- Regional Controls on Physical Habitat Structure of Amazon Streams
- Authors: N. L. Benone; M. C. Esposito, L. Juen, P. S. Pompeu, L. F. A. Montag
Abstract: Drainage basins are inherently hierarchical and are composed of a series of nested subsystems, in which the functions and structure of lower levels depend on the features of higher levels. For a comprehensive understanding of the functioning of river systems, it is necessary to identify which factors are important at different scales and how they interact. Considering the importance of assessing lotic systems in the Amazon, our aim was to answer the following question: how do regional features at catchment scale constrain local physical habitat of streams? We sampled 55 streams distributed among six protected river basins of the Amazon, examining the associations of 11 catchment metrics with 146 local variables describing physical habitat structure derived from field measurements. Multivariate analyses showed that basins were structured according to different factors at both scales; variables related to substrate, cover for aquatic organisms and fast channel habitats were explained by altitude, catchment slope and proportion of coarse fragments in soils. Altitude was the most important catchment variable, strongly affecting flow velocity and regulating channel morphology and sediment transport. Spatial differences in environmental heterogeneity indicate that different processes act at each scale; this emphasizes how difficult it is to choose the most relevant spatial scale in ecological studies. Our results highlight the importance of regional variables, especially altitude and slope, as drivers of local-scale environmental heterogeneity. We hope these results will help in developing more efficient monitoring projects and restoration practices to better understand and conserve aquatic resources in the Amazon Basin. Copyright © 2017 John Wiley & Sons, Ltd.
- Spatial and Temporal Dynamics of Suspended Particle Characteristics and
Composition in Navigation Pool 19 of the Upper Mississippi River
- Authors: A. S. Milde; W. B. Richardson, E. A. Strauss, J. H. Larson, J. M. Vallazza, B. C. Knights
Abstract: Suspended particles are an essential component of large rivers influencing channel geomorphology, biogeochemical cycling of nutrients, and food web resources. The Upper Mississippi River is a large floodplain river that exhibits pronounced spatiotemporal variation in environmental conditions and biota, providing an ideal environment for investigating dynamics of suspended particles in large river ecosystems. Here we investigated two questions: (i) How do suspended particle characteristics (e.g. size and morphology) vary temporally and spatially? and (ii) What environmental variables have the strongest association with particle characteristics? Water sampling was conducted in June, August, and September of 2013 and 2014 in Navigation Pool 19 of the Upper Mississippi River. A FlowCAM® (Flow Cytometer and Microscope) particle imaging system was used to enumerate and measure particles 53–300 μm in diameter for size and shape characteristics (e.g. volume, elongation, and symmetry). Suspended particle characteristics varied considerably over space and time and were strongly associated with discharge and concentrations of nitrate + nitrite (NO3−) and soluble reactive phosphorus. Particle characteristics in backwaters were distinct from those in other habitats for most of the study period, likely due to reduced hydrologic connectivity and higher biotic production in backwaters. During low discharge, phytoplankton and zooplankton made up relatively greater proportions of the observed particles. Concurrently during low discharge, concentrations of chlorophyll, volatile suspended solids, and total phosphorus were higher. Our results suggest that there are complex interactions among space, time, discharge, and other environmental variables (e.g. water nutrients), which drive suspended particle dynamics in large rivers. Copyright © 2017 John Wiley & Sons, Ltd.
- Do Alluvial Sand Dunes Create Energetic Refugia for Benthic Fishes? An
Experimental Test with the Endangered Pallid Sturgeon
- Authors: A. P. Porreca; W. D. Hintz, J. E. Garvey
Abstract: River modifications have altered critical habitats for fishes at a variety of spatial scales and caused global declines of many fluvial species. At small spatial scales (
- Predicted Native Fish Response, Potential Rewards and Risks from Flow
Alteration in a New Mexico Arid Mountain Stream
- Authors: W. E. Pine; J. Caldwell, M. Allen, C. Stropki
Abstract: Water and natural resource managers are concerned with evaluating how fish habitat and populations may respond to water diversions and small-scale flow augmentations. We used two-dimensional hydraulic models, habitat suitability curves and an individual-based population viability model to assess whether flow augmentations of about 0.28–0.57 m3/s would create suitable habitat for federally listed native fish loach minnow Rhinichthys cobitis and spikedace Meda fulgida in a reach of the Gila River, New Mexico, and then examined how fish population viability may change under a variety of colonization and extinction scenarios. These simulations help to inform water management decisions in a reach of the Gila River where river diversions currently exist and new diversions and augmentations are being proposed. Our results suggest that the flow augmentations evaluated will result in small changes (on average across life stages, −0.22% to 4.06%) in suitable habitat for loach minnow and spikedace depending on augmentation scenario and fish life stage. While these percent changes are small, they would result in a reduction in the dewatering of the river channel in a river reach where native fish abundance is thought to be low. Actual native fish responses to these habitat changes are unknown; however, these flow augmentations could potentially allow these native species to re-colonize this river segment from upstream or downstream sources increasing species distribution and likely population viability. Maintaining viable populations of native fish in this river reach is dependent on complex factors including persistence of suitable habitat for multiple life stages, connectivity with other populations and minimizing risk of invasion from non-native species. We recommend that these predictions from the habitat and population models be tested and verified in an adaptive management framework linking modelling, experimental management, monitoring and reassessment to inform water management decisions in the Gila River. Copyright © 2017 John Wiley & Sons, Ltd.
- Spatial and Temporal Relationships Between the Invasive Snail Bithynia
tentaculata and Submersed Aquatic Vegetation in Pool 8 of the Upper
- Authors: A. M. Weeks; N. R. De Jager, R. J. Haro, G. J. Sandland
Abstract: Bithynia tentaculata is an invasive snail that was first reported in Lake Michigan in 1871 and has since spread throughout a number of freshwater systems of the USA. This invasion has been extremely problematic in the Upper Mississippi River as the snails serve as intermediate hosts for several trematode parasites that have been associated with waterfowl mortality in the region. This study was designed to assess the abundance and distribution of B. tentaculata relative to submersed aquatic vegetation as macrophytes provide important nesting and food resources for migrating waterfowl. Temporal changes in both vegetation and snail densities were compared between 2007 and 2015. Between these years, B. tentaculata densities have nearly quadrupled despite minor changes in vegetation abundance, distribution and composition. Understanding the spatial distribution of B. tentaculata in relation to other habitat features, including submersed vegetation, and quantifying any further changes in the abundance and distribution of B. tentaculata over time will be important for better identifying areas of risk for disease transmission to waterfowl. Copyright © 2017 John Wiley & Sons, Ltd.
- A Histogram Comparison Approach for Assessing Hydrologic Regime Alteration
- Authors: F. Huang; F. Li, N. Zhang, Q. Chen, B. Qian, L. Guo, Z. Xia
Abstract: The histogram comparison approach (HCA) is proposed to assess the alteration of hydrologic regimes, which are characterized by the hydrologic metrics, for example, the indicators of hydrologic alteration. The HCA method considers alterations within the whole range of the hydrologic regime and estimates the alteration degree by comparing the pre-impact and post-impact histograms. A key parameter of the HCA method is the similarity degree, which considers both the class-by-class and cross-class information of histograms and reflects how many features of the pre-impact histogram remain in the post-impact histogram. The alteration degree is defined as the mathematical maximum similarity degree, that is, 100%, subtracted by the actual similarity degree in the HCA method. Comparing the HCA method to the existing range of variability approach and histogram matching approach through theoretical analysis and case studies, the HCA method can eliminate some limitations of the range of variability approach and histogram matching approach methods and can more accurately and effectively assess the hydrologic regime alteration. The Ob and Yangtze Rivers, which are located in different climatic zones, are used as case studies. Hydrologic regime alterations impacted by reservoirs with different regulation abilities (daily, seasonally and yearly) were assessed using the HCA method, the results of which verified its rationality and practicability. More sites with a wider range of flow variations will be examined in the future to assess the applicability of the HCA method. Copyright © 2017 John Wiley & Sons, Ltd.
- Comparison of Taxon-Specific and Taxon-Generic Risk Screening Tools to
Identify Potentially Invasive Non-native Fishes in the River Neretva
Catchment (Bosnia and Herzegovina and Croatia)
- Authors: B. Glamuzina; P. Tutman, V. Nikolić, Z. Vidović, J. Pavličević, L. Vilizzi, G. H. Copp, P. Simonović
Abstract: The Freshwater Fish Invasiveness Screening Kit (FISK) v2 and Aquatic Species Invasiveness Screening Kit (AS-ISK) risk identification screening tools were used to assess the invasiveness potential of 24 non-native (NNS) freshwater fish species in the River Neretva catchment (Bosnia and Herzegovina and Croatia), a risk assessment (RA) area that is an important Mediterranean hotspot for fish endemism. The two assessors assigned similar scores for the invasiveness potential of the NN fishes, and both screening tools successfully distinguished invasive from non-invasive species. Mean calibrated threshold scores were 10.25 for FISK and 10.00 for AS-ISK, with the latter increasing to 12.62 when questions that assess the likely impact of predicted future climate conditions on the RA were taken into consideration. These relatively low threshold values are characteristic of areas with an elevated number of translocated species and suggest that NN fishes pose a considerable threat to native species and ecosystems. FISK ranked 50.0–62.6% of the species as being of ‘high risk’ compared with 58.4–59.3% using AS-ISK. The highest scores (‘very high risk’) were attributed to gibel carp Carassius gibelio (Bloch, 1782) and pikeperch Sander lucioperca (Linnaeus, 1758). The generic screening tool for aquatic species (AS-ISK) provided similar risk rankings to its predecessor, FISK, as regards invasiveness potential. For this reason, it is likely to be an effective tool for evaluating the potential invasion risk of NNS freshwater fishes for other RA areas in the Balkans. Copyright © 2017 John Wiley & Sons, Ltd.
