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Arturo Elosegi - One of the best experts on this subject based on the ideXlab platform.
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Nutrient uptake in a Stream affected by hydropower plants: comparison between Stream Channels and diversion canals
Hydrobiologia, 2013Co-Authors: Oihana Izagirre, Alba Argerich, Eugènia Martí, Arturo ElosegiAbstract:Small hydropower plants divert part of the water from wide and physically complex Stream Channels with active hyporheic areas to narrow and hydraulically simple concrete canals, and thus, might affect nutrient dynamics. We compared nutrient uptake in diversion canals and in Stream Channels in the Leitzaran Stream (Basque Country, northern Spain). We predicted that simple morphology in diversion canals will result in lower nutrient uptake in canals than in Stream Channels. Periphytic chlorophyll and biomass did not differ significantly between reach types. Water was significantly deeper and faster in canals than in Stream Channels, but the transient storage zone did not differ significantly between reach types. There were no significant differences between uptake length for neither phosphate nor ammonium between reach types. Uptake length in both Stream Channels and diversion canals decreased with discharge, in a pattern similar to that previously described for pristine rivers across the world. Uptake velocity and uptake rate for phosphate did not differ significantly between reach types, but in the case of ammonium both retention metrics were significantly larger in the diversion canals. Results suggest that although hydropower schemes have minor effects on nutrient retention, these depend on the proportion of flow diverted.
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restoration of dead wood in basque Stream Channels effects on brown trout population
Ecology of Freshwater Fish, 2011Co-Authors: Alvaro Anton, Arturo Elosegi, Loreto Garciaarberas, Joserra Diez, Ana RalloAbstract:– Streams in the Aiako Harria Natural Park (Basque Country, Spain) have excellent water quality, but are physically impoverished after centuries of snagging. In an attempt to restore channel complexity and ecosystem functioning, especially in-channel retention of sediments and organic matter, large woody debris (LWD) was introduced into four mountain Streams (channel width 3–13 m) following a before/after, control/impact (BACI) design. Logs were introduced by means of hand-held machinery and located uncabled, mimicking the natural amount and disposition of LWD in Streams. Floods disrupted most of the structures at the large Stream, but caused little damage to those in the small ones. Only minnow and brown trout inhabit in the area. Before wood addition, trout densities were fairly high in the small Streams, low in the large one, where recruitment seemed very poor. In the small tributaries, trout populations showed a strong imbalance towards young fish, adults being only found in the spawning season. Wood addition produced some interesting trends in trout, although statistical significance was low as a result of large environmental variability. Fish densities showed small changes, but biomass increased, especially in the spawning season. Also, there was a trend towards more aged 2+ or larger, thus suggesting wood addition improved adult habitat. Although restoring LWD is extremely unusual in Spain, the changes in physical habitat and the trends in fish populations detected in the present project suggest it is worth making more experiments, at least in safe settings where there is no risk of flooding or damaging properties.
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leaf retention in Streams of the aguera basin northern spain
Aquatic Sciences, 2003Co-Authors: Santiago Larranaga, Arturo Elosegi, Jose Ramon Diez, Jesus PozoAbstract:The capacity of Stream Channels to retain leaf litter (retentiveness) was measured in 21 reaches of the Aguera basin (northern Spain) at different discharges, using plastic strips as leaf analogs. Strips were calibrated against seven local leaf species occurring in the area. Retention was highest for alder, followed by plastic strips, oak, beech, chestnut, eucalyptus, hazel, and sycamore. Inter-specific differences in retention were great, and not clearly related to leaf form or size. This result shows that a great deal of caution is necessary to compare results obtained by authors using different leaf species. The Aguera Stream Channels were highly retentive, especially in the headwaters. At baseflows, the average travel distance of strips was 3.6 m in 1st-order reaches, increasing to 16.6 m in 3rd-order Streams. Travel distances of strips increased twofold in 3rd- and 2nd-order reaches and 5-fold in 1st-order Streams during periods of high discharge. Leaf litter retentiveness was related to channel gradient, width, and substrate. Cobbles and wood showed high retention efficiencies, and the role of wood as a retention factor increased at high discharges. Retentiveness enhances storage and subsequent utilization of organic materials in forested Streams, and thus should be taken into account when managing Streams.
William L Graf - One of the best experts on this subject based on the ideXlab platform.
