide population conservation and restoration","authors":"Antóin M. O'Sullivan, Karilyn I. Alex","doi":"10.1002/rra.4293","DOIUrl":"https://doi.org/10.1002/rra.4293","url":null,"abstract":"The presence of dams on the Columbia River (CR) has reduced Sockeye Salmon (<jats:italic>Oncorhynchus nerka|sćwin</jats:italic>) numbers to a fraction of their historic numbers. The Syilx Okanagan Nation Alliance (SONA) has led voices of concern regarding the impacts of diminishing Sockeye Salmon numbers on the ecosystem health of the sawsitkʷ|Okanagan River (s|OR), a tributary of the CR. In the early 2000s efforts commenced to rehabilitate the s|OR Sockeye population. These efforts have seen the population rise from a running average of 40,000 to 200,000. However, the contemporary spawning capacity of the s|OR is unknown, and this metric is critical to guide the conservation and restoration of this keystone species. We employed a spawning capacity model relating fish length and gravel size to spawning potential. We collected substrate data at 49 sites throughout our 37‐km study area, and used fish length and egg numbers from <jats:italic>n</jats:italic> = 269 Sockeye Salmon to establish s|OR specific fecundity metrics. The model estimated the s|OR has the capacity to support 147,687 (±33,346) Sockeye spawners, in its current condition. Whilst our model has limitations, we suggest a minimum escapement of 147,687 Sockeye spawners ought to be passed to the s|OR per annum. These fish will have broad ecosystem benefits and will be culturally beneficial to SONA peoples. Finally, continued restoration of s|OR habitat should enhance opportunities for Sockeye Salmon to continue their remarkable recovery.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140941516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Laura E. Rack, Mary C. Freeman, Ben N. Emanuel, Laura S. Craig, Stephen W. Golladay, Carol Yang, Seth J. Wenger
Managing aquatic ecosystems for people and nature can be improved by collaboration among scientists, managers, decision‐makers, and other stakeholders. Many collaborative and interdisciplinary approaches have been developed to address the management of freshwater ecosystems; however, there are still barriers to overcome. We worked as part of a regional stakeholder group comprising municipal water utility operators, conservation organizations, academic partners, and other stakeholders to understand the effects of low‐flow and drought on ecological functions of the upper Flint River, Georgia (USA), a free‐flowing river important for municipal water supply, recreation, and native biota. We used published literature and locally targeted studies to identify quantitative flow targets that could be used to inform water management and drought planning. Drawing from principles of Translational Ecology, we relied on an iterative process to develop information needs for the group and maintained communication and engagement throughout data collection, analysis, and synthesis. We identified three quantitative flow benchmarks to evaluate the ecological impacts of drought in the river. The results were valuable to both the water utilities represented in the working group and State regional water planning, which is used to guide water management strategies and permitting for the basin. We identified principles that were important for the successful engagement in the working group and helped to overcome the challenge of working across sectors and without direct authority guiding the implementation of our work. Interdisciplinary work and creative solutions are crucial to plan for and adapt to greater pressure on our water resources.
{"title":"How low is too low? Partnering with stakeholders and managers to define ecologically based low‐flow thresholds in a perennial temperate river","authors":"Laura E. Rack, Mary C. Freeman, Ben N. Emanuel, Laura S. Craig, Stephen W. Golladay, Carol Yang, Seth J. Wenger","doi":"10.1002/rra.4301","DOIUrl":"https://doi.org/10.1002/rra.4301","url":null,"abstract":"Managing aquatic ecosystems for people and nature can be improved by collaboration among scientists, managers, decision‐makers, and other stakeholders. Many collaborative and interdisciplinary approaches have been developed to address the management of freshwater ecosystems; however, there are still barriers to overcome. We worked as part of a regional stakeholder group comprising municipal water utility operators, conservation organizations, academic partners, and other stakeholders to understand the effects of low‐flow and drought on ecological functions of the upper Flint River, Georgia (USA), a free‐flowing river important for municipal water supply, recreation, and native biota. We used published literature and locally targeted studies to identify quantitative flow targets that could be used to inform water management and drought planning. Drawing from principles of Translational Ecology, we relied on an iterative process to develop information needs for the group and maintained communication and engagement throughout data collection, analysis, and synthesis. We identified three quantitative flow benchmarks to evaluate the ecological impacts of drought in the river. The results were valuable to both the water utilities represented in the working group and State regional water planning, which is used to guide water management strategies and permitting for the basin. We identified principles that were important for the successful engagement in the working group and helped to overcome the challenge of working across sectors and without direct authority guiding the implementation of our work. Interdisciplinary work and creative solutions are crucial to plan for and adapt to greater pressure on our water resources.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140941303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Stanley Gregory, Linda Ashkenas, Randall Wildman, George Lienkaemper, Ivan Arismendi, Gary A. Lamberti, Mark Meleason, Brooke E. Penaluna, Daniel Sobota