- Low-Head Dam Impacts on Habitat and the Functional Composition of Fish
- Authors: S. C. F. Smith; S. J. Meiners, R. P. Hastings, T. Thomas, R. E. Colombo
Abstract: The natural flow regime of many rivers in the USA has been impacted by anthropogenic structures. This loss of connectivity plays a role in shaping river ecosystems by altering physical habitat characteristics and shaping fish assemblages. Although the impacts of large dams on river systems are well documented, studies on the effects of low-head dams using a functional guild approach have been fewer. We assessed river habitat quality and fish community structure at 12 sites on two rivers; the study sites included two sites below each dam, two sites in the pool above each dam and two sites upstream of the pool extent. Fish communities were sampled from 2012 to 2015 using a multi-gear approach in spring and fall seasons. We aggregated fishes into habitat and reproductive guilds in order to ascertain dams' effects on groups of fishes that respond similarly to environmental variation. We found that habitat quality was significantly poorer in the artificial pools created above the dams than all other sampling sites. Fast riffle specialist taxa were most abundant in high-quality riffle habitats farthest from the dams, while fast generalists and pelagophils were largely restricted to areas below the downstream-most impoundment. Overall, these dams play a substantial role in shaping habitat, which impacts fish community composition on a functional level. Utilizing this functional approach enables us to mechanistically link the effects of impoundments to the structure of fish communities and form generalizations that can be applied to other systems. Copyright © 2017 John Wiley & Sons, Ltd.
- Uncertainty Estimation in Flood Inundation Mapping: An Application of
- Authors: M. Faghih; M. Mirzaei, J. Adamowski, J. Lee, A. El-Shafie
Abstract: Disaster prevention planning is affected in a significant way by a lack of in-depth understanding of the numerous uncertainties involved with flood delineation and related estimations. Currently, flood inundation extent is represented as a deterministic map without in-depth consideration of the inherent uncertainties associated with variables such as precipitation, streamflow, topographic representation, modelling parameters and techniques, and geospatial operations. The motivation of this study is to estimate uncertainties in flood inundation mapping based on a non-parametric bootstrapping method. The uncertainty is addressed through the application of non-parametric bootstrap sampling to the hydrodynamic modelling software, HEC-RAS, integrated with Geographic Information System (GIS). This approach was used to simulate different water levels and flow rates corresponding to different return periods from the available database. The study area was the Langat River Basin in Malaysia. The results revealed that the inundated land and infrastructure are subject to a flooding hazard of high-frequency events and that the flood damage potential is increasing significantly for residential areas and valuable land-use classes with higher return periods. The proposed methodology, as well as the study outcomes, of this paper could be beneficial to policymakers, water resources managers, insurance companies and other flood-related stakeholders. Copyright © 2017 John Wiley & Sons, Ltd.
- Macro-invertebrate Community Response to Multi-annual Hydrological
- Authors: Visser A; Beevers L, Patidar S.
Abstract: Flow is widely considered one of the primary drivers of instream ecological response. Increasingly, hydroecological models form the basis of integrated and sustainable approaches to river management, linking flow to ecological response. In doing so, the most ecologically relevant hydrological variables should be selected. Some studies have observed a delayed macro-invertebrate (ecological) response to these variables (i.e. a cumulative inter-annual effect, referred to as multi-annual) in groundwater-fed rivers. To date, only limited research has been performed investigating this phenomenon. This paper examines the ecological response to multi-annual flow indicators for a groundwater-fed river. Relationships between instream ecology and flow were investigated by means of a novel methodological framework developed by integrating statistical data analysis and modelling techniques, such as principal component analysis and multistep regression approaches. Results demonstrated a strong multi-annual multi-seasonal effect. Inclusion of additional antecedent flows indicators appears to enhance overall model performance (in some cases, goodness of fit statistics such as the adjusted R-squared value exceeded 0.6). These results strongly suggest that, in order to understand potential changes to instream ecology arising from changing flow regimes, multi-annual and multi-seasonal relationships should be considered in hydroecological modelling. Copyright © 2017 John Wiley & Sons, Ltd.
- Bioaccumulation of Inorganic Elements in Dreissena polymorpha from the
Ebro River, Spain: Could Zebra Mussels Be Used as a Bioindicator of the
Impact of Human Activities?
- Authors: M. Benito; R. Mosteo, E. Rubio, D. LaPlante, M. P. Ormad, P. Goñi
Abstract: Dreissena polymorpha is among the top 100 most harmful invasive species in aquatic habitats. European Directive 2013/39/UE establishes Environmental Quality Standards for biota because it has been demonstrated that pollutants bioaccumulate in aquatic organisms. This study evaluated bioaccumulation of inorganic elements in the soft tissues of D. polymorpha in order to assess the usefulness of zebra mussels as a bioindicator of contaminant presence in superficial waters. Concentrations of 66 elements were measured in order to evaluate their relationship with nearby anthropogenic activity and to the values recommended by Environmental Quality Standards for biota. Bivalves were collected from four sample points along the Ebro River Basin (Spain), where diverse human activities are carried out. Zebra mussels accumulate toxins in soft tissue during their life cycle, including Al, Cr, Fe, Hg, Pb, Th, Cd and U. The highest levels of accumulation corresponded to elements associated with human activity in the area, showing the impact of anthropogenic actions on biota. D. polymorpha not only supplies information about current water quality but also acts as a witness of past water quality by bioconcentrating toxic elements present in the environment and providing relevant results about historical water contamination. In conclusion, D. polymorpha is a harmful and dangerous invasive species, but its pervasiveness means that it can be used as a bioindicator to assess current and past presence of elements in water. Copyright © 2017 John Wiley & Sons, Ltd.
- The Transferability of Terrestrial Water Balance Components under
Uncertainty and Nonstationarity: A Case Study of the Coastal Plain
Watershed in the Southeastern USA
- Authors: S. Z. Samadi; M. E. Meadows
Abstract: The challenges posed by nonstationarity in predicting catchment water balance components motivated this study to test the stationary versus nonstationarity hypothesis and detect changes in the watershed response to land use land cover (LULC) alterations, and climate variability and change. The focus is on a two-step procedure that includes model calibration of Soil and Water Assessment Tool using a sequential Bayesian uncertainty algorithm (i.e. sequential uncertainty fitting), followed by nonstationary assessment of water balance component using extreme value analysis over an Atlantic coastal plain watershed in the southeastern USA. Analysis suggests that the uncertainty of Soil and Water Assessment Tool model is statistically aligned with LULC alterations that increased the sensitivity of Manning's roughness coefficient, transmission loss and the resistance of the soil matrix to water flow. Changes in LULC along with variability in the magnitude, timing and frequency of precipitation diminished surface runoff and groundwater contribution to the river system whereas it increased evapotranspiration with a substantial decline in water storage capacity. Nonstationary assessment of water balance using extreme value analysis model further revealed a functional form of stationary behaviour (no trends) prior to LULC alteration while large amplification was detected during post-changes. The results and findings presented in this paper confirm our hypothesis about a combined effect of climate and LULC changes on hydrological functions and that variation of these fingerprints elucidates the presence of nonstationarity in the watershed system. Copyright © 2017 John Wiley & Sons, Ltd.
- Borders and Barriers: challenges of Fisheries Management and Conservation
in Open Systems
- Authors: S. F. Siddons; M. A. Pegg, G. M. Klein
Abstract: Large rivers often bisect geopolitical boundaries where management goals may be at odds for a shared fishery, creating fragmented management zones. Fragmentation due to physical barriers may further impact the fishery by reducing fish passage. Our goal was to estimate basin-wide parameters (i.e. movement, survival and capture probabilities) of a large-river species known to move throughout watersheds. We tagged13 892 Channel Catfish in the Red River of the North (Red River) and Lake Winnipeg in Manitoba, Canada, and collected 553 recaptures. We estimated 2.2% of catfish are moving from the Red River to Lake Winnipeg each month and 9.4%, primarily large (>600 mm) individuals, moved upstream through a dam (monthly). Approximately 5.6% of catfish moved to the USA each month, and only one fish returned. Our results suggest the lower reaches of the Red River may be a source population for the USA, where survival is lower, and Lake Winnipeg. The complex movements of Channel Catfish throughout the Red River, across barriers and international boundaries, suggest conservation and management of fish populations should be watershed wide. Copyright © 2017 John Wiley & Sons, Ltd.
- Evaluating the Framework of a New River Bird Survey Method
- Authors: E. M. Call; M. L. Hunter
Abstract: River bird assemblages can serve as beacons of environmental change associated with restoration or degradation. River birds regularly rely on riverine resources at some point in their life cycle, vary in the scale of temporal and spatial of use and forage at multiple levels of the food web (e.g. fish, aquatic plants, aquatic or emergent insects). We present a novel river bird survey method that is more easily employed and less intrusive than riverbank transect or boat surveys and encompasses a wide suite of species and a year-round time frame. We evaluate the relative efficacy of different levels of survey duration (20, 15, 10 or 5 min), number of surveys (every 2 weeks in spring and fall and every 3 weeks in summer and winter) and number of sites on the survey's ability to document species richness and bird abundance. We used two statistical approaches, species accumulation curves (for duration, number of surveys and number of sites) and first-order Jackknifes (for duration). We conclude that a biweekly or triweekly survey, 25 sites in the focal river, and a survey duration of at least 15 min are sufficient to meet our objectives. This logistically efficient survey approach facilitates monitoring complex and long-term change such as that associated with river restoration and dam removal. Copyright © 2017 John Wiley & Sons, Ltd.
- Quantifying Fish Habitat Associated with Stream Simulation Design Culverts
in Northern Wisconsin
- Authors: A. Timm; D. Higgins, J. Stanovick, R. Kolka, S. Eggert
Abstract: This study investigated the effects of culvert replacement design on fish habitat and fish weight by comparing substrate diversity and weight at three stream simulation (SS)-design and three bankfull and backwater (BB)-design sites on the Chequamegon-Nicolet National Forest, Wisconsin. Stream channel cross-sections, Wolman substrate particle counts, and single-pass backpack electro-fishing survey data were used to quantify fish habitat and fish weight in 50-m upstream and downstream sample reaches at each site. We applied generalized linear mixed models to test the hypothesis that substrate size and fish weight did not differ according to stream-crossing design type (SS or BB) and location (upstream or downstream). Substrate particle sizes were significantly greater upstream of the stream crossing when compared to downstream of the stream crossing at both SS and BB sites for riffles and pools. Substrate particle sizes were also significantly greater upstream of BB sites when compared to upstream of SS sites. Results of this study indicated statistically greater individual fish weights upstream of SS-design sites in comparison to upstream of BB-design sites in first- to third-order low gradient streams. These results suggested that the SS-design approach appears to be more effective at transporting sediment downstream, and illustrated the value of using fish weight as an indicator of biological success for stream-crossing designs. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.
