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        1 2     

  Subjects -> WATER RESOURCES (Total: 128 journals)
Acta Limnologica Brasiliensia     Open Access   (2 followers)
Advances in Oceanography and Limnology     Partially Free   (9 followers)
Advances in Water Resource and Protection     Open Access   (1 follower)
Advances in Water Resources     Hybrid Journal   (17 followers)
African Journal of Aquatic Science     Hybrid Journal   (13 followers)
Agricultural Water Management     Hybrid Journal   (13 followers)
American Water Works Association     Full-text available via subscription   (13 followers)
Anales de Hidrología Médica     Open Access  
Annals of Warsaw University of Life Sciences - SGGW. Land Reclamation     Open Access   (2 followers)
Annual Review of Marine Science     Full-text available via subscription   (9 followers)
Applied Water Science     Open Access   (5 followers)
Aquacultural Engineering     Hybrid Journal   (7 followers)
Aquaculture     Hybrid Journal   (26 followers)
Aquaculture Research     Hybrid Journal   (21 followers)
Aquatic Conservation Marine and Freshwater Ecosystems     Hybrid Journal   (19 followers)
Aquatic Geochemistry     Hybrid Journal   (1 follower)
Aquatic Living Resources     Hybrid Journal   (11 followers)
Aquatic Procedia     Open Access  
Aquatic Science and Technology     Open Access   (2 followers)
Aquatic Sciences     Hybrid Journal   (10 followers)
Asian Journal of Earth Sciences     Open Access   (16 followers)
Asian Journal of Rural Development     Open Access   (9 followers)
Australian Journal of Water Resources     Full-text available via subscription   (5 followers)
Bubble Science, Engineering & Technology     Hybrid Journal  
Canadian Water Resources Journal     Hybrid Journal   (17 followers)
Civil and Environmental Research     Open Access   (11 followers)
CLEAN - Soil, Air, Water     Hybrid Journal   (14 followers)
Computational Water, Energy, and Environmental Engineering     Open Access   (1 follower)
Continental Journal of Water, Air, and Soil Pollution     Open Access   (6 followers)
Cost Effectiveness and Resource Allocation     Open Access   (3 followers)
Desalination     Hybrid Journal   (9 followers)
Desalination and Water Treatment     Hybrid Journal   (8 followers)
Developments in Water Science     Full-text available via subscription   (6 followers)
Ecological Chemistry and Engineering S     Open Access   (2 followers)
Environmental Toxicology     Hybrid Journal   (8 followers)
EQA - International Journal of Environmental Quality     Open Access   (1 follower)
European journal of water quality - Journal européen d'hydrologie     Full-text available via subscription   (2 followers)
Ground Water Monitoring & Remediation     Hybrid Journal   (8 followers)
Grundwasser     Hybrid Journal  
Human Resources for Health     Open Access   (3 followers)
Hydro Nepal : Journal of Water, Energy and Environment     Open Access   (1 follower)
Hydrology Research     Partially Free   (6 followers)
International Journal of Climatology     Hybrid Journal   (10 followers)
International Journal of Hydrology Science and Technology     Hybrid Journal   (3 followers)
International Journal of Nuclear Desalination     Hybrid Journal   (2 followers)
International Journal of River Basin Management     Hybrid Journal   (1 follower)
International Journal of Salt Lake Research     Hybrid Journal   (2 followers)
International Journal of Waste Resources     Open Access   (3 followers)
International Journal of Water     Hybrid Journal   (10 followers)
International Journal of Water Resources and Environmental Engineering     Open Access  
International Journal of Water Resources Development     Hybrid Journal   (13 followers)
Iranian Journal of Environmental Health Science & Engineering     Open Access   (1 follower)
Irrigation and Drainage     Hybrid Journal   (3 followers)
Irrigation Science     Hybrid Journal   (3 followers)
Journal of Waste Water Treatment & Analysis     Open Access   (10 followers)
Journal of Aquatic Sciences     Full-text available via subscription  
Journal of Contemporary Water Resource & Education     Hybrid Journal   (2 followers)
Journal of Fisheries and Aquatic Science     Open Access   (4 followers)
Journal of Geophysical Research : Oceans     Partially Free   (14 followers)
Journal of Hydro-environment Research     Full-text available via subscription   (6 followers)
Journal of Hydroinformatics     Full-text available via subscription   (1 follower)
Journal of Hydrology (New Zealand)     Full-text available via subscription  
Journal of Hydrology and Hydromechanics     Open Access  
Journal of Hydrometeorology     Full-text available via subscription   (3 followers)
Journal of Limnology     Open Access   (6 followers)
Journal of the American Water Resources Association     Hybrid Journal   (18 followers)
Journal of Water and Climate Change     Partially Free   (22 followers)
Journal of Water and Health     Partially Free   (1 follower)
Journal of Water Chemistry and Technology     Hybrid Journal   (6 followers)
Journal of Water Resource and Hydraulic Engineering     Open Access   (3 followers)
Journal of Water Resource and Protection     Open Access   (5 followers)
Journal of Water Resources Planning and Management     Full-text available via subscription   (22 followers)
Journal of Water Reuse and Desalination     Partially Free   (6 followers)
Journal of Water Supply : Research and Technology - Aqua     Partially Free   (8 followers)
Journal of Water, Sanitation and Hygiene for Development     Open Access   (3 followers)
La Houille Blanche     Full-text available via subscription  
Lake and Reservoir Management     Hybrid Journal   (4 followers)
Lakes & Reservoirs Research & Management     Hybrid Journal   (15 followers)
Large Marine Ecosystems     Full-text available via subscription   (1 follower)
Mangroves and Salt Marshes     Hybrid Journal   (3 followers)
Marine and Freshwater Behaviour and Physiology     Hybrid Journal   (1 follower)
Methods in Oceanography : An International Journal     Hybrid Journal   (1 follower)
New Zealand Journal of Marine and Freshwater Research     Hybrid Journal   (4 followers)
Open Journal of Modern Hydrology     Open Access   (1 follower)
Osterreichische Wasser- und Abfallwirtschaft     Hybrid Journal  
Ozone Science & Engineering     Hybrid Journal   (1 follower)
Paddy and Water Environment     Hybrid Journal   (1 follower)
Research Journal of Environmental Toxicology     Open Access   (2 followers)
Reviews in Aquaculture     Hybrid Journal   (8 followers)
Revue des sciences de l'eau / Journal of Water Science     Full-text available via subscription   (1 follower)
Riparian Ecology and Conservation     Open Access   (3 followers)
River Research and Applications     Hybrid Journal   (5 followers)
River Systems     Full-text available via subscription   (3 followers)
SA Irrigation = SA Besproeiing     Full-text available via subscription  
San Francisco Estuary and Watershed Science     Open Access   (1 follower)
Sciences Eaux & Territoires : la Revue du Cemagref     Open Access   (1 follower)
Scientia Marina     Open Access   (2 followers)
Society & Natural Resources: An International Journal     Hybrid Journal   (9 followers)
Sri Lanka Journal of Aquatic Sciences     Open Access  
Sustainable Technologies, Systems & Policies     Open Access   (8 followers)

        1 2     

River Research and Applications    [7 followers]  Follow    
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1535-1459 - ISSN (Online) 1535-1467
     Published by John Wiley and Sons Homepage  [1594 journals]   [SJR: 0.85]   [H-I: 52]
