Brian W. Hodge, Richard Henderson, Christopher E. Brehme
Restoration practitioners spend more than $1 billion each year restoring US rivers and streams but commit comparatively few resources to evaluating project effectiveness. Meanwhile, monitoring and disseminating the outcomes of restoration projects remains our best opportunity to learn from past successes and failures and to, ultimately, improve the cost effectiveness of restoration. We monitored the physical and biological outcomes of a stream restoration project in the Rocky Mountains, the goals of which were to improve habitat for and productivity of native Colorado River Cutthroat Trout (CRCT) and the scope of which included three contiguous reaches under different restoration treatments. Moreover, we evaluated the efficacy of the restoration project relative to its stated goals and objectives. To test for restoration effects on physical and biological indicators we coupled a before‐after, control‐impact (BACI) study design with (generalized) linear mixed models. Over the course of 7 years, we detected restoration‐related increases in floodplain connectivity, streambank stability, and riparian shrub cover, as well as decreases in summer stream temperature. Despite measured improvements in native trout habitat, we detected no evidence of a restoration effect on density or biomass of age‐1 and older CRCT. Although our study was somewhat limited in scope, our findings contribute toward a relatively small body of work on monitoring and effectiveness of river restoration.
{"title":"Stream Restoration Effects on Habitat and Abundance of Native Cutthroat Trout","authors":"Brian W. Hodge, Richard Henderson, Christopher E. Brehme","doi":"10.1002/rra.4373","DOIUrl":"https://doi.org/10.1002/rra.4373","url":null,"abstract":"Restoration practitioners spend more than $1 billion each year restoring US rivers and streams but commit comparatively few resources to evaluating project effectiveness. Meanwhile, monitoring and disseminating the outcomes of restoration projects remains our best opportunity to learn from past successes and failures and to, ultimately, improve the cost effectiveness of restoration. We monitored the physical and biological outcomes of a stream restoration project in the Rocky Mountains, the goals of which were to improve habitat for and productivity of native Colorado River Cutthroat Trout (CRCT) and the scope of which included three contiguous reaches under different restoration treatments. Moreover, we evaluated the efficacy of the restoration project relative to its stated goals and objectives. To test for restoration effects on physical and biological indicators we coupled a before‐after, control‐impact (BACI) study design with (generalized) linear mixed models. Over the course of 7 years, we detected restoration‐related increases in floodplain connectivity, streambank stability, and riparian shrub cover, as well as decreases in summer stream temperature. Despite measured improvements in native trout habitat, we detected no evidence of a restoration effect on density or biomass of age‐1 and older CRCT. Although our study was somewhat limited in scope, our findings contribute toward a relatively small body of work on monitoring and effectiveness of river restoration.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185765","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}
M. R. Fuller, N. E. Detenbeck, P. Leinenbach, R. Labiosa, D. Isaak
Under the United States Clean Water Act, states are required to periodically assess state waters to determine compliance with water quality criteria (including temperature) and then to develop total maximum daily loads (TMDLs) for impaired waters as necessary to bring them into compliance. We compared the performance of mechanistic stream temperature models (HeatSource, QUAL2K, and QUAL2Kw) applied to the mainstem of three TMDL watersheds (Middle Fork John Day, OR; Wind River, WA; South Fork Nooksack, WA) with that of spatial stream network (SSN) models applied to the full watersheds and used these to evaluate the potential effectiveness of restoration strategies. SSN models performed well with slightly lesser accuracy (RMSE = 0.47–0.87) for mainstem predictions than mechanistic models (RMSE = 0.4) but provided additional benefits to inform management, including information on spatial and temporal heterogeneity of restoration effectiveness throughout the watershed. Of the four scenarios considered (restoration of riparian zones to potential natural vegetation, channel narrowing, increasing flow by restricting irrigation withdrawals, and combined applications), riparian zone restoration was consistently the most effective in reducing temperatures at the outlet, mainstem, and throughout the watersheds. Predicted restoration effectiveness for thermal regimes varied significantly both within and among watersheds. A focus on water quality criteria exceedance only at the watershed outlet or along the mainstem reach can obscure knowledge of restoration potential for fish habitat in tributaries and headwaters, potential for creation of thermal refuge areas along the mainstem critical for maintaining migration corridors, and thermal regime heterogeneity across space and time.