- Evaluating the Effects of Culvert Designs on Ecosystem Processes in
Northern Wisconsin Streams
- Authors: J. C. Olson; A. M. Marcarelli, A. L. Timm, S. L. Eggert, R. K. Kolka
Abstract: Culvert replacements are commonly undertaken to restore aquatic organism passage and stream hydrologic and geomorphic conditions, but their effects on ecosystem processes are rarely quantified. The objective of this study was to investigate the effects of two culvert replacement designs on stream ecosystem processes. The stream simulation design, where culverts accommodate bankfull width and streambeds are reconstructed through the culvert, was compared with the bankfull and backwater design, where streambeds were left to fill naturally, as well as to non-replaced culverts. We predicted that stream simulation culverts would best preserve water velocity and coarse particulate organic matter (CPOM) retention within the culvert relative to upstream reaches, and that both replaced culvert styles would exhibit rates closer to upstream reaches than non-replaced culverts. In addition, we predicted that ecosystem processes (CPOM retention, transient storage and nutrient uptake) would be similar in reaches upstream and downstream of both replaced culvert styles, because both designs are constructed to maintain stream slopes and bankfull widths through the structure. We found that stream simulation design better maintained CPOM retention through culverts compared with non-replaced and bankfull and backwater design culverts, but observed no differences in ecosystem processes between reaches located upstream or downstream of replaced culverts. Although the stream simulation design requires additional streambed construction relative to the bankfull and backwater design, this step may lead to additional improvement if maintaining ecological conditions through the culvert is an important restoration goal. Copyright © 2017 John Wiley & Sons, Ltd.
- Issue Information
- Pages: 187 - 188
Abstract: No abstract is available for this article.
- From Microhabitat Ecohydraulics to an Improved Management of River
Catchments: Bridging the gap Between Scales
- Authors: Atle Harby; Francisco Martinez- Capel, Nicolas Lamouroux
Pages: 189 - 191
- Note: Hy:Con: A Strategic Tool For Balancing Hydropower Development And
- Authors: C. Seliger; S. Scheikl, S. Schmutz, R. Schinegger, S. Fleck, J. Neubarth, C. Walder, S. Muhar
Pages: 276 - 276
Abstract: The article from this special issue was previously published in River Research and Applications, Volume 32, Issue 7, 2016. For completeness we are including the title page of the article below. The full text of the article can be read in Issue 32:7 on Wiley Online Library: http://onlinelibrary.wiley.com/doi/10.1002/rra.2985/abstract
- Survival of Migrating Sea Trout (Salmo trutta) Smolts During Their Passage
of an Artificial Lake in a Danish Lowland Stream
- Authors: M. Schwinn; K. Aarestrup, H. Baktoft, A. Koed
Abstract: Artificial lake development is often used as a management tool to reduce nutrient runoff to coastal waters. Denmark has restored more than 10 000 ha of wetlands and lakes in the last 14 years as a consequence of ‘Action Plans for the Aquatic Environment’, which aim to meet the demands of the European Union's Water Framework Directive. Juvenile, seaward migrating salmonids are highly affected by impounded waterbodies, as they are subjected to extraordinary high mortalities due to predation and altered habitat. From 2005 to 2015, survival and migration patterns of wild brown trout (Salmo trutta) smolts were investigated by using radio, acoustic and Passive Integrated Transponder telemetry both before and after the development of an artificial lake in a small Danish lowland stream. In 2005 and 2006, before the lake developed, survival was estimated to be 100% in the river stretch where the lake later developed. In 2007 and in the period between 2009 and 2015, mean yearly survival decreased to 26%. Mean time for passing the area increased significantly after the development of the lake from 0.42 to 5.95 days. Generalized additive models were used to model the probability of a successful passage. Water temperature and discharge were key environmental factors affecting survival of the smolts during the passage of the lake. Furthermore, smolt survival was negatively correlated with condition factor. This elevated level of smolt mortality may seriously compromise self-sustaining anadromous salmonid populations when artificial lakes are developed in connection with rivers. Copyright © 2016 John Wiley & Sons, Ltd.
- Flood Analysis Supported by Low-cost Geometric Modelling
- Authors: S. Zazo; P. Rodríguez-Gonzálvez, J.-L. Molina, D. Hernández-López, D. González-Aguilera
Abstract: Today, it is increasingly clear that non-stationarity hydrological and hydraulic variables and processes are occurring largely because of global warming. Accordingly, extreme hydrological events are becoming more common over time, and their effects are creating greater negative impacts on the environment (fluvial geomorphology and floodplains) and society (flood damage). Given this situation, the implementation of adaptation-mitigation measures is vital, as well as an increased knowledge of the interaction between water and physical environments. In the binominal water-terrain, having a reliable digital elevation model (DEM) is essential because of its important influence on fluvial modelling. However, this is frequently a technical-economic problem. The aim of this paper is first to evaluate the compatibility between hydraulics and geometrics for fluvial applications and second to determine the quality of a novel DEM by robust estimators. This was obtained through the photogrammetric processing of digital aerial images acquired from a low-cost camera mounted on an alternative aerial platform. Flood modelling and hydraulic parameters were obtained with the assistance of photogrammetric DEM (mesh size: 0.15 m, vertical accuracy: 0.102 ± 0.081 m, point density: ≈40 point/m2). Finally, our other goal is to develop a comparative analysis between light detection and ranging and digital photogrammetry on-demand. This comparison revealed that flood modelling by photogrammetric DEM was considerably more detailed than that by light detection and ranging-DEM, mainly because of higher point density and vertical accuracy. Consequently, flood analysis assisted by this novel geometric modelling approach qualifies as a reliable and competitive approach. Copyright © 2016 John Wiley & Sons, Ltd.
- Implementation of the Natural Flow Paradigm to Protect Dwarf Wedgemussel
(Alasmidonta heterodon) in the Upper Delaware River
- Authors: P. Parasiewicz; E. Castelli, J. N. Rogers, P. Vezza, A. Kaupsta
Abstract: This paper demonstrates the use of a multiplex habitat model for flow management criteria development compliant with the natural flow paradigm using the Upper Delaware River (NY/PA—USA) as an example. The goal of this study was to identify strategies to protect and support the recovery of the dwarf wedgemussel populations in the mainstem Delaware River. We quantified potential habitat, developed instreamflow recovery scenarios and modelled the scenario outcomes. Mesohabitat simulation model and River2D have been used to allow the transfer of suitability criteria between scales. Habitat time series were investigated with the help of the uniform continuous under threshold technique to establish natural habitat stressor thresholds.Exceedance of persistent and catastrophic durations results in habitat stress days (HSD). HSD served as a metric for the comparison of four flow and two habitat management scenarios. The greatest habitat improvements were accomplished through increasing the boundary Reynolds number, hence increasing the river bed diversity. The introduction of naturalized flows into the model did not cause any significant reduction of HSD, demonstrating that optimizing suitable habitat for dwarf wedgemussel may not be achieved without including morphological improvements. Both minimum and pulsed flow augmentation strategies were found to nullify rare stress days in our models. Our study found that, at a minimum, a pulsed flow regime would need to be created to promote the development of populations beyond the current mussel beds. To accomplish protection and enhancement of habitat fully, channel improvements that reduce boundary Reynolds number appear necessary. These recommendations are intended to create a starting point in the adaptive flow management process for the Upper Delaware River. Copyright © 2016 John Wiley & Sons, Ltd.
- Spatial and Temporal Distinction of Microelemental Signatures of Missouri
- Authors: M. R. Wuellner; J. D. Grote, M. J. Fincel
Abstract: The microchemical composition of a fish's calcified structure, such as an otolith, fin ray, or scale, is a ‘biological tag’ that reflects the use of different habitats throughout its life history. Hard-part microchemistry has the potential to address many fish conservation, management, and behavior questions. In order to use hard-part microchemistry to address fisheries research questions, elemental signatures of water must be distinct at the spatial scale of interest and ideally temporally stable. The goal of this study was to assess whether spatial differences existed in the concentrations of five elements [barium (137Ba), magnesium (24Mg), manganese (55Mn), sodium (23Na), and strontium (88Sr)] between and within eight Missouri River tributaries and whether those signatures were temporally stable. All elemental concentrations were converted to molar ratios (mmol mol−1) using calcium (43Ca) concentrations as the base. Canonical correspondence analysis showed distinct differences in Mg:Ca, Na:Ca, and Sr:Ca concentrations between the eight tributaries. Cochran–Mantel–Haenszel tests showed that sites within a tributary were distinguished using Mg:Ca and Na:Ca concentrations. However, only Mg:Ca concentrations were temporally stable. Results from this study demonstrate the potential for using hard-part microchemistry to address various questions at multiple spatial scales in the Missouri River riverscape but also highlight the importance of evaluating water microelemental signatures prior or simultaneous to any hard-part microchemistry study. Copyright © 2016 John Wiley & Sons, Ltd.
- Differences among Expert Judgments of Fish Habitat Suitability and
Implications for River Management
- Authors: J. Radinger; J. Kail, C. Wolter
Abstract: Expert judgment is regularly used in ecology for assessing the suitability of habitats, in particular of rare or endangered species or species with limited empirical data. Yet, differences in expert judgment of habitat suitability and consequent implications for ecosystem management have not been evaluated and are largely ignored.Here, we evaluated the variability of 13 expert judgments and the related uncertainty in hydraulic habitat suitability modelling using the riverine fish species Phoxinus phoxinus as a model species.We found (i) the highest agreement among experts identifying the best and fully unsuited habitat conditions, but (ii) that disagreement among experts is surprisingly large, (iii) with largest differences related to the experts' perception of flow velocity and (iv) that semi-suitable transition areas between high and low habitat suitability are most susceptible to disagreements.We emphasize that expert judgment of habitat suitability is useful for many applications and especially highly suitable habitats would be reliably identified by experts. However, expert judgment-based assessments should be iterative processes that include both different experts and feedback on the potential effects of their assessments. Furthermore, we recommend that expert judgment should not replace data-driven empirical ecology but its benefits can rather complement it. Copyright © 2016 John Wiley & Sons, Ltd.