We quantified temporal dynamics of wood storage, input, and transport over a 24‐year period in adjacent old‐growth and second‐growth forested reaches in Mack Creek, a third‐order stream in the Cascade Range of Oregon. The standing stocks of large wood in the old‐growth reach exceeded those at the second‐growth reach by more than double the number of wood pieces and triple the wood volume. Annual inputs of large wood were highly variable. Wood numbers delivered into the old‐growth reach were 3× higher and wood volume 10× greater than in the second‐growth reach. The movement of number and volume of logs did not differ significantly between the two reaches over time. Less than 2% of the logs moved in most years, and the highest proportion moved in the year of the 1996 flood (9% in old growth and 22% in second growth). Most of the large wood aggregated as jams in both reaches. The second‐growth reach lacked major jams, but 29% of the logs in the old growth were in full‐channel spanning jams. Long‐term observations of annual storage, input, and movement reveal the temporal dynamics of wood rather than static representations of the characteristics of wood. Input events and transport of wood in Mack Creek were episodic and varied greatly over the 24‐year study, which illustrates one of the major challenges and opportunities for understanding the cumulative dynamics of wood in streams.
{"title":"Long‐term dynamics of large wood in old‐growth and second‐growth stream reaches in the Cascade Range of Oregon","authors":"Stanley Gregory, Linda Ashkenas, Randall Wildman, George Lienkaemper, Ivan Arismendi, Gary A. Lamberti, Mark Meleason, Brooke E. Penaluna, Daniel Sobota","doi":"10.1002/rra.4294","DOIUrl":"https://doi.org/10.1002/rra.4294","url":null,"abstract":"We quantified temporal dynamics of wood storage, input, and transport over a 24‐year period in adjacent old‐growth and second‐growth forested reaches in Mack Creek, a third‐order stream in the Cascade Range of Oregon. The standing stocks of large wood in the old‐growth reach exceeded those at the second‐growth reach by more than double the number of wood pieces and triple the wood volume. Annual inputs of large wood were highly variable. Wood numbers delivered into the old‐growth reach were 3× higher and wood volume 10× greater than in the second‐growth reach. The movement of number and volume of logs did not differ significantly between the two reaches over time. Less than 2% of the logs moved in most years, and the highest proportion moved in the year of the 1996 flood (9% in old growth and 22% in second growth). Most of the large wood aggregated as jams in both reaches. The second‐growth reach lacked major jams, but 29% of the logs in the old growth were in full‐channel spanning jams. Long‐term observations of annual storage, input, and movement reveal the temporal dynamics of wood rather than static representations of the characteristics of wood. Input events and transport of wood in Mack Creek were episodic and varied greatly over the 24‐year study, which illustrates one of the major challenges and opportunities for understanding the cumulative dynamics of wood in streams.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140941234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Étienne Gariépy‐Girouard, Thomas Buffin‐Bélanger, Pascale M. Biron
Integrating hydrogeomorphological (HGM) principles into the restoration of degraded rivers can achieve sustainable results and provide various human benefits. HGM principles mainly involve understanding the context and processes that shape a fluvial system before any intervention, in order to support its dynamism and to align with its potential functioning and uses. Despite recent management approaches inspired by HGM principles, most restoration projects carried out in Quebec (Canada) are not process‐based and target specific one‐dimensional objectives. Although there is an overall lack of post‐project monitoring, several projects appear to have failed or had mixed success. This research aims to shed light on the diversity of societal drivers behind river restoration projects and to examine how they influence the integration of HGM principles and human benefits. Four restoration projects were characterized through participant observation and interviews with the organizations running them. Representatives of two ministries involved in river restoration and management were also interviewed. The results show that projects were mainly shaped by public acceptance disregarding HGM principles, which can lead to poorly‐informed action. Project funding and stakeholders' expertise have also challenged project implementation and played a key role in defining their objectives. The addition of these components improve the current analytical frameworks for identifying river restoration objectives. Depending on specific sociocultural, political and legislative contexts, funding programs and stakeholders' expertise may either facilitate or restrict the integration of HGM principles and human benefits in the projects. Recognizing these key drivers reframes river restoration as a fundamentally social activity and enlightens how they could impel innovative approaches towards more sustainable results.