    • Authors: H. Liu; Y. Ding, M. Li, P. Lin, M. H. Yu, A. P. Shu
      Pages: n/a - n/a
      Abstract: In this study, a two‐dimensional hybrid numerical model for sediment transport based on lattice Boltzmann method and finite difference method is presented. The governing equations for water flow and suspended sediment transport are the shallow water equations and the advection–diffusion equations, respectively. Sediment load is also involved, so that riverbed deformation is numerically simulated. The model is verified by testing transportation of bank‐slump sediment in a sharp bended channel with the comparison to the results of well‐accepted finite volume method, illustrating the effectiveness of the proposed hybrid model. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-01-23T04:04:10.31352-05:0
      DOI: 10.1002/rra.2735
    • Authors: U. Malvadkar; F. Scatena, M. Leon
      Pages: n/a - n/a
      Abstract: Barriers within streams can affect riverine species' ability to access habitats and may reduce their population viability. Connectivity metrics attempt to quantify the impacts of barriers; however, little is known about their functioning when applied to dendritic habitats such as watersheds. Several graph‐theoretic connectivity metrics were calculated on rivers originating in the Luquillo Mountains of Puerto Rico. These metrics were classified into two primary groups: metrics that count weighted paths through the stream network and metrics that predict the flow of organisms through a stream reach. Representative metrics from each of these categories were suggested to model the effects of dams and water intakes, respectively. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-01-21T23:00:58.162407-05:
      DOI: 10.1002/rra.2730
    • Authors: R. Casas‐Mulet; K. Alfredsen, T. Boissy, H. Sundt, N. Rüther
      Pages: n/a - n/a
      Abstract: Fish stranding is a critical issue in rivers with peaking operations. The ability to accurately predict potential stranding areas can become a decisive factor to assess environmental impacts and to plan mitigation measures. The presented work shows that common procedures suggested in the literature in the use of one‐dimensional (1D) models for flood zone mapping are not always applicable to compute stranding areas. Specific and easy‐to‐understand guidance needs to be given for smaller‐scale issues. We provide specific guidelines to accurately predict potential stranding areas in a cost‐effective manner. By analysing four different river morphologies in detail in a peaking river, we find that the optimal geometry effort (number of cross sections) does not necessarily coincide with the maximum and it varies between channel types according to river physical characteristics such as sinuosity and channel complexity. The use of a 1D model can provide good estimates with an optimal geometry layout. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-01-14T21:30:47.115968-05:
      DOI: 10.1002/rra.2734
    • Authors: T. Asaeda; M. H. Rashid
      Pages: n/a - n/a
      Abstract: In a previous study, we found that Sparganium erectum, an emergent macrophyte, accumulates sediment inside the stand because of its phenological features. Because this species usually grows in a nutrient‐rich environment, we hypothesize that a high trophic level is maintained in the accumulated sediment. To test this hypothesis, we intensively studied flow velocity, nutrient budget and nutrient flux in and outside of S. erectum stands along the Moto‐Arakawa River, Saitama, Japan and found that the growth stages of S. erectum substantially affected the flow conditions inside the stand. The growth stages of this plant also controlled the depositional rate of sediment and organic particles. After the collapse of each cohort, a substantial amount of organic matter accumulated on the stand bed. Because the accumulated organic matter mineralized very fast, the concentration of total carbon (TC), total nitrogen (TN) and total phosphorus (TP) increased substantially after the collapse of the shoots. While the concentrations of TC, TN and TP within the stand's sediment varied seasonally, the concentrations of these elements were always higher inside than outside of the stand. More than five times the amount of carbon and twice the amount of nitrogen and phosphorus were physically retained in the stand for 1 year compared with the amounts assimilated by the plants. The ratio of carbon to nitrogen in the stand's sediment also remained constant throughout the growing period. Conversely, the nitrogen to phosphorus ratio of the accumulated sediment was much lower than that of other plant tissues. The main flow contains suspended organic solids that constantly supply the stand and partially occupy the channel where they eventually settle. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-01-14T21:01:41.921721-05:
      DOI: 10.1002/rra.2733
    • Authors: J. Pander; M. Mueller, J. Geist
      Pages: n/a - n/a
      Abstract: Stream substratum plays a key role for many riverine species and has become a focus topic in the context of structural habitat improvements. There is a lack of studies that compare the effectiveness of different substratum restoration measures. Herein, we compare four restoration techniques (two different gravel introductions, substratum raking and sickle‐formed constrictor) that were carried out in six replicate rivers. Each measure was monitored for changes in physicochemical substratum quality and the effects of the construction work on downstream sites. Generally, the effects on physicochemical substratum quality were highly variable between restoration types and rivers and strongly decreased within 1 year. Most pronounced changes of substratum quality were detected for the gravel introductions. Substratum raking and the sickle‐formed constrictor had the smallest effects, which were dependent on the original substratum composition of the restored sites. At the same time, substratum raking caused an average fine sediment deposition of 17 kg m−2 on downstream sites, being sixfold higher than for the other measures. Consequently, all of the investigated substratum restoration techniques are confined to short‐term improvement of substratum quality. This finding, together with the observed damage on downstream sites, suggests that a rethinking of the currently applied restoration techniques is required, better considering catchment and natural substratum dynamics in river restoration. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-01-13T20:51:53.703702-05:
      DOI: 10.1002/rra.2732
    • Authors: Rubén Ladrera; Maria Rieradevall, Narcís Prat
      Pages: n/a - n/a
      Abstract: The objective of this paper is to determine the alteration of the taxonomic composition and functional structure of macroinvertebrate community associated with a massive growth of the invasive algae Didymosphenia geminata downstream of a mountain reservoir (Pajares Reservoir, La Rioja, Northern Spain). As the massive growth of the alga disappears a few kilometres downstream of the reservoir associated with the input of nutrients from a nearby village sewage, we may compare the community composition between nine stations in three different conditions: three stations heavily affected by the presence of D. geminata, three further downstream stations without the algal massive growth but affected by river regulation and three control stations (unregulated and without the algae). Results show a significant disturbance of the composition and structure of macroinvertebrate community in sites affected by the stream flow regulation downstream of the dam compared with unregulated streams, but the alterations are more dramatic in the area where the growth of D. geminata is massive because of the total substrate occupation by the algal filaments. Scrapers and others invertebrates living on the coarse substrate are especially affected at such sites. Moreover, an important increase in the relative abundance of chironomids is associated with the algal massive growth, especially in case of Eukiefferiella devonica and Cricotopus spp., reducing the assemblage diversity and leading to the taxonomic and functional homogenization of the community. Changes in the reservoir management (such as releasing the water from surface rather than from the hypolimnion) may be useful to control the massive growth of D. geminata and thus reducing the effects of river regulation on macroinvertebrate assemblage composition. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-01-08T21:12:25.009347-05:
      DOI: 10.1002/rra.2731
    • Authors: C. Finch; W. E. Pine, K. E. Limburg
      Pages: n/a - n/a
      Abstract: Riverine ecosystems have been altered in many large catchments by dam development to provide water, power, flood control and navigational benefits to humans. Conservation actions in these river ecosystems are commonly focused on minimum releases of water to downstream ecosystems. Increasingly minimum release approaches are being replaced with ‘experimental’ flows that mimic natural conditions in order to benefit riverine ecosystems. While these new policies are intuitive in their design, there is limited data of how riverine ecosystems actually respond to more natural flows. A test of more natural steady‐flow water release was compared with typical fluctuating hydropower flows in the adaptive management programme at Glen Canyon Dam, Arizona, during 2008–2011 to assess growth improvements of endangered juvenile humpback chub Gila cypha. Our results are counterintuitive and show that more natural steady flows reduced growth rates of juvenile humpback chub compared with fluctuating flows when both treatments occurred within the same year. Daily growth rates during steady flows of 2009 and 2010 were 0.05 and 0.07 mm day−1 slower, respectively, than fluctuating flows those same years, despite similar water temperatures. Juvenile humpback chub also grew more slowly during steady flows that occurred in the same season. During the summer, juvenile humpback chub grew 0.12 and 0.16 mm day−1 in fluctuating flow regimes in 2009 and 2010, respectively, and only 0.07 mm day−1 in the experimental steady flow regime in 2011, despite higher water temperatures. Our results suggest that optimal conservation management policies for endangered species in regulated rivers may not always be achieved with more natural flows. Copyright © 2014 John Wiley & Sons, Ltd.
      PubDate: 2014-01-07T22:38:24.145851-05:
      DOI: 10.1002/rra.2725
    • Authors: X. S. Ai; S. Sandoval‐Solis, H. E. Dahlke, B. A. Lane
      Pages: n/a - n/a
      Abstract: Today's water systems require integrated water resource management to improve the water supply for conflicting water uses. This research explores alternative policies to improve the water supply for two conflicting uses, hydropower and environmental, using the Leishui River basin and Dongjiang reservoir as a case study. First, the natural flow regime prior to reservoir construction (pre‐1992) was estimated by performing a statistical analysis of 41 years of daily streamflow data (March 1952–February 1993). This natural flow regime was used as a template for proposing environmental flow (e‐flow) requirements. The post‐reservoir flow regime (post‐1992) (March 1993–February 2011) was analysed to estimate the streamflow alteration. Results show that the natural flow regime has been completely transformed; post‐1992 winter normal flows are greater, and summer flows are smaller than pre‐1992 conditions. Also, the occurrence of natural floods has been prevented. Second, a planning model was built of the current operation of the Dongjiang reservoir and used for comparison of four alternative water management policies that considered e‐flow releases from the Dongjiang reservoir. The scenarios that considered combinations of the current operational policy and e‐flow releases performed better in terms of hydropower generation than the current operation. Different volumes of e‐flow requirements were tested, and an annual e‐flow volume of 75% of the pre‐1992 hydrograph was determined to generate the most hydropower while providing for environmental water needs. Trade‐offs are essential to balance these two water management objectives, and compromises have to be made for both water uses to obtain benefits. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-12-26T21:22:18.296991-05:
      DOI: 10.1002/rra.2728
    • Authors: C. L. Nicol; D. P. Smith, F. G. R. Watson
      Pages: n/a - n/a
      Abstract: Yellowbank Creek is a small stream in coastal central California being assessed for salmonid habitat limiting factors and restoration potential. Yellowbank flows through low‐density marine mudstone bedrock, which is the gravel source for the stream. To assess the potential effects of the low‐density substrate on spawning gravels, a tracer stone study comparing the incipient motion of low‐density mudstone particles and typical density granitic particles was used to populate a logistic regression particle entrainment model. A model comparison approach was used to test the strength of the model. Results demonstrate partial mobility of both mudstone and granitic particles under boundary shear conditions ranging from 6.9 to 42.2 N m‐2. The modelling results quantify the strong negative correlation between particle entrainment and particle density. Mudstone gravel was three times more likely to be entrained than granitic gravel, within the context of the experimental conditions. The effect of density difference on partial mobility was greater in smaller grain size fractions. This work has implications for salmonid spawning success in atypical geologic settings and may assist in prioritization of restoration efforts. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-12-26T20:24:29.300963-05:
      DOI: 10.1002/rra.2726
    • Authors: C. J. Gardner; D. C. Deeming, P. E. Eady
      Pages: n/a - n/a
      Abstract: The increased threat of flooding from climate change requires ever greater management of rivers to alleviate flood risk. Although the impacts of river modification on fish communities are well documented, the effects of river management practices on fish behaviour have received relatively little attention. Here, a long‐term (4 years) acoustic telemetry study was used to analyse the spatial–temporal behaviour of common bream in a lowland river system (River Witham, Lincolnshire, UK) in which water levels are artificially manipulated biannually as part of a flood storage strategy. Levels are lowered in the autumn and increased again in the spring, to increase in‐river winter flood storage capacity. Home‐range size varied according to season, with home ranges being larger in the spring and summer months in comparison with those recorded during the autumn and winter months. When water levels within the river system were artificially manipulated, the bream responded by altering their home‐range size, increasing it after the levels had been raised and reducing it following the lowering of the river levels. This is in contrast to the cumulative overall distances bream were recorded to travel, which were unaffected by water level manipulation, suggesting water level manipulation did not affect activity levels. Although such changes in behaviour do not necessarily equate to a negative impact on fitness, reduced home‐range size brought about by water level manipulation does have implications for habitat availability and the number of competitive, predatory and parasitic interactions encountered. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-12-17T02:25:18.71677-05:0