- Response of Bed Sediments on the Grade-Control Structure Management of a
Small Piedmont Stream
- Authors: T. Galia; V. Škarpich
Abstract: The grain sizes of 53 small lateral and mid-channel deposits were evaluated on the 2.7 km long channel-reach of a headwater piedmont stream that has been affected by check-dams and bed sills constructions (ca. 14 constructions per km), riprap bank stabilisations and the removal of instream wood. Such interventions have led to the loss of natural vertically oscillating bedforms, and pool-riffles have been replaced by plane beds. The evaluated sediment deposits were divided based on their positions relative to grade-control structures on downstream, intermediate and upstream types. The individual types of deposits produced different downstream trends in the grain sizes that reflected their positions with respect to the grade-control structures (GCSs). The downstream deposits generally produced slow downstream coarsening, which may point to the increased efficiency of the energy dissipation of the GCSs under a gradual downstream decrease in the channel slopes. However, they were generally not coarser than the other two types. The upstream deposits did not indicate any notable downstream grain-size trend. Despite the significant downstream decrease in the channel slopes and related bankfull shear stresses at the positions of the intermediate deposits and the lack of a lateral sediment supply in the studied longitudinal profile, the sediment calibre of the deposits did not produce any systematic downstream fining. Thus, the observed grain sizes most likely pointed to the selective scouring of the fine sediments, which was caused by the presence of the GCSs and their effects on the decreasing sediment connectivity. Copyright © 2016 John Wiley & Sons, Ltd.
- The Effects of Rapid Water Level Changes on Fish Assemblages: The Case of
a Spillway Gate Collapse in a Neotropical Reservoir
- Authors: M. T. Baumgartner; G. Baumgartner, L. C. Gomes
Abstract: River damming and associated reservoir causes intense and dramatic changes that create new environments, with particular structure and functioning. In these systems, flow control and artificial variations in water level are important determinants of the structure of fish assemblages. Planned reduction in water level (drawdown) is used to manage productivity in reservoirs. However, the effects of non-planned reductions, such as those related to the collapse of spillway gates, are rarely studied. The objective of this study was to evaluate the effects of a rapid reservoir drawdown, because of the collapse of a gate, on the structure of fish assemblage in a Neotropical reservoir, in Southern Brazil, operated as run-of-the-river. Water level variation because of the collapse reached up to 20 m. A canonical analysis of principal coordinates (CAP) was used to summarize the structure of fish assemblage. Spearman rank correlations were performed between each CAP axes retained for interpretation and fish species abundances, to assess the ones that most contributed to observed patterns. The first CAP axis identified strong variations in the spatial scale, while the third axis identified variations in the time scale (before and after the collapse). The most notable negative effect was the loss of several fish that perished during the reservoir drawdown, probably because of adverse limnological conditions. Results showed significant benefits of water level variation on the entire fish assemblage, and we suggest that, observed some peculiarities, this variation can be used to manage reservoirs, as a tool to enhance fish abundances. Copyright © 2016 John Wiley & Sons, Ltd.
- Trend Analysis of Maximum Hydrologic Drought Variables Using
Mann–Kendall and Şen's Innovative Trend Method
- Authors: F. Tosunoglu; O. Kisi
Abstract: Droughts as destructive climatic extreme events affect natural environment of an area. Identifying droughts has a vital importance in the planning and management of water resource systems of a river basin. This study investigates the trends of maximum hydrologic drought variables, annual maximum duration (AMD), and annual maximum severity (AMS), by using Mann–Kendall, modified Mann–Kendall, and recently developed Şen's innovative trend analysis (ITA) methods. These methods are applied to the AMD and AMS of nine different stations located in Coruh River Basin, Turkey, in which numerous highly critical power plants have recently been constructed, under construction, or planned. Basic Mann–Kendall test indicated no trend in the investigated stations while the modified Mann–Kendall gave significantly decreasing trend for AMS series of station 2304 and for AMD series of station 2321 at 10% significance level. Modified Mann–Kendall and ITA approaches indicate that the AMS of station 2304 show significantly decreasing trend. According to the ITA method, the peak AMS values of the stations 2315 and 2322 have also significantly decreasing trend after 1986. Both modified MK and ITA methods provide increasing trends in drought severities of the stations 2316 and 2323. It should be noted that some droughts or water stress may be occurred in these stations in the future. Modified Mann–Kendall test provides no significant trend for the seven stations while ITA results indicated some positive or negative trends at these stations. The primary points of interest of Şen's ITA method are that it is not subject to any assumption such as serial relationship, non-normality, sample size, and trends of low, medium, and high data can be seen by this method easily. The study indicates that the ITA method could be simply and successfully used by hydrologist or water resources decision makers or in identifying droughts to prepare efficient management plans. Copyright © 2016 John Wiley & Sons, Ltd.
- Identification of Priority Areas for the Conservation of Stream Fish
Assemblages: Implications for River Management in France
- Authors: A. Maire; P. Laffaille, J.-F. Maire, L. Buisson
Abstract: Financial and human resources allocated to biodiversity conservation are often limited, making it impossible to protect all natural places, and priority areas for protection must be identified. In this study, we applied ecological niche models to predict fish assemblages in the stream network of France. Four non-correlated conservation objectives were derived from these species assemblages: taxonomic diversity, functional diversity, natural heritage importance and socio-economic value. We proposed a multi-objective prioritization method based on the Pareto optimality principle to rank the planning units (i.e. 6097 subcatchments) according to their inherent trade-offs between the four conservation objectives. Four types of hydrosystems of great conservation importance presenting specific fish assemblages were identified: (i) the most upstream areas of large catchments; (ii) the most downstream areas of large catchments; (iii) the small coastal catchments of the English Channel and the Atlantic Ocean; and (iv) the Mediterranean streams of medium altitude. The fish assemblages characterizing these hydrosystems were complementary and representative of the entire fish fauna of France. Most of these priority subcatchments were found to be practically suitable for the implementation of conservation actions, which is very promising for the protection of river biodiversity. Copyright © 2016 John Wiley & Sons, Ltd.
- Effects of Damming on Long-Term Development of Fluvial Islands, Elbe River
- Authors: P. Raška; M. Dolejš, M. Hofmanová
Abstract: Damming and water impoundment have fundamental influences on the geomorphology and ecological processes of lotic systems. Although these engineering projects affect all segments of the river channel, fluvial (mid-channel, river) islands are among the most threatened features because of their link to both hydrostatic and hydrodynamic effects of damming. In this study, we used historical maps (1843, 1852) and aerial photos (1954, 2014), as well as other written and iconographic documentary sources, to document the long-term development of the fluvial islands and channel planform in the Lower Labe (Elbe) River area (Northern Czechia) over the past ~170 years. Our results indicate the decrease of fluvial islands from 16 (1843), resp. 20 (1852) in the mid-19th century to eight in 1954, and finally to five in 2014. Most islands have disappeared because of the construction of dams and lock chambers for the purpose of river navigation in the first half of the 20th century. The possible processes responsible for island extinction in individual river segments include sediment starvation (downstream of the dam), erosion by overflow (near upstream of the dam) and decreased flow in inter-island branches (far upstream of the dam). The islands most susceptible to extinction are those with a smaller size and elliptical or irregular shape. Based on visual evaluation of historical photos and survey of present day temporary islands, the medium and fine sedimentary fraction and absence of a vegetation cover seem to be another predictor of island extinction. Finally, we stress the relevance of our findings for the current discussion on the construction of new lock chambers downstream of the study area. Copyright © 2016 John Wiley & Sons, Ltd.
- Hydropower Plant Operation Scenarios to Improve Brown Trout Habitat
- Authors: I. Pragana; I. Boavida, R. Cortes, A. Pinheiro
Abstract: In this study, different hydropower plant operation scenarios were proposed to assess the best habitat alternative for juvenile and adult brown trout (Salmo trutta). Habitat preferences were determined based on field data collection and translated into fuzzy sets and rules for both life-stages. The River2D model was applied to a 100-m long stream segment immediately downstream of the tailrace of the Ermida small hydropower plant (SHP) to obtain a 2D hydrodynamic description for different operation scenarios. Habitat modelling was performed using Casimir Fish 2D by combining flow and fuzzy rules. Overall, simulation results for the juveniles indicated its best habitat conditions for discharges between 0.5 and 1.0 m3s−1 and the adults for 5.0 m3s−1. Five main operation scenarios were developed according to the electricity pricing periods for dry, average and wet year. The decrease in energy revenue was calculated for each operation alternative. The results indicate that it was possible to reduce hydropeaking effects in brown trout habitat through changes in the hydropower plant operation especially for dry years. The methodology developed in this research should be seen as a decision-making tool to help water managers adapt hydropeaking regimes to reduce the ecological impact downstream of hydropower dams. Copyright © 2016 John Wiley & Sons, Ltd.
- Tracking Change in the Illinois River using Stable Isotopes in Modern and
- Authors: R. B. Brugam; K. Little, L. Kohn, P. Brunkow, G. Vogel, T. Martin
Abstract: The Illinois River has been heavily modified by human activities. We examined the nitrogen and carbon stable isotope composition of collagen from fish bones in two Native American middens comparing them to modern fishes in the River today. We also compared ancient and modern fishes to three reference samples—(i) Illinois River phytoplankton; (ii) backwater lake sediment; and (iii) tissue from riverside trees. We found a large increase in δ15N values in modern fish bone collagen relative to ancient collagen. However, there is little change in δ13C between ancient and modern samples. Bone collagen from invasive carp species (Hypopthalmichthys and Cyprinus) are similar to modern phytoplankton. All fishes are different from riverside trees and backwater lake sediment. The large shift in δ15N values between ancient and modern fishes is probably caused by contamination of the river by Chicago treated wastewater and by denitrified fertilizer run-off. Our results indicate a major change in nitrogen biogeochemistry in the modern river. Comparisons between ancient and modern δ13C values suggest little change in feeding behaviour of fishes between ancient and modern times. However, our data for invasive carp suggest strong competition with native planktivores. © 2016 The
Authors . River Research and Applications Published by John Wiley & Sons Ltd.
- Flood Effects Provide Evidence of an Alternate Stable State from Dam
Management on the Upper Missouri River
- Authors: K. Skalak; A. Benthem, C. Hupp, E. Schenk, J. Galloway, R. Nustad
Abstract: We examine how historic flooding in 2011 affected the geomorphic adjustments created by dam regulation along the approximately 120 km free flowing reach of the Upper Missouri River bounded upstream by the Garrison Dam (1953) and downstream by Lake Oahe Reservoir (1959) near the City of Bismarck, ND, USA. The largest flood since dam regulation occurred in 2011. Flood releases from the Garrison Dam began in May 2011 and lasted until October, peaking with a flow of more than 4200 m3 s−1. Channel cross-section data and aerial imagery before and after the flood were compared with historic rates of channel change to assess the relative impact of the flood on the river morphology. Results indicate that the 2011 flood maintained trends in island area with the loss of islands in the reach just below the dam and an increase in island area downstream. Channel capacity changes varied along the Garrison Segment as a result of the flood. The thalweg, which has been stable since the mid-1970s, did not migrate. And channel morphology, as defined by a newly developed shoaling metric, which quantifies the degree of channel braiding, indicates significant longitudinal variability in response to the flood. These results show that the 2011 flood exacerbates some geomorphic trends caused by the dam while reversing others. We conclude that the presence of dams has created an alternate geomorphic and related ecological stable state, which does not revert towards pre-dam conditions in response to the flood of record. This suggests that management of sediment transport dynamics as well as flow modification is necessary to restore the Garrison Segment of the Upper Missouri River towards pre-dam conditions and help create or maintain habitat for endangered species. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.
