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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.

Segmenting the continuum of rivers into homogeneous reaches is an important issue in river research and management. Automatic procedures provide significance, objectivity, and repeatability. Although univariate techniques are frequently used to identify river reaches, multivariate approaches offer a more integrative context. Three nonparametric methods (multi-response permutation procedures (MRPP) with an advance in the significance level estimation, the Pettitt and Mann–Kendall tests) are applied for segmenting the river based on three geomorphic variables (valley width, active channel width, and channel slope) systematically measured in a GIS environment. The cited techniques have been applied to the Curueno River (NW Spain) to illustrate the methods, we analyse reach distribution along the river longitudinal profile. The methods successfully characterize the evident transitions along fluvial systems and also others less noticeable. The three methods provide more reaches according to valley width and less reaches according to channel slope (18.0 and 3.7 reaches on average, respectively). In contrast to the Mann–Kendall test, MRPP and Pettitt tests provide more stable segmentations when significance level varies. However, the Pettitt test provides irregular segmentations for regular patterns. The MRPP both univariate and multivariate applications enables a wider scope for the segmentation issue, which is useful in diverse aspects of fluvial domain.

A set of multi-scale, process-based hydromorphological indicators of river character and dynamics has been developed to support river management and restoration activities. Indicators are selected to represent key hydromorphological processes at each spatial scale, i.e., catchment, landscape unit, river segment, river reach. Their evaluation allows identification of the cascade of these processes through the spatial units and the historical changes in their propagation as a consequence of natural or human induced hydromorphological changes. The approach is deliberately open-ended so that it can be adapted to local environmental conditions and management, and it can make the most effective use of available data sets. The indicators support assessments of the current condition of the river and its catchment; past changes within the catchment and their impacts on river reaches. Therefore, they represent a sound foundation for assessing the way the catchment to reach scale units and the geomorphic units within reaches may respond to future natural changes or human interventions. The procedure is illustrated using the example of the river Frome (UK).

This research presents an analysis of river responses to flow regulation and other disturbances over time. The study was conducted in the Porma and Curueno rivers, using the hierarchical multi-scale process-based framework developed within the European REFORM Project. The characterisation of the rivers at the landscape unit, segment and reach scales under current and past conditions by different hydro-morphological indicators has provided a useful approach to (1) identify where and how main channel adjustments have occurred, (2) establish causal relationships at different scales and (3) discuss potential future scenarios and restoration strategies. Reduction of mean annual flow at the catchment scale has been observed and associated with forest expansion in the uplands. Channel narrowing, braiding reduction and riparian vegetation encroachment have occurred along both rivers, although with variable intensity among the reaches as a result of their landscape setting. Damming and flow regulation of the Porma River have been directly associated with locally accelerated narrowing, vertical bank profiles, the absence of bare gravel bars and no Salicaceae recruitment observed in certain reaches. The vertical bank profiles and the absence of in-channel bare gravel deposition forms are good indicators of sediment starvation downstream from the dam. The findings from this study suggest the importance of multi-scale approaches to assess the impacts of human-induced, short-term changes (e.g., flow regulation by dams and reservoirs) in the context of other disturbances at broader scales (e.g., climate and land cover changes) and their utility in the diagnosing problems and the proposal of restoration measures.

Summary Geomorphic responses to damming are primarily determined by the magnitude of sediment transport and sediment supply alteration and by the resulting change in the balance between the two. The former change is caused by alterations in the flow regime that are caused by reservoir operations. Flow regime changes also affect the distribution and amount of riparian vegetation that, in turn, also may enhance geomorphic responses. The latter change is caused by sediment trapping in reservoirs and by the magnitude of sediment supply from watersheds that are downstream from the dam. We examined the bio-geomorphic responses to flow regulation along a Mediterranean stream located in an agricultural area of southern Spain where there is significant fine sediment erosion from adjacent hillsides. We measured changes in active channel width and riparian corridor features during the last fifty years, based on field work and aerial photographs surveys from 1956, 1984 and 2004. We assessed the hydrological alteration and sediment delivery trends linked to dam operation and land use changes. Channel narrowing of nearly 75% and 30% reduction in total corridor area, together with average accretion rates of 0.045 m y −1 and vegetation encroachment with a 305% increase of mature forest occurred between 1956 and 2004. Causal linkages were attributed to the strong reduction of peak flows and transport capacity of flows, together with land-use changes that likely promoted increased fine sediment delivery. Vegetation overgrowth favored by increased summer flows could contribute to the narrowing and aggradation processes. Our results differ from channel responses to damming in Mediterranean regions dominated by steep gradient gravel bed rivers, and highlight the relevance of topography and land-use affecting the sediment regime downstream from the dams. We argue for a more holistic approach of water resources and land-use management at the catchment scale in order to understand the synergistic effects of dams, sediment supply, and vegetation growth, and to design appropriate flow regulation schemes to cope with irrigation demands and flood risk management in Mediterranean streams.