      DOI: 10.1002/rra.2727
    • Authors: A. E. Draut; A. C. Ritchie
      Pages: n/a - n/a
      Abstract: Removal of two dams 32 m and 64 m high on the Elwha River, Washington, USA, provided the first opportunity to examine river response to a dam removal and controlled sediment influx on such a large scale. Although many recent river‐restoration efforts have included dam removal, large dam removals have been rare enough that their physical and ecological effects remain poorly understood. New sedimentary deposits that formed during this multi‐stage dam removal result from a unique, artificially created imbalance between fluvial sediment supply and transport capacity. River flows during dam removal were essentially natural and included no large floods in the first two years, while draining of the two reservoirs greatly increased the sediment supply available for fluvial transport. The resulting sedimentary deposits exhibited substantial spatial heterogeneity in thickness, stratal‐formation patterns, grain size and organic content. Initial mud deposition in the first year of dam removal filled pore spaces in the pre‐dam‐removal cobble bed, potentially causing ecological disturbance but not aggrading the bed substantially at first. During the second winter of dam removal, thicker and in some cases coarser deposits replaced the early mud deposits. By 18 months into dam removal, channel‐margin and floodplain deposits were commonly >0.5 m thick and, contrary to pre‐dam‐removal predictions that silt and clay would bypass the river system, included average mud content around 20%. Large wood and lenses of smaller organic particles were common in the new deposits, presumably contributing additional carbon and nutrients to the ecosystem downstream of the dam sites. Understanding initial sedimentary response to the Elwha River dam removals will inform subsequent analyses of longer‐term sedimentary, geomorphic and ecosystem changes in this fluvial and coastal system, and will provide important lessons for other river‐restoration efforts where large dam removal is planned or proposed. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.
      PubDate: 2013-12-12T21:05:00.874519-05:
      DOI: 10.1002/rra.2724
    • Authors: D. B. Hayes; B. J. Bellgraph, B. M. Roth, D. D. Dauble, R. P. Mueller
      Pages: n/a - n/a
      Abstract: Spawning habits of fall Chinook salmon in the Hanford Reach of the Columbia River have been documented with annual aerial surveys since 1948. We developed a series of models analysing these data, exploring the influence of environmental factors on the timing of redd construction. These models included a logistic regression and a dynamic modelling approach, with combinations of day of year (as a surrogate for environmental cues such as day length), water temperature and discharge as potential explanatory factors. Results of these analyses indicate that day of year was the strongest predictor of the timing of redd construction, but with significant modifying effects of water temperature and discharge. The dynamic modelling approach provides substantial advantages over a traditional logistic regression, including (1) the ability to treat data collected at non‐synchronous time intervals in a consistent fashion and (2) the ability to easily implement complex functions (e.g., threshold responses) relating behaviour to environmental cues. Evaluation of the series as a whole indicates that the median date of redd construction has increased over time, from approximately day 299 in 1950 to day 307 in 2010, as has the temperature on Oct 1 (16.3 °C–18.1 °C). The degree to which these changes are caused by climate change or dam operations is uncertain, however. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-11-28T22:49:54.995925-05:
      DOI: 10.1002/rra.2719
    • Authors: Y. Yabuhara; Y. Yamaura, T. Akasaka, F. Nakamura
      Pages: n/a - n/a
      Abstract: As anthropogenic impacts on riverine ecosystems expand, both aquatic and terrestrial ecosystems are influenced over large spatiotemporal scales. We predicted how riparian bird communities changed in response to long‐term changes in floodplain landscapes such as woodland expansion (i.e. rapid increases in vegetation cover on gravel bars and the progress of vegetation succession due to a decrease in the frequency and magnitude of flood disturbance). To test the hypothesis that woodland expansion after dam construction reduces the abundance of gravel bar‐nesting birds and increases the abundance of forest‐nesting birds, we estimated historical changes between past and present bird abundances using species distribution models across multiple rivers that were either unregulated or regulated by dams. We created past and present vegetation maps from remote sensing images and used habitat quantities as explanatory variables in the species distribution models. As we hypothesized, the estimated abundance of gravel bar‐nesting birds decreased and that of forest‐nesting birds increased because of woodland expansion in some regulated rivers. This suggests that anthropogenic alterations of riverine conditions (e.g. dam construction) can affect terrestrial ecosystems (e.g. riparian bird communities) through changes in floodplains (e.g. woodland expansion). In addition, our findings highlight the efficacy of combining spatial and temporal analyses when examining long‐term ecological dynamics. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-11-27T23:34:46.360351-05:
      DOI: 10.1002/rra.2721
    • Authors: S. Baranya; N. R. B. Olsen, J. Józsa
      Pages: n/a - n/a
      Abstract: A comprehensive flow analysis for a confluence of two medium‐sized (Qmean ≈ 30–50 m3/s) Hungarian rivers was carried out by means of a three‐dimensional Reynolds‐averaged Navier–Stokes modelling. The model was validated against detailed fixed and moving Acoustic Doppler Current Profiler velocity profiling. Unsteady simulations with steady‐state boundary conditions were performed on a structured grid in order to reveal the characteristic large‐scale spatial behaviour of the flow, such as strong secondary currents because of the river bends upstream of the confluence. Secondary current vectors indicating the swirling character of the flow were derived both from field measurements and model results showing good agreements for two different discharge ratios. Additionally, a novel approach was used to simulate the unsteady vortex shedding implementing a nested grid into the previously used coarse grid. Using a considerable finer horizontal (~0.5 m) and time (1 s) resolution, the numerical model reproduced the unsteady character of flow between the two rivers. A qualitative assessment of the mixing processes was also introduced through the example of the propagation of plaster plume used to neutralize a disastrous red mud spillage that occurred in 2010. The results indicate the combined influence of secondary currents and vortex shedding. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-11-22T03:22:05.641289-05:
      DOI: 10.1002/rra.2718
    • Authors: M. W. Heath; S. A. Wood, K. A. Brasell, R. G. Young, K. G. Ryan
      Pages: n/a - n/a