{"title":"Societal drivers for the integration of hydrogeomorphology and human benefits in river restoration projects","authors":"Étienne Gariépy‐Girouard, Thomas Buffin‐Bélanger, Pascale M. Biron","doi":"10.1002/rra.4304","DOIUrl":"https://doi.org/10.1002/rra.4304","url":null,"abstract":"Integrating hydrogeomorphological (HGM) principles into the restoration of degraded rivers can achieve sustainable results and provide various human benefits. HGM principles mainly involve understanding the context and processes that shape a fluvial system before any intervention, in order to support its dynamism and to align with its potential functioning and uses. Despite recent management approaches inspired by HGM principles, most restoration projects carried out in Quebec (Canada) are not process‐based and target specific one‐dimensional objectives. Although there is an overall lack of post‐project monitoring, several projects appear to have failed or had mixed success. This research aims to shed light on the diversity of societal drivers behind river restoration projects and to examine how they influence the integration of HGM principles and human benefits. Four restoration projects were characterized through participant observation and interviews with the organizations running them. Representatives of two ministries involved in river restoration and management were also interviewed. The results show that projects were mainly shaped by public acceptance disregarding HGM principles, which can lead to poorly‐informed action. Project funding and stakeholders' expertise have also challenged project implementation and played a key role in defining their objectives. The addition of these components improve the current analytical frameworks for identifying river restoration objectives. Depending on specific sociocultural, political and legislative contexts, funding programs and stakeholders' expertise may either facilitate or restrict the integration of HGM principles and human benefits in the projects. Recognizing these key drivers reframes river restoration as a fundamentally social activity and enlightens how they could impel innovative approaches towards more sustainable results.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140941499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kristin Peters, Sven F. Grantz, Jens Kiesel, Jörg Lewandowski, Nicola Fohrer
Elevated stream temperatures under low‐flows, exacerbated by global warming, are a stressor that affects aquatic species directly or in combination with other stressors. Stream temperatures are influenced by energy fluxes across the air–water interface as well as by hydrological exchange processes occurring at the water–riverbed interface. Small‐scale stream temperature dynamics influenced by exchange flows are still underrepresented in stream temperature research. To investigate high‐resolution temperature dynamics and hydrological exchange processes at the sediment–water interface we applied fiber‐optic distributed temperature sensing (FO‐DTS) at two sites in the mountainous Kinzig catchment combined with mapping and measurement of additional environmental conditions. Two types of temperature anomalies could be observed at one site under conditions of low flow and high air temperature. Dampening effects coincided with riverine features such as pools, vegetation roots, fine sediment, and signs of streambank seepage which indicated hyporheic exchange flows. Increased heating of the substrate during the day was identified in shallow sections where sediment was exposed to the air and shading from riparian vegetation was patchy. At another site, at which the cable could not be buried because of the sediment composition, temperature anomalies in the overlying water indicated diffuse groundwater exfiltration. The results show that small‐scale processes in the hyporheic zone, low water tables, and riparian shading influence stream temperature in mountainous streams and can be identified with FO‐DTS under suitable conditions. The results improve our understanding of stream temperatures (in the hyporheic zone) and provide important information on how to improve hydrological modeling.