{"title":"Scenario Planning Management Actions to Restore Cold Water Stream Habitat: Comparing Mechanistic and Statistical Modeling Approaches","authors":"M. R. Fuller, N. E. Detenbeck, P. Leinenbach, R. Labiosa, D. Isaak","doi":"10.1002/rra.4381","DOIUrl":"https://doi.org/10.1002/rra.4381","url":null,"abstract":"Under the United States Clean Water Act, states are required to periodically assess state waters to determine compliance with water quality criteria (including temperature) and then to develop total maximum daily loads (TMDLs) for impaired waters as necessary to bring them into compliance. We compared the performance of mechanistic stream temperature models (HeatSource, QUAL2K, and QUAL2Kw) applied to the mainstem of three TMDL watersheds (Middle Fork John Day, OR; Wind River, WA; South Fork Nooksack, WA) with that of spatial stream network (SSN) models applied to the full watersheds and used these to evaluate the potential effectiveness of restoration strategies. SSN models performed well with slightly lesser accuracy (RMSE = 0.47–0.87) for mainstem predictions than mechanistic models (RMSE = 0.4) but provided additional benefits to inform management, including information on spatial and temporal heterogeneity of restoration effectiveness throughout the watershed. Of the four scenarios considered (restoration of riparian zones to potential natural vegetation, channel narrowing, increasing flow by restricting irrigation withdrawals, and combined applications), riparian zone restoration was consistently the most effective in reducing temperatures at the outlet, mainstem, and throughout the watersheds. Predicted restoration effectiveness for thermal regimes varied significantly both within and among watersheds. A focus on water quality criteria exceedance only at the watershed outlet or along the mainstem reach can obscure knowledge of restoration potential for fish habitat in tributaries and headwaters, potential for creation of thermal refuge areas along the mainstem critical for maintaining migration corridors, and thermal regime heterogeneity across space and time.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185732","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}
Humans have extensively altered rivers to accommodate anthropogenic uses. Dams modify river flow and temperature regimes important for lotic fish reproduction. Yet, assessments of fish production in relation to environmental conditions in regulated rivers are lacking but are needed to guide experimental environmental flows. We evaluated the effects of water temperature and discharge on larval Catostomidae, Sciaenidae, and Clupeidae production to inform environmental flow management. We sampled ichthyoplankton from April through June on the Des Moines and Iowa rivers prior to (2014–2015) and after (2021–2022) an experimental environmental flow was incorporated on the Des Moines River. We used a hurdle model to assess the effects of water temperature, discharge, and discharge variation on larval presence (logistic regression) and density (linear regression). Larval Catostomidae were captured once water temperatures exceeded 15°C, Sciaenidae appeared when water temperature surpassed 18°C, while Clupeidae appeared when water temperature exceeded 20°C. The probability of larval Sciaenidae and Clupeidae presence increased with discharge variation while densities were both positively associated with discharge and discharge variation. The probability of Sciaenidae and Catostomidae larval presence increased with water temperature. Interactions between water temperature and discharge influenced Clupeidae presence and Catostomidae density. The probability of Clupeidae presence increased with discharge at warmer water temperatures. Catostomidae densities increased with discharge at cool water temperature (13°C) and decreased with discharge at warm (25°C) temperatures. Our results provide information about the effects of discharge, discharge variation, and water temperature driving larval fish production in anthropogenically altered rivers to guide environmental flow management.