This is the peer reviewed version of the following article: M. GURNELL, D. CORENBLITc, D. GARCIA DE JALON, M. GONZALEZ DEL TANAGO, R. C. GRABOWSKI, M. T. O’HARE, M. SZEWCZYK (2015) A conceptual model of vegetationhydrogeomorphology interactions within river corridors. River Research and Applications (early view), which has been published in final form at 10.1002/rra.2928. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.

International audience; This paper introduces this special issue of Aquatic Sciences. It outlines a multi-scale, hierarchical framework for developing process-based understanding of catchment to reach hydromorphology that can aid design and delivery of sustainable river management solutions. The framework was developed within the REFORM (REstoring rivers FOR effective catchment Management) project, funded by the European Union’s FP7 Programme. Specific aspects of this ‘REFORM framework’ and some applications are presented in other papers in this special issue. The REFORM framework is founded on previous hierarchical frameworks, sixteen examples of which are reviewed. However, the REFORM framework has some particular properties that reflect the European context for which it was developed. The framework delineates regional landscapes into nested spatial units at catchment, landscape unit, segment, reach, geomorphic unit and finer scales. Reaches, regardless of their 'naturalness’, are assigned to a river type based on valley confinement, planform and bed material. Indicators are quantified at each spatial scale to feed three groups of assessments. First, contemporary indicators at reach and geomorphic unit scales investigate present processes, forms and human pressures within each reach. These feed assessments of present reach hydromorphological function/alteration, including whether the reach is functioning appropriately for its type; riparian corridor function and alteration; and hydromorphological adjustment. Second, indicators at catchment to segment scales investigate water and sediment production and delivery to reaches and how these are affected by human pressures now and in the past. These are used to construct an inventory of changes over space and time. Third, historical reach and geomorphic unit scale indicators are used to construct the trajectory of reach-scale changes. Contemporary reach-scale assessments, space–time inventory, and trajectory of changes are then combined to establish how river reaches of different type, subject to different human pressures, and located in different environmental contexts behave in response to changes at all considered spatial scales. These support forecasts of the likely responses of reaches to future scenarios (e.g., changes in climate, land cover, channel interventions).

[EN] Microhabitat use by three endemic Iberian cyprinids, Barbus bocagei (Steindachner), Pseudochondrostoma polylepis (Steindachner), and Squalius pyrenaicus (Gu¿ nther) was studied in terms of depth, mean water column velocity, focal height, focal velocity, distance to shore and substrate. Data were obtained by snorkelling during spring and summer at nine sites of the Tagus River Basin, Spain. Habitat suitability criteria (HSC) were calculated, including fish position and focal velocity in the water column. Species comparison showed differences in depth and focal height (indicating a vertical segregation), and greater water velocities for Pseudochondrostoma. Size-class comparisons mainly showed differences in depth and focal height (correlated with fish size). The fish groups (3 species · 3 length classes) were assigned to microhabitat functional types. The results are essential for environmental flow assessments and allow 2- and 3-dimensional habitat simulations in Mediterranean rivers; they are also useful to define critical habitats for the conservation of native fish populations, The authors acknowledge the field assistance of Esther Naveiro, Marta Morillo, Amador JimEnez, Barbara GutiErrez, Charo Sendin, MO Jesus Montenegro, MO Mar Dominguez, Julio Luruena, Ezequiel Garcia and Carlos Alonso and M. Marchamalo (Universidad PolitEcnica de Madrid). Juan Diego Alcaraz, Aina B. Hernandez, Matias Peredo and Vicent Estruch Fuster (Int. Inv. para la Gestion Integrada de Zonas Costeras, U.P.V., Spain) are thanked for assistance in data analysis. This study was supported by the Comision Interministerial de Ciencia y Tecnologia - CICYT (Project AMB 95-0914) of the Spanish Government.