- An Objective Method to Prioritize Socio-Environmental Water Management
Tradeoffs Using Multi-Criteria Decision Analysis
- Authors: D. M. Martin; S. J. Powell, J. A. Webb, S. J. Nichols, N. L. Poff
Abstract: Rivers provide many social and environmental services that benefit humanity. A critical role of water mangers is to prioritize water allocation options that trade off socio-economic and hydro-ecological benefits in rivers. Methods for multi-criteria decision analysis (MCDA) provide a structured and systematic manner for researchers to aid in this process. In this paper, we describe a new MCDA method that prioritizes large multi-dimensional sets of tradeoffs to support well-informed water management in rivers. The method was developed based on an environmental flows planning study in the Goulburn-Broken River catchment, Victoria, Australia. A combined simulation and heuristic optimization procedure was previously integrated into a hydrological catchment network model. That process resulted in a large set of viable daily water allocation schedules that traded off long-term irrigation and hydro-ecological benefits at the catchment outlet. We provided new guidance procedures to identify priority tradeoffs that can be used in stakeholder deliberations and catchment decision-making. Our MCDA method included combined multi-dimensional ordination and cluster analysis to spread the water allocation alternatives onto a two-dimensional plane to discover alternatives with similar criteria tradeoffs. A geometric distance-based method was performed on the full set of alternatives and on the identified clusters to rank the alternatives in accordance with minimizing the distance of the alternatives to an ideal but non-feasible reference point in multi-dimensional space. This method complements the use of elicitation procedures when water manager or other stakeholder interaction is not an option or when objectivity is desired. Copyright © 2016 John Wiley & Sons, Ltd.
- Macroinvertebrate Functional Trait Responses to Chemical Pollution in
- Authors: M. Pallottini; D. Cappelletti, A. Fabrizi, E. Gaino, E. Goretti, R. Selvaggi, R. Céréghino
Abstract: Both physical–chemical and biological indicators are used to assess the ecological health of ecosystems. The functional trait composition of communities has the potential to predict the impact of environmental change on ecosystems, yet, we miss evidence that information on pollution can be used to forecast the functional responses of freshwater communities. We used chemical and ecological data collected in the Nestore river basin (Central Italy) to test whether (i) there are generalities in the response of macroinvertebrate functional diversity to river pollution; (ii) water pollution filters certain functional traits and (iii) traits do better than chemical analyses at revealing ecological stress in rivers. Due to interactions with hydrology, chemical variables showed higher seasonal variation at impacted sites, so occasional water samples represented snapshots. Functional traits did well at detecting water pollution by various chemicals, and there was a clear shift of trait combinations from unimpacted to impacted sites. Anthropogenic disturbances homogenized benthic communities in terms of taxonomic and functional composition, both in space (impacted sites) and time (seasons). Traits related to feeding habits (mainly reliance on fine particulate organic matter) and tolerance to organic pollution were prevalent at impacted reaches, and functional trait compositions were more stable than water chemistry over seasons because they integrate environmental conditions over longer time periods. Functional traits can play a relevant role in the bioassessment of polluted river ecosystems, even under low to moderate disturbance. Trait-based assessment can be complemented by chemical analyses, notably at highly polluted sites where biological diversity drops to its lowest levels. Copyright © 2016 John Wiley & Sons, Ltd.
- Factors Influencing Movements of Two Migratory Fishes within the Tailrace
of a Large Neotropical Dam and their Implications for Hydropower Impacts
- Authors: F. M. Suzuki; J. B. Dunham, L. G. M. Silva, C. B. M. Alves, P. S. Pompeu
Abstract: Fish attempting to move upstream through hydroelectric dams can be trapped and killed in turbines. Understanding fish movement patterns can provide useful insights for how to manage dam operations to minimize fish kill in turbines. We evaluated the movements of two migratory fish (Curimba—Prochilodus argenteus and Mandi—Pimelodus maculatus) using acoustic telemetry in the tailrace of Três Marias Dam (São Francisco River, Brazil) from 31 October 2011 to 16 February 2012. The majority of tagged fish left the tailrace in less than one week; however, some individuals returned, performing several visits to the tailrace. Mandi remained longer in the tailrace than Curimba. The number of visits was influenced by diel period, turbine and spillway discharge. Although the diel period was the only important contributor to the visits performed by Curimba, the movements of Mandi were significantly influenced by three factors. We found that whereas Curimba was predominantly diurnal, Mandi showed nocturnal habits. Additionally, visits of Mandi were significantly greater during higher turbine and spillway discharge. We discuss the implications of these results for understanding fish movements in the Três Marias Dam tailrace and their potential implications for adapting hydroelectric operations to minimize fish kills. Copyright © 2016 John Wiley & Sons, Ltd.
- Long-term Hydrologic Variability in a Large Subtropical Floodplain River:
Effects on Commercial Fisheries
- Authors: A. P. Rabuffetti; K. Górski, L. A. Espínola, E. Abrial, M. L. Amsler, A. R. Paira
Abstract: We analysed the effects of decadal and annual hydrologic fluctuations on freshwater fisheries catches in the Middle Paraná River for a period of six decades from the 1930s to the 1980s. The climatic fluctuations in this period strongly affected the hydrology of the Middle Paraná River and the characteristics of its flow regime. The magnitude of floods as well as maximum, minimum and mean water levels increased progressively from 1930s until the 1980s concomitantly with increasing frequency and intensity of El Niño Southern Oscillation events that resulted in differentiation of distinct hydrological periods. The flood pulses were significantly more frequent and of greater magnitudes during the 1970s and 1980s. These large floods resulted in increased commercial fish catches in the 1980s, possibly because of enhanced recruitment. Specifically, large floods increased the commercial fish catches 2 years later. This effect was stronger for species that use floodplain habitats as areas of reproduction and larval nurseries, such as Prochilodus lineatus. We conclude that the natural flow regime of the Paraná River and perhaps other large subtropical rivers must be preserved in order to sustain their productive fisheries. Copyright © 2016 John Wiley & Sons, Ltd.
- Evaluation of Central Valley Spring-Run Chinook Salmon Passage Through
Lower Butte Creek Using Hydraulic Modelling Techniques
- Authors: W. R. Cowan; D. E. Rankin, M. Gard
Abstract: River2D was used to develop a hydraulic model of an upstream passage impediment for adult spring-run Chinook salmon (Oncorhynchus tshawytscha) on Butte Creek, Tehama County, California. Topographic data were collected by using a total station, survey-grade real-time kinematic global positioning system, and terrestrial light detection and ranging. Stage-discharge relationships were developed at the upstream and downstream ends of the site to use as boundary conditions and to calibrate the 2D model. A pressure transducer was installed at the downstream boundary of the site to provide a time series of flow and water temperatures. Parameters of the hydraulic model were examined to assess upstream passage including minimum thalweg depth along the least width-limiting pathway, velocity, and water surface elevation above and below a jump, and flow partitioning between a split in the main flow paths through the site. The results of the River2D model were used to identify flow levels that met the minimum depth and width thresholds needed for adult spring-run Chinook salmon (SRCS) to migrate upstream through the study reach. A minimum passage depth criterion of 0.27 m was used for adult SRCS. Site-specific passage width criteria were derived from the literature for the study site and ranged from 0.3 to 0.9 m. Model results indicated that a flow of 3.40 cms met the depth criterion and the lower bound of the width criterion. A flow level of 6.8 cms met the depth criterion and the upper bound of the width criterion. Data from the VAKI Riverwatcher fish passage counting device installed just upstream of the study site were related to the stage/passage limiting width and water temperature monitoring data. The monitoring data and results of the predictive modelling will be used by the California Department of Fish and Wildlife to recommend flow criteria that protect migrating adult SRCS. Copyright © 2016 John Wiley & Sons, Ltd.
- Block Ramps in Curved Rivers: Morphology Analysis and Prototype Data
Supported Design Criteria for Mild Bed Slopes
- Authors: S. Pagliara; A. Radecki-Pawlik, M. Palermo, K. Plesiński
Abstract: Eco-friendly river restoration structures are a valid solution for river training projects. Among this structure typology, block ramps have been successfully tested to solve problems related to river sediment control, bed stabilization and energy dissipation. Despite the conspicuous literature dealing with block ramps design in straight rivers, there are no studies analysing the erosive process occurring in the stilling basin downstream of a block ramp in a curved river bend. Therefore, this paper represents the first systematic analysis of their behaviour and of the resulting downstream equilibrium morphology in such geometric configuration. A dedicated model was built to simulate a wide range of hydraulic conditions. Experimental data analysis allowed describing the erosion dynamics occurring in the stilling basin and, at the same time, to derive a useful design relationship by which it is possible to estimate the maximum scour depth. Furthermore, the model results were successfully validated by using field measurements collected in the Porębianka River (Poland). Both field data and laboratory experimental results allowed furnishing a comprehensive description of the scour phenomenon. The proposed relationship represents the first trustable and valid tool for hydraulic design of such structure typology in curved rivers. Copyright © 2016 John Wiley & Sons, Ltd.