{"title":"Environmental Factors Associated With Fish Reproduction in Regulated Rivers","authors":"Erik M. Griffen, Michael J. Weber","doi":"10.1002/rra.4376","DOIUrl":"https://doi.org/10.1002/rra.4376","url":null,"abstract":"Humans have extensively altered rivers to accommodate anthropogenic uses. Dams modify river flow and temperature regimes important for lotic fish reproduction. Yet, assessments of fish production in relation to environmental conditions in regulated rivers are lacking but are needed to guide experimental environmental flows. We evaluated the effects of water temperature and discharge on larval Catostomidae, Sciaenidae, and Clupeidae production to inform environmental flow management. We sampled ichthyoplankton from April through June on the Des Moines and Iowa rivers prior to (2014–2015) and after (2021–2022) an experimental environmental flow was incorporated on the Des Moines River. We used a hurdle model to assess the effects of water temperature, discharge, and discharge variation on larval presence (logistic regression) and density (linear regression). Larval Catostomidae were captured once water temperatures exceeded 15°C, Sciaenidae appeared when water temperature surpassed 18°C, while Clupeidae appeared when water temperature exceeded 20°C. The probability of larval Sciaenidae and Clupeidae presence increased with discharge variation while densities were both positively associated with discharge and discharge variation. The probability of Sciaenidae and Catostomidae larval presence increased with water temperature. Interactions between water temperature and discharge influenced Clupeidae presence and Catostomidae density. The probability of Clupeidae presence increased with discharge at warmer water temperatures. Catostomidae densities increased with discharge at cool water temperature (13°C) and decreased with discharge at warm (25°C) temperatures. Our results provide information about the effects of discharge, discharge variation, and water temperature driving larval fish production in anthropogenically altered rivers to guide environmental flow management.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185764","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}
A three‐dimensional coupled hydrodynamic and sediment transport model was employed to simulate the suspended sediment transport at a section of the Danube River, in Hungary. The case study is characterised by a highly complex hydromorphological system due to the nearby tributary inflow, the high number of river regulation structures as well as the several side‐arms connected to the Danube mainstem. The numerical model is set up, parameterised and validated against thorough field data of flow velocities and sediment concentrations measured at different hydrological regimes. Through the selected case study, the paper introduces (i) why 3D description is necessary at a reach‐scale analysis of complex hydromorphological systems; (ii) what sort of field data is needed to parameterise and validate a hydrodynamic and sediment transport model considering the spatial inhomogeneity of the flow and sediment features and (iii) an example for a quantitative impact assessment of side‐arm revitalisation measures on the sedimentation processes, playing a crucial role in the quality of riverine habitats.
{"title":"Simulation‐Based Assessment of Fine Sediment Transport to Support River Restoration Measures","authors":"Flóra Pomázi, Sándor Baranya","doi":"10.1002/rra.4378","DOIUrl":"https://doi.org/10.1002/rra.4378","url":null,"abstract":"A three‐dimensional coupled hydrodynamic and sediment transport model was employed to simulate the suspended sediment transport at a section of the Danube River, in Hungary. The case study is characterised by a highly complex hydromorphological system due to the nearby tributary inflow, the high number of river regulation structures as well as the several side‐arms connected to the Danube mainstem. The numerical model is set up, parameterised and validated against thorough field data of flow velocities and sediment concentrations measured at different hydrological regimes. Through the selected case study, the paper introduces (i) why 3D description is necessary at a reach‐scale analysis of complex hydromorphological systems; (ii) what sort of field data is needed to parameterise and validate a hydrodynamic and sediment transport model considering the spatial inhomogeneity of the flow and sediment features and (iii) an example for a quantitative impact assessment of side‐arm revitalisation measures on the sedimentation processes, playing a crucial role in the quality of riverine habitats.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224413","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}
J. C. White, E. Seddon, M. J. Hill, K. L. Mathers, M. Bridger, D. M. Hannah, P. J. Wood
River restoration practices are being increasingly implemented to help offset the global degradation of freshwater ecosystems. The ecological success of such projects is typically determined via post‐project appraisals comparing restored conditions against specified baselines (e.g., pre‐project and/or non‐restored data), but such approaches can overlook broader ecosystem recovery patterns. Using freshwater macroinvertebrate communities, this study examined ecological responses to river restoration that are seldom assessed: (i) sub‐annual temporal trajectories and (ii) palaeoecological versus contemporary community comparisons. Palaeoecological samples contained assemblages that existed prior to major anthropogenic pressures, which were collected from a sinuous palaeochannel that was restored and reconnected during the study; after which contemporary macroinvertebrate samples were collected. The restored channel initially supported an impoverished community, but taxonomic richness and densities were comparable to non‐restored conditions after 13‐months. The freshwater shrimp (Gammarus pulex) and non‐native New Zealand mud snail (Potamopyrgus antipodarum) proliferated 7‐months post‐restoration, and follow‐up biomonitoring highlighted their dominance prevailed 5‐years later. Such evidence indicates how ecosystem dynamics in the aftermath of restoration can shape longer‐term recovery. Palaeoecological communities exhibited higher biodiversity and conservation values compared with contemporary samples. This highlights that escalating anthropogenic pressures since the mid‐20th Century degraded macroinvertebrate communities, notably constraining marginal‐dwelling and lentic specialists. With palaeochannel reconnections being widely applied worldwide, this study demonstrates the value in collecting palaeoecological data before restoration works to provide valuable baseline information. As the global anthropogenic footprint increasingly degrades suitable “reference” river environments, palaeoecological data can better characterize biodiversity losses and potentially provide target conditions informing effective restoration activities.