{"title":"Hyporheic exchange flows in a mountainous river catchment identified by distributed temperature sensing","authors":"Kristin Peters, Sven F. Grantz, Jens Kiesel, Jörg Lewandowski, Nicola Fohrer","doi":"10.1002/rra.4306","DOIUrl":"https://doi.org/10.1002/rra.4306","url":null,"abstract":"Elevated stream temperatures under low‐flows, exacerbated by global warming, are a stressor that affects aquatic species directly or in combination with other stressors. Stream temperatures are influenced by energy fluxes across the air–water interface as well as by hydrological exchange processes occurring at the water–riverbed interface. Small‐scale stream temperature dynamics influenced by exchange flows are still underrepresented in stream temperature research. To investigate high‐resolution temperature dynamics and hydrological exchange processes at the sediment–water interface we applied fiber‐optic distributed temperature sensing (FO‐DTS) at two sites in the mountainous Kinzig catchment combined with mapping and measurement of additional environmental conditions. Two types of temperature anomalies could be observed at one site under conditions of low flow and high air temperature. Dampening effects coincided with riverine features such as pools, vegetation roots, fine sediment, and signs of streambank seepage which indicated hyporheic exchange flows. Increased heating of the substrate during the day was identified in shallow sections where sediment was exposed to the air and shading from riparian vegetation was patchy. At another site, at which the cable could not be buried because of the sediment composition, temperature anomalies in the overlying water indicated diffuse groundwater exfiltration. The results show that small‐scale processes in the hyporheic zone, low water tables, and riparian shading influence stream temperature in mountainous streams and can be identified with FO‐DTS under suitable conditions. The results improve our understanding of stream temperatures (in the hyporheic zone) and provide important information on how to improve hydrological modeling.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140941294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Stewart B. Rood, Gregory C. Hoffman, Norm Merz, Paul Anders, Rohan Benjankar, Michael Burke, Gregory Egger, Mary Louise Polzin, Scott Soults
The cover image is based on the Research Article Collateral benefits: River flow normalization for endangered fish enabled riparian rejuvenation by Stewart B. Rood et al., https://doi.org/10.1002/rra.4255.image
封面图片基于研究文章《附带利益》：为濒危鱼类实现河流流量正常化，使河岸恢复活力，Stewart B. Rood 等著，https://doi.org/10.1002/rra.4255.image
{"title":"Featured Cover","authors":"Stewart B. Rood, Gregory C. Hoffman, Norm Merz, Paul Anders, Rohan Benjankar, Michael Burke, Gregory Egger, Mary Louise Polzin, Scott Soults","doi":"10.1002/rra.4308","DOIUrl":"https://doi.org/10.1002/rra.4308","url":null,"abstract":"The cover image is based on the Research Article <jats:italic>Collateral benefits: River flow normalization for endangered fish enabled riparian rejuvenation</jats:italic> by Stewart B. Rood et al., <jats:ext-link xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"https://doi.org/10.1002/rra.4255\">https://doi.org/10.1002/rra.4255</jats:ext-link>.<jats:boxed-text content-type=\"graphic\" position=\"anchor\"><jats:graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mimetype=\"image/png\" position=\"anchor\" specific-use=\"enlarged-web-image\" xlink:href=\"graphic/rra4308-gra-0001-m.png\"><jats:alt-text>image</jats:alt-text></jats:graphic></jats:boxed-text>","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140941231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Tooth, A. Keen‐Zebert, M. C. Grenfell, G. Addison
Previous research on mixed bedrock‐alluvial anabranching rivers has documented how alluvial islands commonly grow under vegetation influences atop slowly eroding bedrock templates, but timescales of island dynamics remain poorly constrained. We focus on the Vaal River near Parys, South Africa, and combine field investigations, aerial image analyses and optically stimulated luminescence (OSL) dating to establish timescales of initiation, growth and erosion for nine bedrock‐cored, tree‐covered, alluvial islands. For each island, two OSL samples were collected in vertical succession from sand‐rich exposures up to 4 m in thickness to establish minimum ages for island initiation (~1802 to 243 years) and to estimate local vertical aggradation rates (~0.20 to 1.8 cm year−1). The diachronous lower ages and lack of systematic upstream‐downstream trend in island age support an interpretation of patchwork initiation, growth, and erosion of islands throughout the late Holocene. Following island initiation, vertical island aggradation occurs in association with establishment of reeds, shrubs and trees, but erosion of island margins or dissection by cross‐cutting channels also can occur. Observations during and after recent large floods (peak discharges >3000 m3 s−1) provide further insights into island dynamics, including the influence of exotic trees (e.g., Eucalyptus spp.) that have colonised many islands in the postcolonial era (last ~150 years). Our findings extend previous conceptual models by constraining timescales of island dynamics and providing new insights into island stability and longevity in mixed bedrock‐alluvial anabranching rivers. Improved communication of findings regarding island geomorphology, ecology and stability can benefit local community engagement, geo/eco‐tourism and education activities, and land use planning.