- Dissolved Oxygen Relationships of Under-Ice Water Column and Pore Water
Habitat: Implications for Environmental Guidelines
- Authors: J. M. Culp; E. Luiker, N. E. Glozier, M. Meding, D. Halliwell, F. J. Wrona
Abstract: Substantial reductions in dissolved oxygen concentration in freshwaters can negatively affect aquatic biota. Thus, existing regulatory criteria are designed to avoid environmental conditions that cause acute lethality, thereby reducing the likelihood of biological impairment. In North America, dissolved oxygen (DO) guidelines for protecting aquatic life assume that pore water and water column DO are correlated, with pore water values expected to be on average ≤3 mg/L below water column values. Our study assessed the validity of this assumption during the winter period of ice cover in a large, northern river ecosystem (Wapiti River, Alberta, Canada). We investigated the relationship between water column and pore water DO concentrations and examined whether this relationship was affected by industrial and municipal effluents. Water column DO fell from near saturation during open water periods to 80–84% under winter ice cover. DO concentrations in the pore water were significantly lower than in the water column at reference and effluent-exposed sampling sites. Pore water DO values ranged widely from 0.27 to 13.28 mg/L. In contrast, water column DO concentrations (10.25–13.60 mg/L) were more narrowly distributed over the same period. Indeed, differences between winter pore water and water column DO were often as large as 9–12 mg/L and, notably, were significantly greater than the 3 mg/L difference upon which North American guidelines are based. Consequently, under-ice DO concentrations of river pore water could not be accurately predicted from water column DO alone. Risk factors that may increase the potential for pore water DO to be more than 3 mg/L lower than water column values include the input of oxygen poor groundwater, infilling of the streambed with small inorganic and organic particles, water exchange rates between the water column and the streambed and effluent discharges that raise nutrient concentrations and biochemical oxygen demand. Given that low pore water DO was evident even in undeveloped reference sites, future work must establish the ecological relevance of chronic exposure to low, pore water DO and its impact on river biota. © 2016 Environment and Climate Change Canada. River Research Application © 2016 John Wiley & Sons, Ltd.
- A Comparison of Metabolic Rates in Off-Channel Habitats of the Middle
- Authors: M. J. Sobotka; Q. E. Phelps
Abstract: Autochthonous material has been found to be an important base in large river food webs. However, a spatial understanding of primary production in large rivers is lacking. We modeled primary productivity and community respiration (CR) during a low water period in two types of off-channel habitat present in the Middle Mississippi River, side channels and wing dike fields. Wing dike fields are constantly connected to the main channel and are well mixed along most of their length, while side channels are typically connected only at the top and mouth. Gross primary production (GPP) in wing dike fields ranged from 0.0 to 8.9 g O2 m−2 D−1 and in side channels GPP ranged from 0.4 to 33.5 g O2 m−2 D−1. Both habitat types experienced periods of positive net ecosystem production (NEP) especially in the late summer and early fall. Correlations between metabolic rates and ecosystem characteristics differed between habitat types. Discharge was negatively correlated to NEP in wing dike fields but was not associated with metabolic rates in side channels. Light was positively correlated with GPP and CR at both site types and with NEP in side channels. These areas are protected from high velocity and likely experience greater light penetration, allowing more photosynthesis to take place especially during low water periods. This study demonstrates the potential for high productivity in off-channel habitats that are permanently connected to the main channel. Copyright © 2016 John Wiley & Sons, Ltd.
- Benchmarking Fluvial Dynamics for Process-Based River Restoration: the
Upper Rhine River (1816–2014)
- Authors: M. Diaz-Redondo; G. Egger, M. Marchamalo, S. Hohensinner, E. Dister
Abstract: Multi-temporal analysis of river-floodplain processes is a key tool for the identification of reference conditions or benchmarks and for the evaluation of deviations or deficits as a basis for process-based river restoration in large modified rivers. This study developed a methodology for benchmarking fluvial processes at river segment level, focusing on those interrelations between morphodynamics (aggradation, erosion, channel shift) and vegetation succession (initial, colonization, transition) that condition habitat structure. Habitat maps of the free-flowing Upper Rhine River downstream from Iffezheim dam (France–Germany border) were intersected with a geographic information system-based approach. Patches showing trajectories of anthropization, changeless, progression and regression allowed for the identification of natural and human-induced processes over almost 200 years. Before channelization, the riverine system was characterized by a shifting habitat mosaic with natural heterogeneity, high degree of surface water connectivity and equilibrium between progression and regression processes. On the other hand, the following 175 years of human interventions led to severe biogeomorphologic deficits evidenced by loss of natural processes and habitat heterogeneity, hydrological disconnection between the river and its floodplain and imbalance of progression versus regression dynamics. The main driving forces of change are found in hydromorphological impacts (channelization, regulation and hydropower plant construction). Regression processes are now almost absent and have to be the objective of process-based river restoration measures for the studied river-floodplain system. A sustainable view on water management and river restoration should aim at a more resilient riverine system by balancing the recovery of natural processes with societal needs. Copyright © 2016 John Wiley & Sons, Ltd.
- The Interplay between Environmental Conditions and Filamentous Algae Mat
Formation in Two Agricultural Influenced South African Rivers
- Authors: P. J. Oberholster; V. S. Somerset, J. C. Truter, A.-M. Botha
Abstract: The regulation of nutrient inputs into rivers dominated by agriculture land use activities is an important aspect of ecological resilience of aquatic systems and the management of river eutrophication. The overabundance of benthic filamentous algae mats in river systems due to nutrient enrichment can modify the habitats of macroinvertebrate and fish communities as well as clogging irrigation crop sprayers of downstream water users. The current study examined over a period of 2 years (2013–2014) the interplay between physical and chemical river characteristics and epilithic filamentous algae biomass in two South African agricultural influenced rivers. The study area consisted of the Touw and Duiwe Rivers, which run into a proclaimed Ramsar site, namely, the Wilderness Lake System. A strong positive correlation was observed between the maximum filamentous algae biomass (97 chl-a mg m−2) observed during the dry season and the average water column alkalinity >30 mg l−1. The benthic trophic status of the nine sampling sites during the dry seasons indicated the highest benthic algae biomass with mesotrophic (1.7–21 chl-a mg m−2) to hypertrophic (>84 chl-a mg m−2) conditions. During the dry season, only three sampling sites were below the suggested guideline value (35 µg l−1) for total phosphorus (TP), while four sampling sites were below the total nitrogen guideline of 252 µg l−1. In the wet season, two sites were below TP values with five sites below total nitrogen guideline values. From the data gathered, it was evident that water column alkalinity and hardness were the main drivers for the formation or absence of benthic filamentous algae mats in the two river systems and that nitrogen and/or phosphorus concentrations was overshadowed by the physical and chemical characteristics of the river systems at certain sites. Nutrient results for the river bottom sediments revealed that the sediment qualities were variable at the different sampling sites, but more specifically along the longitudinal paths of flow. It was apparent that the high TP concentrations in the water column and bottom sediment, which were lowest during the dry season, were associated with the highest epilithic filamentous algae mat formation. The outcome of the current study shows that a more holistic approach must be followed for the development of future eutrophication guidelines and nutrient thresholds in South African rivers influenced by agriculture land use activities. Copyright © 2016 John Wiley & Sons, Ltd.
- Chemical and Isotopic Tracer Evaluation of Water Mixing and Evaporation in
a Dammed Texas River During Drought
- Authors: A. A. Vanplantinga; E. L. Grossman, E. B. Roark
Abstract: The interaction between drought and river regulation is monitored to better understand river flow mixing, evaporation and surface-groundwater exchange in changing regional climates and in increasingly regulated waterways. This study compared Brazos River stable isotope (δ18O and δD) and electrical conductivity values with reservoir, creek and aquifer samples in the Brazos watershed, the largest watershed in Texas. The combination of tributaries, rainfall and the Brazos River Alluvium Aquifer, on the one hand, and the Lake Whitney reservoir, on the other hand, represent endmembers of dilute run-off water and evaporated saline water, respectively. A simple isotope mixing model that uses monthly river discharge, Lake Whitney discharge, historical monthly precipitation δ18O and pan evaporation accurately reconstructs river δ18O (±0.5‰ on average). Data and isotope balance modelling support continued evaporation of 18O-enriched Lake Whitney water as it flows downstream, although the most evaporation took place in Lake Whitney. The difference between river and precipitation δ18O, or Δ18ORIV-PPT, here a measurement of degree of evaporation, ranged from −0.1‰ for a small creek, to 1.7‰ for the Brazos River, to at least 2.7‰ in Lake Whitney. This study indicates that drought in regulated rivers may enhance reservoir discharge dominance in river flows during peak drought conditions when combined run-off and baseflow dominance would be expected in a similar undammed river. Copyright © 2016 John Wiley & Sons, Ltd.
- Quantifying Submerged Deposited Fine Sediments in Rivers and Streams Using
Digital Image Analysis
- Authors: M. D. Turley; G. S. Bilotta, G. Arbociute, R. P. Chadd, C. A. Extence, R. E. Brazier
Abstract: Deposited fine sediment is an essential component of freshwater ecosystems. Nonetheless, anthropogenic activities can modify natural fine sediment levels, impacting the physical, chemical and biological characteristics of these ecosystems. An ability to quantify deposited fine sediment is critical to understanding its impacts and successfully managing the anthropogenic activities that are responsible for modifying it. One widely used method, the visual estimate technique, relies on subjective estimates of particle size and percentage cover. In this paper, we present two novel alternative approaches, based on non-automated digital image analysis (DIA), which are designed to reduce the subjectivity of submerged and surficial fine sediment estimates, and provide a verifiable record of the conditions at the time of sampling. The DIA methods were tested across five systematically selected, contrasting temperate stream and river typologies, over three seasons of monitoring. The resultant sediment metrics were strongly, positively correlated with visual estimates (rs = 0.90, and rs = 0.82, p
- The Importance of Shallow-Low Velocity Habitats to Juvenile Fish in the
Middle Mississippi River
- Authors: S. A. Love; Q. E. Phelps, S. J. Tripp, D. P. Herzog
Abstract: Habitat management is a crucial aspect of fisheries management. Without knowledge of habitat associations, fisheries scientists are unable to effectively make habitat conservation or restoration recommendations. This becomes especially prominent when trying to manage commercially harvested populations and protect threatened or endangered species. To determine juvenile fishes habitat associations in the Middle Mississippi River, we analysed mini-trawl catch data of six common juvenile fish species: blue catfish (Ictalurus furcatus), channel catfish (Ictalurus punctatus), channel shiner (Notropis wickliffi), freshwater drum (Aplodinotus grunniens), paddlefish (Polyodon spathula), and shovelnose sturgeon (Scaphirhynchus platorynchus). Overall, we conducted 2251 mini-trawl sampling efforts between 2002 and 2013, resulting in the capture of 23,742 target specimens. Catch per unit effort was evaluated by structural habitat (i.e. velocity, depth, and substrate). Overall, these data suggest that juvenile fish species are more prevalent in shallow water and slower velocities. Ultimately the information garnered during this evaluation should be incorporated when considering habitat modifications, especially those modifications that impact the availability of shallow-low velocity habitats. Copyright © 2016 John Wiley & Sons, Ltd.