{"title":"Going to the archives: Combining palaeoecological and contemporary data to support river restoration appraisals","authors":"J. C. White, E. Seddon, M. J. Hill, K. L. Mathers, M. Bridger, D. M. Hannah, P. J. Wood","doi":"10.1002/rra.4366","DOIUrl":"https://doi.org/10.1002/rra.4366","url":null,"abstract":"River restoration practices are being increasingly implemented to help offset the global degradation of freshwater ecosystems. The ecological success of such projects is typically determined via post‐project appraisals comparing restored conditions against specified baselines (e.g., pre‐project and/or non‐restored data), but such approaches can overlook broader ecosystem recovery patterns. Using freshwater macroinvertebrate communities, this study examined ecological responses to river restoration that are seldom assessed: (i) sub‐annual temporal trajectories and (ii) palaeoecological versus contemporary community comparisons. Palaeoecological samples contained assemblages that existed prior to major anthropogenic pressures, which were collected from a sinuous palaeochannel that was restored and reconnected during the study; after which contemporary macroinvertebrate samples were collected. The restored channel initially supported an impoverished community, but taxonomic richness and densities were comparable to non‐restored conditions after 13‐months. The freshwater shrimp (<jats:italic>Gammarus pulex</jats:italic>) and non‐native New Zealand mud snail (<jats:italic>Potamopyrgus antipodarum</jats:italic>) proliferated 7‐months post‐restoration, and follow‐up biomonitoring highlighted their dominance prevailed 5‐years later. Such evidence indicates how ecosystem dynamics in the aftermath of restoration can shape longer‐term recovery. Palaeoecological communities exhibited higher biodiversity and conservation values compared with contemporary samples. This highlights that escalating anthropogenic pressures since the mid‐20th Century degraded macroinvertebrate communities, notably constraining marginal‐dwelling and lentic specialists. With palaeochannel reconnections being widely applied worldwide, this study demonstrates the value in collecting palaeoecological data before restoration works to provide valuable baseline information. As the global anthropogenic footprint increasingly degrades suitable “reference” river environments, palaeoecological data can better characterize biodiversity losses and potentially provide target conditions informing effective restoration activities.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185810","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}
J. England, J. C. White, T. Johns, G. Meadows, D. M. Hannah
Physical habitat modification is one of the main pressures affecting river environments, impacting their ecosystem health and compromising their ability to adapt to the effects of climate change. Addressing the impacts of physical modification through reinvigorating natural processes has become a globally established river restoration technique. Here, we appraised such an approach by assessing ecological responses to a weir removal project on an English groundwater‐dominated ‘chalk’ stream. Using a Before‐After‐Control‐Impact (BACI) approach, we found that 3 years post‐restoration the macroinvertebrate communities are moving towards those of the target community both in terms of structural complexity (e.g., taxonomic composition) and functional integrity (e.g., trait composition). The progress is ongoing and has occurred alongside wider catchment improvements. Our results indicate that ecological responses to passive restoration undertaken on low energy streams, such as chalk streams, may be gradual, and thus longer‐term assessment is needed to fully appraise ecological recovery. We highlight the importance of a BACI approach to understand the local responses to restoration in a catchment context. Our findings also provide further evidence highlighting complementary ecological information provided by assessing taxonomic and functional properties concurrently in post‐project appraisals. A better understanding of ecological recovery times should be incorporated into future restoration planning. Such evidence would help develop robust assessments over appropriate timescales, increasing the likelihood of accurately and effectively appraising restoration project success, and helping to build support to increase the scale and pace of restoration actions needed to address biodiversity loss.