      Abstract: Global demand for freshwater has led to unprecedented levels of water abstraction from riverine systems. This has resulted in large alterations in natural river flows. The deleterious impacts of reduced flows on fish and macroinvertebrate abundances have been thoroughly investigated; in contrast, there is a limited understanding of the potential for changes in the abundance of nuisance benthic algal/cyanobacterial blooms. In New Zealand, Phormidium sp. blooms are common in numerous rivers during summer low flows. In this study, an in‐stream habitat assessment is used to examine the relationship between Phormidium habitat availability and reducing flows. Over 650 observations of Phormidium mats, from seven sites (Hutt River, lower North Island, New Zealand), were used to construct habitat suitability curves for depth, velocity and substrate. Preference curves were fitted using both the ‘forage ratio’ and ‘quantile regression’ methods. Phormidium growth, observed at all seven sites, increased significantly from upstream (uppermost site, 5.2% mat cover) to downstream (63.5%). The habitat suitability curves revealed Phormidium had a large tolerance to velocity, depth and substrate type. Consequently, decreases in flow had only negligible effects on available Phormidium habitat. During periods of stable flow, Phormidium abundance positively correlated with increased nitrogen concentrations, potentially explaining the large variation in Phormidium cover from upstream to downstream. Quantile regression generated habitat suitability criteria were a more accurate predictor of available Phormidium habitat than the forage ratio criteria. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-11-20T22:19:50.340574-05:
      DOI: 10.1002/rra.2722
    • Authors: K. J. Jenkins; N. D. Chelgren, K. A. Sager‐Fradkin, P. J. Happe, M. J. Adams
      Pages: n/a - n/a
      Abstract: The downstream transport of sediments and organics and upstream migration of anadromous fishes are key ecological processes in unregulated riverine ecosystems of the North Pacific coast, but their influence on wildlife habitats and populations is poorly documented. Removal of two large hydroelectric dams in Washington's Elwha Valley provides an unprecedented opportunity to study long‐term responses of wildlife populations to dam removal and restoration of these key ecological processes. We compared pre‐dam removal patterns in the relative abundance and occupancy of mesocarnivores, small mammals and lentic amphibians of the Elwha River riparian zone above, between and below the dams. Occupancy of riparian habitats by three mesocarnivore species diminished upriver but did not appear to be closely linked with the absence of salmon in the upper river. Although the importance of salmon in the lower river cannot be discounted, other gradients in food resources also likely contributed to observed distribution patterns of mesocarnivores. Abundance and occupancy patterns within congeneric pairs of new world mice (Peromyscus spp.) and shrews (Sorex spp.) indicated that closely related species were negatively associated with each other and responded to habitat gradients in the riparian zone. The availability of lentic habitats of amphibians was highly variable, and occupancy was low as a result of rapidly changing flows during the larval development period. We speculate that long‐term changes in habitat conditions and salmon availability following dam removal will elicit long‐term changes in distribution of mesocarnivores, small mammals and amphibians. Long‐term monitoring will enhance understanding of the role of fish and restored ecosystem processes on wildlife communities along salmon‐bearing rivers in the region. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-11-20T21:06:46.820303-05:
      DOI: 10.1002/rra.2723
    • Authors: M. J. Bond; N. E. Jones
      Pages: n/a - n/a
      Abstract: Deviation from a river's natural flow regime is considered to be one of the most serious and continuing threats to lotic ecosystems. Peaking hydroelectric facilities, which are designed to adjust the level of power generation in accordance with hourly energy demand, can dramatically alter flows and temperatures and ultimately lead to changes in the quantity and quality of habitat available to fish. In this study, we examine the spatial distribution of river fishes, benthic invertebrates and organic matter along lateral and longitudinal gradients in two hydropeaking and eight natural Lake Superior tributaries in Ontario, Canada. This study demonstrates that (i) hourly variation in flow, caused by hydropeaking, results in a varial zone that supports significantly fewer fish than the adjacent permanently wetted channel and (ii) strong longitudinal gradients in fish biomass, particularly for sedentary species such as slimy sculpin (Cottus cognatus), exist in regulated rivers, and fish biomass is up to four times greater at sites directly below the peaking dams than at sites further downstream or in nearby natural rivers. Gradients in the spatial distribution of fishes closely follow changes in food resources such as benthic organic matter and invertebrates, suggesting that these gradients are driven by spatial shifts in food availability and are ultimately caused by gradients in abiotic habitat variables. Monitoring and assessment efforts should take into account that lateral and longitudinal gradients exist in regulated rivers, and this understanding must be incorporated into sampling programmes. Failing to do so could alter the interpretation of river productivity, integrity and health. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-11-19T23:35:09.157872-05:
      DOI: 10.1002/rra.2720
    • Authors: B. Belletti; S. Dufour, H. Piégay
      Pages: n/a - n/a
      Abstract: Several decades of human activities have severely impacted braided rivers worldwide. Despite their widespread disappearance, some remnant braided sectors are still held in the French Rhone basin, mainly in the south‐east of France. In this paper, we analyse the evolutionary pattern of 53 braided reaches, focusing on the active channel width and island patterns, by comparing aerial photographs from the 1950s and 2000s (Institut Géographique National). Because different braided patterns exist (e.g. bar versus island‐braided), we tested the relative effect of geographical and temporal factors. The hypothesis is that three main biogeomorphological braided types exist (i.e. defined through the presence, the amount and the relative size of vegetated islands), based on the combined effect of the following: (i) their position along the river network (i.e. river gradient, altitude and sediment regime) and (ii) the temporal effect represented by the time since the last large flood, that is, the recent flood history. Our results show that even if the regional context (climate and sediment regime mainly) plays a key role, the temporal factor, represented by recent flood history, seems to heavily influence the response of the width pattern and vegetation recovery. Local factors (i.e. topography and groundwater) may also have an impact, but their influence has no effect at the regional level. These results support braided river management (conservation and/or restoration actions) in the Rhone basin and provide a better understanding of the range of braided rivers' functioning. Further studies (e.g. multidate retrospective survey) are needed to better understand the role of flood events on braided pattern and vegetation recovery. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-11-19T01:54:12.625855-05:
      DOI: 10.1002/rra.2714
    • Authors: M. J. Feio; W. R. Ferreira, D. R. Macedo, A. P. Eller, C. B. M. Alves, J. S. França, M. Callisto