- A Fuzzy Rule-based Model for the Assessment of Macrobenthic Habitats under
- Authors: M. Schneider; I. Kopecki, J. Tuhtan, J. F. Sauterleute, P. Zinke, T. H. Bakken, T. Zakowski, S. Merigoux
Abstract: Hydropeaking presents one of the large impacts on river ecology and is gaining importance because of an increasinlgy volatile energy market with high portions of new renewable energies dependent on local climate conditions. This study presents the application of a fuzzy logic model for the investigation of macrobenthic habitats under hydropeaking conditions in the Norwegian river Surna. Preference data of the three taxa Baetis rhodani, Hydroptila spp. and Allogamus auricollis with distinctively different habitat requirements related to near-bottom flow forces (high/low forces, and narrow range) are used. These data are transferred into the multivariate fuzzy rule-based physical habitat model Computer Aided Simulation of Instream flow and Riparia in order to integrate water depth and river bed substrate as additional parameters. Permanently available habitats (persistent habitats) are assessed for different scenarios of hydropeaking operation. It is found that the amount of persistently high-quality habitat is closely related to the size and range of fluctuations in hydraulic conditions occuring during hydropeaking events. Effects are much more distinct for species with a narrow range of hydraulic preference. The integration of water depth in the simulations has a noticable impact on the amount and quality of predicted habitats. Substrate conditions in the investigation site are homogeneous and, in the specific case considered, do not have a significant impact. The study suggests persistent habitats as a suitable indicator of hydropeaking impact on organisms with low mobility. The persistent habitat approach takes into account that organisms with a low mobility and a distinct range of tolerance related to hydraulic stress tend to settle in areas with permanently stable conditions. Multivariate aspects are accounted through the fuzzy rule-based approach and do clearly affect habitat predictions. Habitat requirements of species particularly sensitive to hydropeaking are proposed for the investigation and application in the future. Copyright © 2016 John Wiley & Sons, Ltd.
- Flood Inundation Modelling for Mid-Lower Brisbane Estuary
- Authors: X. Liu; S. Lim
Abstract: This study utilizes a two-dimensional hydrodynamic model to calibrate and validate an inundation model for the Brisbane River estuary in Queensland, Australia. The bathymetry data used in the hydraulic model are derived from one arc second (1 s) shuttle radar topography mission digital elevation model, and the two-dimensional hydraulic model is parameterized using the generated bathymetry with four open boundaries with water level observations and roughness coefficients. The calibration performance is evaluated by comparing the simulated results with the digitized records during the January 2013 flood event (a low magnitude event) at three gauging stations. The calibrated model is validated with water level data and available discharge data during the January 2011 flood (a large magnitude event) at four gauging stations located along the Brisbane River. Different performance indices are applied to demonstrate that the developed model performs well during calibration and validation. A sensitivity analysis is presented to assess the influence of riverbed elevation changes on the model because the main uncertainty of the model is the bathymetry data. The proposed model with the shuttle radar topography mission digital elevation model-derived riverbed elevation for the Brisbane estuary is able to predict the flood inundation extent at an accuracy of 66.9% which is higher than or comparable with the accuracies of the existing studies. However, it is expected that the accuracy will increase if some improved bathymetry data become available in the future. Copyright © 2016 John Wiley & Sons, Ltd.
- Socioeconomic Value(s) of Restoring Environmental Flows: Systematic Review
and Guidance for Assessment
- Authors: D. Jorda-Capdevila; B. Rodríguez-Labajos
Abstract: The preservation of instream flows entails multiple benefits not only for river ecosystems but also for human well-being. Benefits of marketed goods and services provided by water withdrawals such as irrigation, water supply and hydropower production are well-known. Others, such as recreational, aesthetic, cultural and existence values of a well-preserved river flows are less studied. There is an increasing interest of policy makers to understand the benefits of costly river ecosystem restoration measures. Moreover, disregarding such benefits may turn into inter-stakeholder conflicts.This paper reviews empirically-based literature assessing environmental flows restoration/conservation. Thus, it offers the state-of-the-art on three aspects: 1) what motivations drive the socioeconomic evaluation of instream flows (policies and alternative instream flow regimes); 2) what values and benefits are associated with instream flows (e.g. the sheer existence of a well-preserved river, productive assets and cultural attributes); and 3) what methods are employed to undertake such assessments (e.g. scenario development, monetary and non-monetary valuations, and stakeholders engagement).Building on this, we propose a methodological framework for case-specific assessments of the restoration of environmental flows. This proposal combines increased stakeholder participation, better understanding of ecosystem functioning, awareness of the plurality of values and an accurate choice of valuation methods. Copyright © 2016 John Wiley & Sons, Ltd.
- Hydrogeochemistry, Isotopic Composition and Water Age in the Hydrologic
System of a Large Catchment within a Plain Humid Environment (Argentine
Pampas): Quequén Grande River, Argentina
- Authors: D. E. Martínez; O. M. Quiroz Londoño, D. K. Solomon, C. Dapeña, H. E. Massone, M. A. Benavente, H. O. Panarello
Abstract: The Quequén Grande River (QGR) is a large catchment (10 000 km2) in the Pampa Plain in Argentina. From November 2004 to April 2013, a hydrochemical and stable isotopes monitoring program was conducted, which included three sampling stations of monthly composite precipitation, weekly samples in two sites along the river and several groundwater samples.A standard data interpretation was initially performed applying standard statistics, Piper diagrams and δ18O versus δ2H diagrams. The time evolution of the values of δ18O in precipitation and streamwater were also determined.The integration of hydrogeochemistry and stable isotopes data indicates the existence of three main components of streamflow: (i) baseflow characterized by electrical conductivity (EC) from 1200 to 1800 µs/cm and an isotope composition quite constant around δ18O −5.3‰ and δ2H −33.8‰. Water age for groundwater contribution is typically around 30 to 40 years using chlorofluorocarbons; (ii) direct runoff composed of channel interception and overland flow, which is of low EC in the order of 50 to 100 µs/cm, and a highly variable isotopic composition; and (iii) translatory flow (pre-event water that is stored within the subsoil) with an intermediate EC and isotopic composition close to that of the weighted average composition of precipitation.The hydrochemical and stable isotopic data allow the differentiation between baseflow and direct runoff. In addition to this, chlorofluorocarbon dating is a useful tool in assessing the dominance of baseflow in a stream. The data lead to a conceptual model in which an intermediate flow system, with mean residence time (MRT) of around 35 years, discharges into the drainage network. A regional flow system (MRT > 50 years) discharges to the ocean. It is concluded that in this large plain catchment streamflow separation, only two components can be applied in: (i) short storm precipitation events having a high sampling frequency and (ii) during long dry periods when pre-event soil water is not released. Copyright © 2016 John Wiley & Sons, Ltd.
- Integrating Hydrological Modelling and Ecosystem Functioning for
Environmental Flows in Climate Change Scenarios in the Zambezi River
(Zambezi Region, Namibia)
- Authors: F. Martínez-Capel; L. García-López, M. Beyer
Abstract: The Zambezi-Chobe wetlands in Namibia are of great international importance for trans-boundary water management because of their remarkable ecological characteristics and the variety and magnitude of the ecosystem services provided. The main objective of this study is to establish the hydro-ecological baseline for the application of environmental flow regimes (EFR). The specific objectives are: (i) the assessment of environmental flow components (EFC) in the current near-natural hydrological conditions; (ii) the generation of future scenarios for climatic and socioeconomic changes; (iii) the estimation of the area–duration curves and estimated annual habitat during the inundation of the critical habitats for fisheries (mulapos), under the existing conditions and future scenarios; and (iv) to provide a framework for the future application of EFRs, based on hydrological and ecological processes. To make a sound analysis of the ecological implications, first we develop a conceptual framework of the linkages between the hydrological and biological processes concerning fish communities, because of the critical role of fisheries in the region. The EFCs in near-natural hydrological conditions provide the basis for developing interim EFRs in the region, within the framework of an adaptive management of water resources. The future scenarios indicate a mitigation of the flow variability; and, in the worst-case scenario, the reduction of the maximum flow and inundated area of the mulapos would result in a reduction of the estimated annual habitat of 22%. This means a reduction in the spawning habitats for quiet-water species, in the food resources for fry and juvenile fish and a consequent reduction in fish stocks. Furthermore, the habitat loss during low events is similar and greater under both scenarios, at ca. 35%. Here we corroborate that the EFCs and their variability may become the building blocks of flow-ecology models that lead to environmental flow recommendations, monitoring and research programmes and flow protection activities. Copyright © 2016 John Wiley & Sons, Ltd.
- A Comparison of Main and Side Channel Physical and Water Quality Metrics
and Habitat Complexity in the Middle Mississippi River
- Authors: M. J. Sobotka; Q. E. Phelps
Abstract: Worldwide large rivers have been severely modified by human intervention. Many modifications result in disconnection of the river from floodplain and off-channel habitats generally characterized by lower velocities and Copyright © 2016 John Wiley & Sons, Ltd. shallower depths relative to the main channel, conditions vital to many organisms. Extensive levees on the Middle Mississippi River (MMR) have cut off backwater systems and disconnected the river from 80% of its floodplain. However, the system is characterized by large side channels associated with islands. We examined a long term data set for differences in physical (e.g. depth and velocity) and water quality metrics (e.g. temperature, suspended solids, dissolved oxygen, chlorophyll, % organic matter) between the main and side channels of a 128-km reach of the MMR. We compared variability between main and side channels using the coefficient of variation (COV). All metrics differed between habitats. Side channels were shallower with lower velocities and had greater mean and COV of % organic matter and more variable dissolved oxygen concentrations. Velocity, temperature, and suspended solids were similar in the spring. COVs were lowest in both habitats during the spring for all metrics except temperature and DO. Resource management in the MMR tends to focus on maintaining existing side channels because of the difficulty of working in the heavily used navigation channel. This study shows that these actions protect areas that function differently than the main channel for most of the year. However, our results also highlight the need for restoration activities aimed at restoring floodplain connectivity, especially during the spring. Copyright © 2016 John Wiley & Sons, Ltd.