{"title":"Initial ecological recovery post‐weir removal amidst catchment‐wide improvements, in a groundwater‐dominated chalk stream","authors":"J. England, J. C. White, T. Johns, G. Meadows, D. M. Hannah","doi":"10.1002/rra.4351","DOIUrl":"https://doi.org/10.1002/rra.4351","url":null,"abstract":"Physical habitat modification is one of the main pressures affecting river environments, impacting their ecosystem health and compromising their ability to adapt to the effects of climate change. Addressing the impacts of physical modification through reinvigorating natural processes has become a globally established river restoration technique. Here, we appraised such an approach by assessing ecological responses to a weir removal project on an English groundwater‐dominated ‘chalk’ stream. Using a Before‐After‐Control‐Impact (BACI) approach, we found that 3 years post‐restoration the macroinvertebrate communities are moving towards those of the target community both in terms of structural complexity (e.g., taxonomic composition) and functional integrity (e.g., trait composition). The progress is ongoing and has occurred alongside wider catchment improvements. Our results indicate that ecological responses to passive restoration undertaken on low energy streams, such as chalk streams, may be gradual, and thus longer‐term assessment is needed to fully appraise ecological recovery. We highlight the importance of a BACI approach to understand the local responses to restoration in a catchment context. Our findings also provide further evidence highlighting complementary ecological information provided by assessing taxonomic and functional properties concurrently in post‐project appraisals. A better understanding of ecological recovery times should be incorporated into future restoration planning. Such evidence would help develop robust assessments over appropriate timescales, increasing the likelihood of accurately and effectively appraising restoration project success, and helping to build support to increase the scale and pace of restoration actions needed to address biodiversity loss.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185850","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}
C. Ryan Hill, Antóin M. O'Sullivan, J. Derek Hogan, R. Allen Curry, Tommi Linnansaari, Philip M. Harrison
We used PIT telemetry (n = 10,292 fish tagged) to evaluate upstream passage at a non‐volitional fishway (trap, lift, and truck) that passed approximately 10‐million river herring (alewife Alosa pseudoharengus and blueback herring A. aestivalis) around the lowermost dam in the Wolastoq/Saint John River, NB between 2020 and 2023. Between 26% and 62% of tagged fish reached the fishway crowding pool, while less than 14% were detected passing upstream. River herring experienced considerable passage delays (median = 3 days) after reaching the crowder entrance. The probability of passing on the date of first detection was only 10%, and it was positively correlated with the rate of fishway operation (i.e., fish lifts/unit time). The rate and probability of passage were greater for alewife than blueback herring and increased with total length for both species. Collectively, our results suggest that passage efficiency and duration were limited by the movement capacity and operation frequency of the fishway, and potentially the (high) number of fish attempting to pass at a given time. Ultimately, if the design and operation of non‐volitional fishways do not accommodate the size and behavior (i.e., schooling density and migration time) of target populations, our results indicate that potential consequences may include passage delays, reductions in passage efficiency, and selective pressures (e.g., size and species) on target populations.