      Pages: n/a - n/a
      Abstract: Here, we set target values to measure the ecological improvement of streams, based on invertebrate communities, riparian vegetation, instream habitat conditions and water chemistry. The study area is a large tropical catchment (Rio das Velhas, Minas Gerais, Brazil) affected by pastures, mining areas and a large urbanized area but also includes natural protected areas. Two stream types were found in the catchment, based on stream size, elevation, climate and geology with significantly different macroinvertebrate communities. In spite of a marked wet/dry seasons' climatic pattern, that does not result in the segregation of communities. Four classes of global degradation (IV—bad to I—good condition) were defined based on the available abiotic information, corresponding to a gradient in structure and biotic metrics of macroinvertebrate communities, matching the current knowledge on taxa sensitivity to pollution and general disturbance. Class I corresponds to target conditions to be achieved under restoration programmes. Using this approach, we were able to detect an improvement of abiotic conditions in four urban streams that benefited from enhancement measures in 2007–2008. However, invertebrate communities improved clearly in only one site (biotic metrics and community structure). Our study highlighted that good water quality alone is not enough and that only the combined effect of water quality, riparian vegetation and instream habitat condition enhancement resulted in the improvement of invertebrate communities. An important limiting factor for macroinvertebrate communities' recovery may be the distance to source populations. We concluded that the combined use of biological and abiotic target values for measuring the recovery of streams is needed to fully achieve an ecological restoration. This approach can also be valuable in the regular monitoring of streams to assess stream degradation. Target values based on other biological elements, such as fishes and algae, and functional processes could also contribute to define more global and realistic goals. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-11-08T03:45:21.806462-05:
      DOI: 10.1002/rra.2716
    • Authors: D. M. Smith; D. M. Finch
      Pages: n/a - n/a
      Abstract: Nonnative plant invasions are a management concern, particularly in riparian forests, but little is known about mechanisms through which they influence vertebrate communities. In the American Southwest, native trees such as cottonwood (Populus spp.) are thought to provide better habitat for breeding birds than nonnative plants, which are more tolerant of human‐altered conditions. To evaluate effects of riparian forest composition on riparian‐nesting birds, we examined nest plant use along two rivers in New Mexico that differed in abundance of nonnative vegetation. Of the nests we observed, 49% along the Middle Rio Grande were constructed in nonnative plants, compared with 4% along the Gila River. Birds in the canopy and cavity‐nesting guilds constructed less than 5% of their nests in nonnative plants along either river. At the Middle Rio Grande, birds in the subcanopy/shrub guild constructed 67% of their nests in nonnative plants. Despite the relatively low availability of cottonwoods, they were used by greater numbers of species than any other woody plant at either river. Riparian obligates and species of conservation concern in the canopy and cavity guilds were especially dependent on cottonwood and Arizona sycamore (Platanus wrightii). Our results show that, although nonnative trees and shrubs support large numbers of nests for certain birds, cottonwoods and other large native trees are disproportionately important to riparian bird communities. Copyright © 2013 John Wiley & Sons, Ltd.
      PubDate: 2013-11-08T03:18:51.667057-05:
      DOI: 10.1002/rra.2713
    • Authors: M. Gard
      Pages: 40 - 44
      Abstract: The River2D two‐dimensional hydraulic and habitat model was used to simulate fall‐run Chinook salmon (Oncorhynchus tschawytscha) spawning and fry and juvenile rearing habitat of the first phase of a stream channel restoration project on Clear Creek, California. Habitat was simulated for a range of stream flows: (1) before restoration; (2) based on the restoration design; (3) immediately after restoration; and (4) after one and two large flow events. Hydraulic and structural data were collected for three sites before restoration, and prerestoration habitat was simulated. Habitat simulated for these sites was extrapolated to the prerestoration area based on habitat mapping. The topographical plan for the restoration was used to simulate the anticipated habitat after restoration. Although the restoration increased spawning habitat, it was less successful for rearing habitat. Channel changes associated with high‐flow events did not entirely negate the benefits of the restoration project. The results of this study point out the need for models that can simulate the changes in channel topography associated with high‐flow events, which could then be used to simulate habitat over time. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.
      PubDate: 2013-01-24T20:21:29.705524-05:
      DOI: 10.1002/rra.2642
           Arthington. 2012. University of California Press: Berkeley, 424. (ISBN
           978‐0‐520‐27369‐6) Price: £52.00
    • Authors: Emma Neachell
      Pages: 132 - 133
      PubDate: 2013-01-08T00:17:10.052454-05:
      DOI: 10.1002/rra.2635
    • Authors: J. A. Crossman; L. R. Hildebrand
      Pages: 1 - 10
      Abstract: Site‐specific habitat alterations have improved spawning success and early life stage survival of different fish species, including sturgeon, in regulated rivers. We modified the substrate within a section of river at the only known spawning site used by white sturgeon (Acipenser transmontanus) in the Mid Columbia River, Canada. Existing armoured riverbed conditions were modified using a mixture of larger and smaller angular rock with the assumption that the larger material would remain in place at higher discharges and help retain the smaller material. This increased substrate complexity and the amount of available interstitial spaces. We stocked 2‐day posthatch larvae over both the modified site and at an adjacent control site that represented existing substrate conditions. Our objectives were to determine (i) the extent that stocked larvae remained in both the modified and control sites immediately after release, (ii) the timing of subsequent dispersal of larvae from both sites and (iii) how total length of dispersing larvae changed over time and by site. Results from this work indicated that the modified section of riverbed retained significantly higher numbers of larvae after release compared with the control site. Larvae at the modified site were able to hide and remain within the substrate and initiated downstream drift 15 days after release. With the exception of the first day after release, dispersal from both sites occurred at night. There was a significant effect of time after release and site on the total length of dispersing larvae. The larger variation in total larval length observed at the control site compared with the modified site indicated greater difficulty in hiding within the control substrate. Larvae initiated dispersal from the modified site at a mean size of 17.5 mm, which may indicate an important growth threshold before drift. Results from this work are important for future mitigative efforts for sturgeon in regulated rivers where changes to spawning substrates have occurred. Copyright © 2012 John Wiley & Sons, Ltd.