- Screening the Suitability of Levee Protected Areas for Strategic
Floodplain Reconnection Along the LaGrange Segment of the Illinois River,
- Authors: J. W. F. Remo; R. J. Guida, S. Secchi
Abstract: Levee-protected floodplains along the 125-km LaGrange Segment (LGS) of the Illinois River were screened for their abiotic suitability for alternative ecosystem services (ESs), including wetland creation, habitat, floodwater denitrification and flood-tolerant agriculture. The suitability framework developed for this study builds upon the Land Capability Potential Index and is informed by the current understanding of the linkages between river hydrology, hydraulics, floodplain soils, floodplain vegetation and floodplain nutrient cycling. In addition to screening these floodplain areas for alternative ESs, we demonstrate how this framework can be combined with economic assessments of current floodplain services to inform how strategic floodplain reconnection (i.e. restoration of hydrologic linkages between river and floodplain for the purpose of flood mitigation and provisioning of alternative ESs) could be used to work towards sustainable floodplain management. Results show that ESs increase with upstream distance from the LaGrange Lock and Dam. This is attributed to the operation of the lock and dam generating a water level that would result in the inundation of a substantial portion of floodplain (>70 km2) up to ˜60 km upstream if the levees were to be removed or set back. Comparison of the profits from current floodplain agriculture with the potential profits of flood-tolerant agriculture suggests that overcoming the economic costs of floodplain reconnection within the LGS will likely require both conversion of reconnected floodplain lands to flood-tolerant agriculture and payments for ESs. Copyright © 2016 John Wiley & Sons, Ltd.
- Assessment of the Entering Stock, Migration Dynamics and Fish Pass
Fidelity of European Eel in the Belgian Meuse River
- Authors: B. Nzau Matondo; J. P. Benitez, A. Dierckx, J. C. Philippart, M. Ovidio
Abstract: Migration dynamics of incoming eels in Belgium via Lixhe in the Meuse River were investigated using two fish passes with different configurations—net traps and automatic detection stations—as tools to distinguish resident and migrating eels. From April to September 2013, 435 eels (P50 length, 403 mm; range, 196–836 mm) were caught (daily maxima catch, 90 eels per day), 90% between 13 June and 1 August (50 days) and P50 on 19 July. Eels migrated mostly at 19–26 °C (P50, 24.4 °C), river discharge 65–314 m3 s−1 (P50, 84 m3 s−1), during the dark at 00:00–05:00 h and during both the waxing and waning phases of moonlight. From 396 eels tagged and released 0.3 km downstream of the Lixhe dam, 6.8% of them were recaptured, and 37.4% were detected. Migration flux was estimated at 7184 eels (0.863 t) using the mark-recapture method and decreased to 1156 eels (0.139 t) using automatic transponder detection. Most eels probably migrated through a sluice located downstream of Lixhe to reach the upper Meuse via the Albert Canal. Eels moved almost independently to the configuration of the fish passes and their location, but most eels displayed fidelity to the fish pass where they were captured. Migrant eels showed a wide range of size and life stages, with a higher proportion of eels (80%) belonging to the yellow eel stage. A lower proportion of eels (6%) had a larger size and presented an advanced continental silvering process corresponding to the migrating stage before their transatlantic migration. Copyright © 2016 John Wiley & Sons, Ltd.
- Fluvial Corridor Changes Over Time in Regulated and Non-Regulated Rivers
(Upper Esla River, NW Spain)
- Authors: V Martínez-Fernández; M González del Tánago, J Maroto, D. García de Jalón
Abstract: Over the last decades, rivers and fluvial corridors have been noticeably modified from their natural conditions. In general, damming and other in-channel human interventions have been traditionally considered as the main drivers of change. However, recent studies highlight the influence of climate, hillslope and floodplain cover changes over fluvial corridor dynamics. The present study illustrates the channel morphology and riparian vegetation responses observed in three gravel bed rivers located in the Upper Esla River, north-west of Spain. The entire study catchment was exposed to afforestation changes and farmland abandonment during the last decades, and two of the rivers are regulated by large dams. Analysis of historical orthophotos at different periods between 1956 and 2011 allowed quantifying channel narrowing, reduction of braiding index and vegetation encroachment along the three rivers. Field reconnaissance of landforms and vegetation structure along transects showed significant differences in species composition and age structure between the non-regulated reach, where recruitment of Salicacea pioneer species existed, and the regulated reaches where mature and late-seral species were much more abundant. These responses were consistent with reductions in mean annual discharge in all rivers and with flood disturbance decrease and summer minimum flow increase that were observed in the regulated rivers. Copyright © 2016 John Wiley & Sons, Ltd.
- Informing Watershed Connectivity Barrier Prioritization Decisions: A
- Authors: S. K. McKay; A. R. Cooper, M. W. Diebel, D. Elkins, G. Oldford, C. Roghair, D. Wieferich
Abstract: Water resources and transportation infrastructure such as dams and culverts provide countless socio-economic benefits; however, this infrastructure can also disconnect the movement of organisms, sediment, and water through river ecosystems. Trade-offs associated with these competing costs and benefits occur globally, with applications in barrier addition (e.g. dam and road construction), reengineering (e.g. culvert repair), and removal (e.g. dam removal and aging infrastructure). Barrier prioritization provides a unique opportunity to: (i) restore and reconnect potentially large habitat patches quickly and effectively and (ii) avoid impacts prior to occurrence in line with the mitigation hierarchy (i.e. avoid then minimize then mitigate). This paper synthesizes 46 watershed-scale barrier planning studies and presents a procedure to guide barrier prioritization associated with connectivity for aquatic organisms. We focus on practical issues informing prioritization studies such as available data sets, methods, techniques, and tools. We conclude with a discussion of emerging trends and issues in barrier prioritization and key opportunities for enhancing the body of knowledge. Copyright © 2016 John Wiley & Sons, Ltd.
- An Approach to Simulate Interstitial Habitat Conditions During the
Incubation Phase of Gravel-Spawning Fish
- Authors: M. Noack; J. Ortlepp, S. Wieprecht
Abstract: The incubation period represents an important development phase for successful reproduction of gravel-spawning fish, whereby colmation processes can affect the quality of the interstitial habitat. From a sedimentary perspective, the infiltration and accumulation of fine sediments can result in a reduction of the pore space and limit the transport of oxygen-rich surface water in the interstitials of riverbeds. From a biogeochemical perspective, the increased surface area for microbial growth can lead to an increase of respiration rates, which additionally limits the oxygen supply. The assessment and prediction of such processes on interstitial habitat quality represents a challenging task given their complex dynamic interacting processes and their high spatio-temporal variability. This study presents a new habitat-based modelling approach, which simulates interstitial habitat suitability (IHS) to evaluate dynamically the quality of interstitial habitat conditions during incubation. For this purpose, three key parameters (hydraulic conductivity, interstitial temperature and hyporheic respiration) are linked to the habitat requirements of different developmental stages during the incubation period (egg, hatching, larvae) via a multivariate fuzzy approach. The proposed modelling concept has been developed on the River Spoel in Switzerland, whereby results of a numerical 3D sediment transport model, together with supplementary measurements, deliver the spatio-temporal variations of the required input data. The fuzzy approach provides results in form of maps and time series of IHS values to allow for an identification of abiotic bottlenecks during the incubation period. Hence, this approach represents a significant contribution for the restoration of reproduction areas of gravel-spawning fish. Copyright © 2016 John Wiley & Sons, Ltd.
- Regional Statistical and Precipitation–Runoff Modelling for Ecological
Applications: Prediction of Hourly Streamflow in Regulated Rivers and
- Authors: Teklu T. Hailegeorgis; K. Alfredsen
Abstract: Prediction of natural streamflow in regulated rivers for derivation of ecologically relevant streamflow metrics (ERSFMs) and prediction in ungauged basins (PUB) are important in management of water resources. However, specific studies on comparison of methods for predicting hourly flow regime relevant to ecological study in regulated (hydropeaking) rivers are rare in literature. Therefore, using catchments in mid Norway, we performed comparative evaluation of prediction of hourly streamflow series and flow duration curves (FDCs) in ungauged basins. We developed a regional regression model based on relationships among streamflow percentiles and drainage areas and performed a regional calibration of a streamflow recession based precipitation–runoff (P–R) model.A leave one out cross-validation procedure was used to evaluate the regional models. The results indicate that the regional regression model with transferring of streamflow information based on the nearest neighbour performed better than both transferring optimal parameters from local calibration and regional parameter sets corresponding to maximum regional weighted average Nash–Sutcliffe efficiency of the P–R model (NSEMRWA). We also evaluated the models based on prediction of some environmental indices: the daily range, daily standard deviation, flashiness, maximum ramping rate, number of rise and falls and daily flow changes. However, both modelling strategies predicted hourly streamflow indices well and appeared stable over most indices while the largest differences occurred in the rise and fall counts.The models were further applied for prediction of the natural streamflow time series at Sokna hydropeaking plant. The observed hydrograph exhibits continuous sudden fluctuations while the predicted natural flow hydrograph exhibits smooth pattern. The within a year FDCs for observed flow exhibits sharp transitions from high to low flows. There is clear differences between the environmental indices obtained for the observed and the modelled data series, with the general observation that the NSEMRWA computing a smaller variability than the regression model. Copyright © 2016 John Wiley & Sons, Ltd.
- Time and Intensity Weighted Indices of Fluvial Processes: a Case Study
from the Kootenai River, USA
- Authors: G. Egger; E. Politti, E. Lautsch, R. M. Benjankar, S. B. Rood
Abstract: Within riparian landscapes, river flows and stages determine habitat gradients from less to more dynamic, and these support different plant species and their life history stages that are adapted to specific positions along these gradients. The gradients are characterized by physical processes that vary in magnitude and duration, and these shape the riparian vegetation communities. Consequently, natural riparian ecosystems are very dynamic, and the river disturbance regime is essential for sustaining ecosystem health. However, although the importance of disturbance is well accepted, disturbance regimes are poorly understood. This study was undertaken to develop indices capable of characterizing riparian habitats by considering flood magnitude and the elapsed time after flood disturbance, that is, the history that influenced the present vegetation composition. The indices were tested along two reaches of the Kootenai River in Idaho, USA, with braided versus meandering channel forms. The case study spanned a 31-year period and emphasized two major disturbance components, the morphodynamic influence of velocity and shear stress and the flood or inundation duration. Computed indices were tested for consistency and then used to characterize different riparian vegetation development and succession phases. The statistical analysis revealed high correspondence among the calculated indices and differences across the different successional stages and between the two reaches. This demonstrated the utility of the time and intensity weighted indices to analyse the fluvial patterns that support different riparian vegetation communities, and this could be applicable for riparian management, mitigation, conservation and restoration. Copyright © 2016 John Wiley & Sons, Ltd.