{"title":"Limitations of Non‐Volitional Upstream Passage for Alewife (Alosa pseudoharengus) and Blueback Herring (Alosa aestivalis)","authors":"C. Ryan Hill, Antóin M. O'Sullivan, J. Derek Hogan, R. Allen Curry, Tommi Linnansaari, Philip M. Harrison","doi":"10.1002/rra.4372","DOIUrl":"https://doi.org/10.1002/rra.4372","url":null,"abstract":"We used PIT telemetry (<jats:italic>n</jats:italic> = 10,292 fish tagged) to evaluate upstream passage at a non‐volitional fishway (trap, lift, and truck) that passed approximately 10‐million river herring (alewife <jats:italic>Alosa pseudoharengus</jats:italic> and blueback herring <jats:italic>A</jats:italic>. <jats:italic>aestivalis</jats:italic>) around the lowermost dam in the Wolastoq/Saint John River, NB between 2020 and 2023. Between 26% and 62% of tagged fish reached the fishway crowding pool, while less than 14% were detected passing upstream. River herring experienced considerable passage delays (median = 3 days) after reaching the crowder entrance. The probability of passing on the date of first detection was only 10%, and it was positively correlated with the rate of fishway operation (i.e., fish lifts/unit time). The rate and probability of passage were greater for alewife than blueback herring and increased with total length for both species. Collectively, our results suggest that passage efficiency and duration were limited by the movement capacity and operation frequency of the fishway, and potentially the (high) number of fish attempting to pass at a given time. Ultimately, if the design and operation of non‐volitional fishways do not accommodate the size and behavior (i.e., schooling density and migration time) of target populations, our results indicate that potential consequences may include passage delays, reductions in passage efficiency, and selective pressures (e.g., size and species) on target populations.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224415","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}
Several rivers across the world face multiple threats from natural as well as human‐induced alterations in hydrology and morphology over time. Researchers have proposed several measures to instigate a healthier response by river rehabilitation or rejuvenation (depending on the condition of the river) to mitigate the impacts of causal factors. Investigating the causal factors of degradation is highly dependent on historical data, the availability of which depends on multiple considerations and is sometimes difficult to obtain, especially for a small river. A range of rehabilitation options have been explored by researchers among which geomorphology‐based approaches have gained importance as they are based on process‐based understanding and aim to reconstruct the river form for improving the river status. This paper introduces a novel method that uses very high‐resolution UAV data to analyze the topography and geomorphology of a small monsoon‐fed Sakri River in Central India. We aim to understand the anthropogenic factors responsible for its degradation with a particular focus on siltation and propose a river rejuvenation plan by creating the baseline data. The Sakri River supports 23 villages and a small town called Kawardha. The river presently has scanty surface flow and is unable to sustain the community. We mapped the entire river course using a UAV and identified 118 problematic sites, including 68 interventions along the 50 km stretch of the river. We have identified siltation as the primary problem at most sites caused by poorly designed interventions and a reduction in flow. We divided the river into 17 reaches and classified them into different states of criticality based on the identified problems and accumulated sediment volume behind the interventions. We have estimated a sizable volume of siltation within the 17 reaches as 0.5 million m3. Our analysis led to the development of a process response system that describes the various factors responsible for the degradation of the Sakri River and has important implications for designing mitigation strategies. Our recommendations for remedial measures are based on careful evaluation of the efficacy of each intervention and we have suggested their renovation or removal. We have also suggested reach‐specific solutions such as canal lining, river training, channel alignment, and river bank protection to be implemented.