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james c knox 1977 human impacts on wisconsin Stream Channels annals of the association of american geographers 67 224 244
Progress in Physical Geography, 2013Co-Authors: William L GrafAbstract:James C. Knox’s 1977 paper “Human Impacts on Wisconsin Stream Channels,” published in the Annals of the Association of American Geographers, was a key component of a suite of three papers by him defining the response of rivers to the introduction and management of agriculture and to climate change. In this paper he used the Driftless Area of southwest Wisconsin as a laboratory where he could define fluvial responses by their sedimentary signatures in floodplain deposits. Land-use records dating back to the early 19th century along with shorter climate records provided his understanding of the drivers of change. He found that floods increased as an outcome of land-cover change. UpStream tributaries became wider and shallower as coarse deposits limited their adjustments, while main stem Channels became narrower and deeper. His paper reflected the influence of his graduate advisor and especially of prominent faculty colleagues at the University of Wisconsin from fields ranging from soils and climatology to g...
G M Kondolf - One of the best experts on this subject based on the ideXlab platform.
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large woody debris in urban Stream Channels redefining the problem
River Research and Applications, 2012Co-Authors: N S Lassettre, G M KondolfAbstract:Large woody debris (LWD) is an important ecological element in rivers and Streams. Despite its importance, LWD is often removed from urban Stream Channels for flood control or road maintenance purposes, an approach with high economic and ecological costs and one that is largely unsuccessful. We propose an approach to conserve LWD in Channels by modifying infrastructure (culverts and bridges) to allow LWD passage, maintaining aquatic habitat and reducing flooding and road maintenance costs. In Soquel Creek (California, USA), which has a history of LWD-related flooding, we compared long-term LWD management costs of historical, current and a LWD-passing approach whereby infrastructure is enlarged to accommodate LWD passage downStream. We estimated costs of infrastructure replacement, programmatic flood control (LWD removal), LWD-related flood damage and lost aquatic habitat. The amount of lost aquatic habitat was determined by comparing LWD loading (pieces m−1) in Soquel Creek (0.007 pieces m−1) to nearby unmanaged Streams (0.054 to 0.106 pieces m−1). Estimated costs of infrastructure able to pass LWD were nearly double that of historical costs but comparable to current costs. The LWD-passing approach was comparable to removal approaches in the short term (1 to 50 years) but much less in the long term (51 to 100 years), as expenditures in infrastructure replacement to accommodate LWD yielded reductions in flooding costs and habitat loss. Given the urgency to maintain and restore aquatic habitat, the proposed approach may be broadly applicable. Copyright © 2011 John Wiley & Sons, Ltd.
Emily Zefferman - One of the best experts on this subject based on the ideXlab platform.
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experimental tests of priority effects and light availability on relative performance of myriophyllum spicatum and elodea nuttallii propagules in artificial Stream Channels
PLOS ONE, 2015Co-Authors: Emily ZeffermanAbstract:Submersed macrophytes have important ecological functions in many Streams, but fostering growth of beneficial native species while suppressing weedy invasives may be challenging. Two approaches commonly used in management of terrestrial plant communities may be useful in this context: (1) altering resource availability and (2) establishing desirable species before weeds can invade (priority effects). However, these approaches are rarely used in aquatic systems, despite widespread need for sustainable solutions to aquatic weed problems. In artificial Stream Channels in California, USA, I conducted experiments with asexual propagules of non-native invasive Myriophyllum spicatum (Eurasian watermilfoil) and native Elodea nuttallii (western waterweed) to address the questions: (1) How does light availability affect relative performance of the two species?; (2) Does planting the native earlier than the invasive decrease survival or growth rate of the invasive?; and (3) Do light level and priority effects interact? The relative performance between E. nuttallii and M. spicatum had an interesting and unexpected pattern: M. spicatum had higher growth rates than E. nuttallii in the zero and medium shade levels, but had similar performance in the low and high shade levels. This pattern is most likely the result of E. nutallii’s sensitivity to both very low and very high light, and M. spicatum’s sensitivity to very low light only. Native priority did not significantly affect growth rate or survival of M. spicatum, possibly because of unexpectedly poor growth of the E. nuttallii planted early. This study suggests that altering light levels could be effective in reducing growth of an invasive macrophyte, and for changing the competitive balance between a native and a non-native species in the establishment phase. Further investigations into the use of priority effects and resource alteration for submersed macrophyte management are warranted, given their mixed results in other (limited) studies.