      PubDate: 2012-11-07T03:12:02.675576-05:
      DOI: 10.1002/rra.2620
    • Authors: B. G. Justus; S. V. Mize, J. Wallace, D. Kroes
      Pages: 11 - 28
      Abstract: Dissolved oxygen (DO) concentrations in lowland streams are naturally lower than those in upland streams; however, in some regions where monitoring data are lacking, DO criteria originally established for upland streams have been applied to lowland streams. This study investigated the DO concentrations at which fish and invertebrate assemblages at 35 sites located on lowland streams in southwestern Louisiana began to demonstrate biological thresholds. Average threshold values for taxa richness, diversity and abundance metrics were 2.6 and 2.3 mg/L for the invertebrate and fish assemblages, respectively. These thresholds are approximately twice the DO concentration that some native fish species are capable of tolerating and are comparable with DO criteria that have been recently applied to some coastal streams in Louisiana and Texas. DO minima >2.5 mg/L were favoured for all but extremely tolerant taxa. Extremely tolerant taxa had respiratory adaptations that gave them a competitive advantage, and their success when DO minima were
      PubDate: 2012-11-12T23:08:04.310873-05:
      DOI: 10.1002/rra.2623
    • Authors: D. M. Carlisle; S. M. Nelson, K. Eng
      Pages: 29 - 39
      Abstract: Natural streamflows play a critical role in stream ecosystems, yet quantitative relations between streamflow alteration and stream health have been elusive. One reason for this difficulty is that neither streamflow alteration nor ecological responses are measured relative to their natural expectations. We assessed macroinvertebrate community condition in 25 mountain streams representing a large gradient of streamflow alteration, which we quantified as the departure of observed flows from natural expectations. Observed flows were obtained from US Geological Survey streamgaging stations and discharge records from dams and diversion structures. During low‐flow conditions in September, samples of macroinvertebrate communities were collected at each site, in addition to measures of physical habitat, water chemistry and organic matter. In general, streamflows were artificially high during summer and artificially low throughout the rest of the year. Biological condition, as measured by richness of sensitive taxa (Ephemeroptera, Plecoptera and Trichoptera) and taxonomic completeness (O/E), was strongly and negatively related to the severity of depleted flows in winter. Analyses of macroinvertebrate traits suggest that taxa losses may have been caused by thermal modification associated with streamflow alteration. Our study yielded quantitative relations between the severity of streamflow alteration and the degree of biological impairment and suggests that water management that reduces streamflows during winter months is likely to have negative effects on downstream benthic communities in Utah mountain streams. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.
      PubDate: 2012-11-21T10:39:40.116025-05:
      DOI: 10.1002/rra.2626
    • Authors: D. Corenblit; J. Steiger, E. Tabacchi, E. González, A‐M Planty‐Tabacchi
      Pages: 45 - 59
      Abstract: Patterns of native and exotic plant species richness and cover were examined in relation with ecosystem engineer effects of pioneer vegetation within the Mediterranean gravel bed river Tech, South France. The floristic composition was characterized according to two distinct vegetation types corresponding to two habitats with contrasted conditions: (i) open and exposed alluvial bars dominated by herbaceous communities; and (ii) islands and river margins disconnected from annual hydrogeomorphic disturbances and covered by woody vegetation. A significant positive correlation between exotic and native plant species richness and cover was observed for both vegetation types. However, significant differences in native and exotic species richness and cover were found between these two vegetation types. Higher values of total species richness and Shannon diversity were attained within the herbaceous vegetation type than within the woody type. These differences are most likely related to changes in local exposure to hydrogeomorphic disturbances driven by woody engineer plant species and to vegetation succession. A lower exotic species cover within the woody vegetation type than within the herbaceous type suggested an increase of resistance to invasion by exotic species during the biogeomorphic succession. The engineer effects of woody vegetation through landform construction resulted in a decrease of alpha (α) diversity at the patch scale but, in parallel, caused an increase in gamma (γ) diversity at the scale of the studied river segment. Our study corroborates recent investigations that support the theory of biotic acceptance of exotic species by native species at the local scale (generally
      PubDate: 2012-10-30T01:05:30.803675-05:
      DOI: 10.1002/rra.2618
    • Authors: L. V. Reynolds; D. J. Cooper, N. T. Hobbs
      Pages: 60 - 70
      Abstract: Understanding mechanisms of exotic species' invasions is essential to managing riparian landscapes throughout the world. In the southwestern USA, the two most dominant invaders of riparian habitats are the exotic tree species tamarisk (Tamarix ramosissima, Tamarix chinensis, and their hybrids) and Russian olive (Elaeagnus angustifolia). These plants were introduced around 1900, and their success may be facilitated by river regulation, river channel changes, and precipitation patterns. We hypothesized that riparian invasion in Canyon de Chelly, Arizona, was initiated by a change point event such as plantings, dam construction, or channel incision and that establishment near a change point was tied to flood events. We aged tamarisk, Russian olive, and native cottonwood trees from study sites in Canyon de Chelly and used tree ring analysis to determine the year of establishment and the elevation of the germination point relative to the channel. We used Bayesian Poisson regression and information theoretics to identify change points and precipitation variables driving annual tree establishment. We found that most tamarisk and Russian olive trees established in the late 1980s, and most cottonwoods established in 1930‐1950 and 1980‐2000. Regression models indicated that change points occurred in 1983 for Russian olive and 1988 for tamarisk, and precipitation was important for establishment. Although plantings and river regulation probably played a role in tree invasion, our results suggest that these species required precipitation and stream channel change for widespread establishment in Canyon de Chelly. The factors driving riparian invasions may not be those often associated with degraded rivers, such as altered hydrographs and land management changes, thus requiring analyses of the full range of ecological and physical processes. Copyright © 2012 John Wiley & Sons, Ltd.