{"title":"Integrating UAV‐Based Topographic and Geomorphic Analysis for the Development of River Rehabilitation Plans in Semi‐Urban Settings","authors":"Dipro Sarkar, Rajiv Sinha","doi":"10.1002/rra.4371","DOIUrl":"https://doi.org/10.1002/rra.4371","url":null,"abstract":"Several rivers across the world face multiple threats from natural as well as human‐induced alterations in hydrology and morphology over time. Researchers have proposed several measures to instigate a healthier response by river rehabilitation or rejuvenation (depending on the condition of the river) to mitigate the impacts of causal factors. Investigating the causal factors of degradation is highly dependent on historical data, the availability of which depends on multiple considerations and is sometimes difficult to obtain, especially for a small river. A range of rehabilitation options have been explored by researchers among which geomorphology‐based approaches have gained importance as they are based on process‐based understanding and aim to reconstruct the river form for improving the river status. This paper introduces a novel method that uses very high‐resolution UAV data to analyze the topography and geomorphology of a small monsoon‐fed Sakri River in Central India. We aim to understand the anthropogenic factors responsible for its degradation with a particular focus on siltation and propose a river rejuvenation plan by creating the baseline data. The Sakri River supports 23 villages and a small town called Kawardha. The river presently has scanty surface flow and is unable to sustain the community. We mapped the entire river course using a UAV and identified 118 problematic sites, including 68 interventions along the 50 km stretch of the river. We have identified siltation as the primary problem at most sites caused by poorly designed interventions and a reduction in flow. We divided the river into 17 reaches and classified them into different states of criticality based on the identified problems and accumulated sediment volume behind the interventions. We have estimated a sizable volume of siltation within the 17 reaches as 0.5 million m<jats:sup>3</jats:sup>. Our analysis led to the development of a process response system that describes the various factors responsible for the degradation of the Sakri River and has important implications for designing mitigation strategies. Our recommendations for remedial measures are based on careful evaluation of the efficacy of each intervention and we have suggested their renovation or removal. We have also suggested reach‐specific solutions such as canal lining, river training, channel alignment, and river bank protection to be implemented.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185817","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}
Matthew J. Burnett, Gordon C. O'Brien, Andrew Blackmore, Melissa Wade, Colleen T. Downs
In South Africa, fish kill events are increasing in frequency because of multiple stressors associated with managing natural resources. Despite the ecosystem services associated with fish, South Africa's progressive legislation towards environmental protection seems to negate the management of fish kills. In this study, we provide an overview of reports and regulations associated with acute pollution spills resulting in fish kill events in South Africa. In addition, we highlight the implication of these using a fish kill event from 2019 on the Msunduzi River, South Africa, as a case study. The fish kill on the Msunduzi River showed a decline in relative abundance by up to 41%, and its ecological condition was already impaired by poor management. The poor condition of the Msunduzi River has jeopardised the recovery of the fish populations, and intervention is needed to restore the fish population that includes species red‐listed as vulnerable by the International Union for the Conservation of Nature. We found that despite the severity of fish kills and the detriment to the fish fauna, including near‐threatened species, there is a general apathy, incapacity and lack of knowledge on managing fish kills in South Africa. In addition, although several legislated Acts have good intentions for protecting nature, they do not align and show that a fish kill is an afterthought rather than a need to prevent. Poor management practices have exacerbated this in an already stressed state from excessive use of environmental water. As a way forward, the alignment of the various Acts associated with various ministerial departments in South Africa is needed so that better protection of the environment may occur. Finally, we argue that the African proverb ‘If the fish comes out of the river to tell you that the crocodile has one eye, you should believe it’ is not considered when managing water resources and that with the present ecological state and water resource use there may be no fish to ‘come out of the water’ warning us that our water is unsafe even for human consumption and use.