{"title":"Timescales of tree‐covered island dynamics on the mixed bedrock‐alluvial anabranching Vaal River, South Africa","authors":"S. Tooth, A. Keen‐Zebert, M. C. Grenfell, G. Addison","doi":"10.1002/rra.4296","DOIUrl":"https://doi.org/10.1002/rra.4296","url":null,"abstract":"Previous research on mixed bedrock‐alluvial anabranching rivers has documented how alluvial islands commonly grow under vegetation influences atop slowly eroding bedrock templates, but timescales of island dynamics remain poorly constrained. We focus on the Vaal River near Parys, South Africa, and combine field investigations, aerial image analyses and optically stimulated luminescence (OSL) dating to establish timescales of initiation, growth and erosion for nine bedrock‐cored, tree‐covered, alluvial islands. For each island, two OSL samples were collected in vertical succession from sand‐rich exposures up to 4 m in thickness to establish minimum ages for island initiation (~1802 to 243 years) and to estimate local vertical aggradation rates (~0.20 to 1.8 cm year<jats:sup>−1</jats:sup>). The diachronous lower ages and lack of systematic upstream‐downstream trend in island age support an interpretation of patchwork initiation, growth, and erosion of islands throughout the late Holocene. Following island initiation, vertical island aggradation occurs in association with establishment of reeds, shrubs and trees, but erosion of island margins or dissection by cross‐cutting channels also can occur. Observations during and after recent large floods (peak discharges >3000 m<jats:sup>3</jats:sup> s<jats:sup>−1</jats:sup>) provide further insights into island dynamics, including the influence of exotic trees (e.g., <jats:italic>Eucalyptus</jats:italic> spp.) that have colonised many islands in the postcolonial era (last ~150 years). Our findings extend previous conceptual models by constraining timescales of island dynamics and providing new insights into island stability and longevity in mixed bedrock‐alluvial anabranching rivers. Improved communication of findings regarding island geomorphology, ecology and stability can benefit local community engagement, geo/eco‐tourism and education activities, and land use planning.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140941297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rossa O'Briain, Dov Corenblit, Virginia Garófano‐Gómez, Ciara O'Leary
The current focus of river restoration on flow and sediment transfer without proper consideration of vegetation as a key structuring agent, beyond its stabilising effect, is too simplistic. We contend that vegetation has an essential role in shaping the physical fluvial environment and should be considered equally alongside hydrogeomorphic processes in restoration projects. In support, we introduce engineer plants as important controls, along with flowing water and transported sediments, on the morphodynamics of river systems and associated physical habitat development. The effect of vegetation on channel planform is then summarised, the influence of vegetation on hydrogeomorphic connectivity is outlined, and then the role of vegetation in landform development and habitat provision, as encapsulated in the fluvial biogeomorphic succession model, is described. We then present examples demonstrating how vegetation has contributed to the recovery of degraded rivers through biogeomorphic processes. Finally, we advance the concept of biogeomorphic river restoration by proposing principles to support a closer synthesis of the component sciences and list key areas for practitioners to focus on. Vegetation succession has a significance that goes beyond its physical structure or influence on sediment stability. In many river settings, it is central to channel evolution. The coupled assembly of plant communities and fluvial landforms affect the development of spatially and temporally dynamic habitat through biogeomorphic interactions. Restoration approaches that do not fully consider this dynamic may fail to anticipate river behaviour and recovery trajectories.
{"title":"Towards biogeomorphic river restoration: Vegetation as a critical driver of physical habitat","authors":"Rossa O'Briain, Dov Corenblit, Virginia Garófano‐Gómez, Ciara O'Leary","doi":"10.1002/rra.4288","DOIUrl":"https://doi.org/10.1002/rra.4288","url":null,"abstract":"The current focus of river restoration on flow and sediment transfer without proper consideration of vegetation as a key structuring agent, beyond its stabilising effect, is too simplistic. We contend that vegetation has an essential role in shaping the physical fluvial environment and should be considered equally alongside hydrogeomorphic processes in restoration projects. In support, we introduce engineer plants as important controls, along with flowing water and transported sediments, on the morphodynamics of river systems and associated physical habitat development. The effect of vegetation on channel planform is then summarised, the influence of vegetation on hydrogeomorphic connectivity is outlined, and then the role of vegetation in landform development and habitat provision, as encapsulated in the fluvial biogeomorphic succession model, is described. We then present examples demonstrating how vegetation has contributed to the recovery of degraded rivers through biogeomorphic processes. Finally, we advance the concept of biogeomorphic river restoration by proposing principles to support a closer synthesis of the component sciences and list key areas for practitioners to focus on. Vegetation succession has a significance that goes beyond its physical structure or influence on sediment stability. In many river settings, it is central to channel evolution. The coupled assembly of plant communities and fluvial landforms affect the development of spatially and temporally dynamic habitat through biogeomorphic interactions. Restoration approaches that do not fully consider this dynamic may fail to anticipate river behaviour and recovery trajectories.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140887679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：