      PubDate: 2012-10-30T01:15:26.565288-05:
      DOI: 10.1002/rra.2619
    • Authors: L. Davis; C. P. Harden
      Pages: 71 - 80
      Abstract: Bank failure is a common fluvial process and can be a pervasive fluvial response to natural and anthropogenic disturbances. Previous research has identified causes and types of bank failure, but the conditions that lead to the cessation of bank failure remain poorly explained. This research examines differences between banks with active bank failure and banks that exhibit evidence of past bank failure that ceased (dormant) throughout three West Tennessee (USA) rivers to provide insight into the processes that cause bank failure to end. Bank characteristics were observed at 68 sites, and data from 55 banks were used to create a logistic regression model. Bank characteristics entered into the model included: vegetative cover, failure location, bar association, bank material, channel width‐to‐depth (w/d) ratio, and average bank angle. Results of the logistic regression suggest that bank angle best explains (p = 0.31 and odds ratio = 8.2) the difference between banks with active and dormant bank failure. Interestingly, vegetative cover and bank material composition, which have been found to be important in bank stabilization by previous researchers, were not significant predictors of bank stability according to the logistic regression model. These results suggest that in absence of drastic differences in bank material resistance (bedrock vs sediment): (1) spatial patterns of bank failure at the system‐scale will be diffuse, (2) bank stability can require a multiple decades, and (3) the potential for vegetation to stabilize banks may be limited in some alluvial systems because of positive feedbacks created by repeated human disturbance. Copyright © 2012 John Wiley & Sons, Ltd.
      PubDate: 2012-11-26T19:46:00.334825-05:
      DOI: 10.1002/rra.2621
    • Authors: V. Ruiz‐Villanueva; A. Díez‐Herrero, J. A. Ballesteros, J. M. Bodoque
      Pages: 81 - 97
      Abstract: In‐depth knowledge of the fluvial corridor and surrounding slopes and forest vegetation is needed for a better understanding of wood recruitment or inputs to rivers. The information available in Central Spain on hydrogeomorphic processes and forest distribution enabled the evaluation of potential wood recruitment from three sources: landslides, bank erosion and fluvial transport during floods on a regional scale. The method presented here is based on a geographical information system (GIS) and on multi‐criteria and multi‐objective assessment using fuzzy logic principles. First, the areas potentially affected by landslides, bank erosion and floods were delineated, and a vegetation analysis was carried out to obtain the vegetation resistance and forest density. Several scenarios were proposed based on the process frequency and severity. Using this method, the volume of potentially available wood can be estimated for each scenario. Fourteen river basins in populated areas were selected for further analyses and field survey. Observations of in‐stream storage of woody debris and tree disturbances were used to interpret the woody debris dynamics throughout the watershed and validate the obtained results. This method offers a suitable approach to define a watershed's capacity to recruit wood material to streams by delineating the source areas and estimating the order of magnitude of the wood volume in each case. The results may be useful to characterize the dynamics of woody debris from the perspective of the potential hazard of its transport during floods, and they can also be used for forest and river management and restoration. Copyright © 2012 John Wiley & Sons, Ltd.
      PubDate: 2012-10-17T01:48:21.511431-05:
      DOI: 10.1002/rra.2614
           WOOD IN RIVERS
    • Authors: A. Chin; L. R. Laurencio, M. D. Daniels, E. Wohl, M. A. Urban, K. L. Boyer, A. Butt, H. Piegay, K. J. Gregory
      Pages: 98 - 111
      Abstract: This article reports a survey of 196 river managers in seven states across the USA assessing their perceptions of in‐stream wood. This survey followed corresponding questionnaires given to undergraduate students representing non‐expert views in the same states and in 10 countries around the world. Whereas most students registered predominantly negative views of in‐stream wood (i.e. not aesthetically pleasing, dangerous and needing improvement), American managers perceive rivers with wood as significantly more aesthetically pleasing, less dangerous and needing less improvement than rivers without wood. These views were consistent across different types of managers (conservation, fisheries, forestry, recreation and water), suggesting that because of education, training and field experience beyond the undergraduate degree, managers gain more positive views of in‐stream wood. Analysis of manager responses grouped by years in the profession suggests that professional experience or information within professional networks plays a role. As years worked in the profession increase, managers' responses to photos with and without wood became significantly different, showing sharper discernment in viewing in‐stream wood more positively. We conceptualize evolving management strategies involving wood in American rivers as a series of iterative states within changing human–landscape systems produced by interacting impacts and feedbacks. In this example application, the Interactive, Integrative, and Iterative (III) Framework for Human Landscape Change highlights the importance of public education and policy as necessary feedback linkages to close the gap between people's perceptions of wood and scientific advances that recognize the significant role of wood in rivers. Copyright © 2012 John Wiley & Sons, Ltd.
      PubDate: 2012-10-24T00:06:03.683743-05:
      DOI: 10.1002/rra.2617
    • Authors: E. Wohl; N. Beckman
      Pages: 112 - 131
      Abstract: Channel‐spanning logjams completely span the active channel and create longitudinal discontinuities of the water surface and stream bed across at least two‐thirds of the channel width. These jams disproportionately affect channel process and form relative to smaller jams that do not span the entire channel width. We analyze a spatially extensive dataset of 859 channel‐spanning jams distributed along 124 km of 16 distinct rivers on the eastern side of Rocky Mountain National Park, Colorado, USA, with drainage areas spanning 2.6 to 258 km2 and diverse valley geometry and forest stand age. We categorized valley geometry in terms of lateral confinement (confined, partly confined, or unconfined), which correlates with gradient. Jams exhibit substantial downstream variability in spacing at channel lengths of 102–103 m. The number of jams within a reach is explained by a statistical model that includes drainage area, valley type (lateral confinement), and channel width. Longitudinal spacing of jams drops substantially at drainage areas greater than ~20 km2, although jam spacing exhibits tremendous variability at smaller drainage areas. We interpret the lack of jams at larger drainage areas to reflect increasing transport capacity for instream wood. We interpret the variability in jam spacing at small drainage areas to reflect local controls of valley geometry and associated wood recruitment and fluvial transport capacity. Our results suggest that management of instream wood designed to facilitate the formation of channel‐spanning jams can be most effectively focused on smaller drainage areas where these jams are most abundant in the absence of management that alters instream wood recruitment or retention. Unmanaged streams in the study region with drainage area
      PubDate: 2012-11-21T10:23:24.155608-05:
      DOI: 10.1002/rra.2624
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