The operation of small hydroelectric dams built on mountain streams induce changes in stream flow regimes that are manifested not only in the intensity of flow events, but also in the variability and frequency of high- and low-flow episodes. Former studies have shown the influence of flow variability upon the dynamics of a resident brown trout population, especially that related to the stream flow regime during spawning, incubation and emerging periods. As these life-stages are known to determine the population dynamics in further ages, stream flow variability appears to be a major influence on the regulation of a wild brown trout population. Thus, mean flow discharge should not be the only parameter taken into account when establishing ecological flow regimes to support rehabilitation of degraded trout populations in mountain streams. Ecological stream flow regime characteristics are proposed as a basis for the design of environmental flow regimes in mountain reaches downstream of hydroelectric or water supply dams. Case studies were conducted in a high mountain basin in Central Spain (River Tormes) for a period of 5 years showing that relationship between duration and frequency of high and low flow episodes during egg incubation could be linked to young-of-the-year recruitment and quantified in terms of flow management units. Duration and frequency of flow discharges could be manipulated so as to create favourable hydrological conditions for restoring sustainable populations of brown trout in rivers affected by flow regulation

The spawning period of brown trout (Salmo trutta L.) was studied in the river Castril, southern Spain, by means of redd counts. This mountain stream is located near to the southern limit of the species' natural distribution range and it shows a highly unpredictable flow regime. The spawning period extended from December to mid-April and the maximum reproductive activity was in February. These results represent the latest reproduction date and the longest spawning period reported in the literature along the natural distribution range of the species. However, belated spawning in the Castril is congruent with the known latitudinal cline: the lower the latitude, the later the spawning period. Our results, along with a review of the literature on natural populations, also showed that the duration of reproduction is the longer, the lower the latitude. Spawning lasted twice as long in the main stem of the river, which is connected with a reservoir, than in the isolated reaches. These differences may be linked to the influence of the reservoir and to habitat fragmentation. We discuss and support the hypothesis that a long spawning period is an advantage for survival in unpredictable habitats. The belated and protracted spawning period found in river Castril has important implications in fisheries management. A strong research effort is needed in order to fill the critical lack of data on southern brown trout populations.

The Cernadilla reservoir, located on the River Tera (northwest Spain, Duero Basin) is an oligotrophic reservoir with a capacity of more than 250 × 106m3 and a depth of 70 m. The regulated flow pattern is characterized by higher summer flows, higher day flows than night ones, and lower weekend flows. The effects of this artificial flow regime on the stream ecosystem were evaluated by comparing the aquatic communities of an upstream station with those of three downstream stations, located at 1, 8, and 24 km from the dam. Physiocochemical characteristics of the water, fish and macrobenthic communities, and macrophytes were studied at each station. Summer water temperatures were significantly lower downstream of the reservoir. Macrophyte biomass, macrobenthic diversity, and richness were reduced below the dam. The trophic structure was changed by an increase of shredders and grazers. Fishery total biomass greatly fluctuated seasonally, but was higher above the reservoir than below it. However, in spring the trout populations were higher upstream because large numbers of spawning cyprinids from the reservoir invaded upstream reaches of the River Tera and displayed resident trout populations.

The metabolism and kinetics of renal elimination of N-(2-picolyl)-, N-(3-picolyl)- and N-(4-picolyl)-3,5-dimethylbenzamides were studied. These products have a depressive activity on the central nervous system, as well as an anti-inflammatory and spasmolytic activity. The elimination of the products N-(3-picolyl)- and N-(4-picolyl)-3,5-dimethylbenzamides includes a process of metabolic oxidization of the atom of pyridinic nitrogen with formation of the corresponding N-oxides as main products of its bio-transformation. The process of N-oxidization was not observed with the product N-(2-picolyl)-3,5-dimethyl-benzamide. The results showed that the renal elimination rate of the products studied is greater as the pyridinic nitrogen moves away from the amide group. In the biotransformation process of these products, there is an opposite effect, i.e., the formation of corresponding N-oxides is lower as the pyridinic nitrogen approaches the amide group.