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increasing canopy shading reduces growth but not establishment of elodea nuttallii and myriophyllum spicatum in Stream Channels
Hydrobiologia, 2014Co-Authors: Emily ZeffermanAbstract:Submersed macrophytes are often important drivers of inStream structure and function, but can be problematic when overabundant. The establishment success, growth rates, and morphology of submersed macrophytes could be affected by alteration of inStream light levels during riparian restoration (via removing or planting canopy-forming vegetation), potentially influencing the success of riparian restoration projects aimed at improving aquatic habitats. To examine the effects of canopy shading on two common submersed macrophytes—Elodea nuttallii (native) and Myriophyllum spicatum (non-native)—I conducted experiments in artificial Stream Channels in two locations in California, USA. Initial establishment of stem fragments of both species was close to 100% in all shade levels, including shade that reduced incident light by 94%. Growth rates of the two species were similar across shade levels, and lowest in the highest shade. Full light appeared to have a photoinhibitory effect on E. nuttallii at the higher elevation site. Higher shade increased the length:biomass ratio and decreased the branching of E. nuttallii. My findings suggest that altering canopy cover during riparian restoration is unlikely to affect the ability of these species to establish, but higher shade levels should slow their growth and create more favorable conditions for other inStream organisms.
W. K. Annable - One of the best experts on this subject based on the ideXlab platform.
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quasi equilibrium conditions of urban gravel bed Stream Channels in southern ontario canada
River Research and Applications, 2012Co-Authors: W. K. Annable, C. C. Watson, P. J. ThompsonAbstract:Urban gravel-bed Stream Channels in southern Ontario, Canada identified to be in a state of quasi-equilibrium have been studied over the past 15 years and compared against rural gravel bed Stream Channels of the same hydrophysiographic region. Bankfull width and depth versus bankfull discharge were not found to increase as a function of increasing urbanization as has been found in many other studies. The observed annual frequency of bankfull discharge was typically less than a 1-year return period with many sites ranging between 2 and 18 bankfull events per year with higher intensity and shorter duration urban flood responses, which further identified significant limitations in using annual peak discharge methods for predicting morphological forming flows in urban watersheds. The cumulative volume of bankfull and larger flood events from the urban Stream Channels were very similar to the same annual event volumes in the rural comparison study reaches. Bed material supply was found to decrease with increasing urbanization and the reduction in bed material supply appears to be off-set by the smaller bankfull channel width, depth and access to floodplains during large flood events. Field evidence may also suggest a even greater reduction in channel width trajectory, relative to the rural setting, with expansive floodplains to maintain quasi-equilibrium conditions as bed material supply continues to decrease with increased anthropogenic activity. Copyright © 2010 John Wiley & Sons, Ltd.
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Quasi‐equilibrium conditions of urban gravel‐bed Stream Channels in southern Ontario, Canada
River Research and Applications, 2010Co-Authors: W. K. Annable, C. C. Watson, P. J. ThompsonAbstract:Urban gravel-bed Stream Channels in southern Ontario, Canada identified to be in a state of quasi-equilibrium have been studied over the past 15 years and compared against rural gravel bed Stream Channels of the same hydrophysiographic region. Bankfull width and depth versus bankfull discharge were not found to increase as a function of increasing urbanization as has been found in many other studies. The observed annual frequency of bankfull discharge was typically less than a 1-year return period with many sites ranging between 2 and 18 bankfull events per year with higher intensity and shorter duration urban flood responses, which further identified significant limitations in using annual peak discharge methods for predicting morphological forming flows in urban watersheds. The cumulative volume of bankfull and larger flood events from the urban Stream Channels were very similar to the same annual event volumes in the rural comparison study reaches. Bed material supply was found to decrease with increasing urbanization and the reduction in bed material supply appears to be off-set by the smaller bankfull channel width, depth and access to floodplains during large flood events. Field evidence may also suggest a even greater reduction in channel width trajectory, relative to the rural setting, with expansive floodplains to maintain quasi-equilibrium conditions as bed material supply continues to decrease with increased anthropogenic activity. Copyright © 2010 John Wiley & Sons, Ltd.