{"title":"If a fish comes out of the river and speaks, we should believe it: South African perspective on fish kills","authors":"Matthew J. Burnett, Gordon C. O'Brien, Andrew Blackmore, Melissa Wade, Colleen T. Downs","doi":"10.1002/rra.4359","DOIUrl":"https://doi.org/10.1002/rra.4359","url":null,"abstract":"In South Africa, fish kill events are increasing in frequency because of multiple stressors associated with managing natural resources. Despite the ecosystem services associated with fish, South Africa's progressive legislation towards environmental protection seems to negate the management of fish kills. In this study, we provide an overview of reports and regulations associated with acute pollution spills resulting in fish kill events in South Africa. In addition, we highlight the implication of these using a fish kill event from 2019 on the Msunduzi River, South Africa, as a case study. The fish kill on the Msunduzi River showed a decline in relative abundance by up to 41%, and its ecological condition was already impaired by poor management. The poor condition of the Msunduzi River has jeopardised the recovery of the fish populations, and intervention is needed to restore the fish population that includes species red‐listed as vulnerable by the International Union for the Conservation of Nature. We found that despite the severity of fish kills and the detriment to the fish fauna, including near‐threatened species, there is a general apathy, incapacity and lack of knowledge on managing fish kills in South Africa. In addition, although several legislated Acts have good intentions for protecting nature, they do not align and show that a fish kill is an afterthought rather than a need to prevent. Poor management practices have exacerbated this in an already stressed state from excessive use of environmental water. As a way forward, the alignment of the various Acts associated with various ministerial departments in South Africa is needed so that better protection of the environment may occur. Finally, we argue that the African proverb ‘<jats:italic>If the fish comes out of the river to tell you that the crocodile has one eye, you should believe it</jats:italic>’ is not considered when managing water resources and that with the present ecological state and water resource use there may be no fish to ‘come out of the water’ warning us that our water is unsafe even for human consumption and use.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185849","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}
Hydropower facilities can alter river flow regimes, leading to ecological degradation and conflicts between revenue generation and ecological objectives. This study develops a new and unique framework (FREE—Flexible Releases for Economics and the Environment) for hydropower management that uses operational flexibility to balance economic and ecological objectives that are, respectively, maximized through unrestricted hydropeaking and maintaining natural flows. FREE integrates flexibility by permitting reservoir releases to deviate from inflows when power generation is most economically valuable. Operational flexibility is characterized by the magnitude and frequency of deviations from an inflow‐equals‐outflow (IEO) regime and is applied seasonally to reflect varying economic and ecological needs throughout the year. FREE is implemented using an optimization model applied to three hydropeaking facilities on the mainstem Connecticut River that are currently in a relicensing process. Estimated impacts of operational flexibility are quantified on annual and seasonal scales, with economic goals measured by power and revenue, and ecological goals by a proxy measure: the Richard‐Baker flashiness (RBF) index. To explore operational flexibility, two inflow regimes are investigated: existing inflows, which are altered by upstream hydropower operations, and estimated unaltered inflows. FREE was presented to interested parties engaged in the Connecticut River relicensing process, where it was applied in collaborative negotiations designed to develop integrated, dynamic, economically viable, and ecologically supportive hydropower operations. Trade‐offs between estimated revenue generation and RBF, as applicable to these interested parties, were presented along a Pareto frontier.
{"title":"Timing is everything: Rethinking flexible hydropower operations for the economy and environment","authors":"Sarah Pfeifle, Katie Kennedy, Richard Palmer","doi":"10.1002/rra.4370","DOIUrl":"https://doi.org/10.1002/rra.4370","url":null,"abstract":"Hydropower facilities can alter river flow regimes, leading to ecological degradation and conflicts between revenue generation and ecological objectives. This study develops a new and unique framework (FREE—Flexible Releases for Economics and the Environment) for hydropower management that uses operational flexibility to balance economic and ecological objectives that are, respectively, maximized through unrestricted hydropeaking and maintaining natural flows. FREE integrates flexibility by permitting reservoir releases to deviate from inflows when power generation is most economically valuable. Operational flexibility is characterized by the magnitude and frequency of deviations from an inflow‐equals‐outflow (IEO) regime and is applied seasonally to reflect varying economic and ecological needs throughout the year. FREE is implemented using an optimization model applied to three hydropeaking facilities on the mainstem Connecticut River that are currently in a relicensing process. Estimated impacts of operational flexibility are quantified on annual and seasonal scales, with economic goals measured by power and revenue, and ecological goals by a proxy measure: the Richard‐Baker flashiness (RBF) index. To explore operational flexibility, two inflow regimes are investigated: existing inflows, which are altered by upstream hydropower operations, and estimated unaltered inflows. FREE was presented to interested parties engaged in the Connecticut River relicensing process, where it was applied in collaborative negotiations designed to develop integrated, dynamic, economically viable, and ecologically supportive hydropower operations. Trade‐offs between estimated revenue generation and RBF, as applicable to these interested parties, were presented along a Pareto frontier.","PeriodicalId":21513,"journal":{"name":"River Research and Applications","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185819","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}
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