La dynamique sédimentaire des rivières, souvent modifiée par les aménagements, n'a pas été considérée comme un facteur significatif pour la qualité des environnements riverains et dans les stratégies de restauration. Les approches destinées à restaurer la charge sédimentaire d'une rivière afin qu'elle soit compatible avec les besoins environnementaux et humains, en termes de quantité de sédiments et de granulométrie, sont encore peu développées. De plus, les approches existantes telles que l'injection de sédiments sont souvent coûteuses et nécessitent une intervention humaine. Cette thèse porte sur l'érosion induite des berges, qui constitue une alternative plus durable pour l'environnement. Cette approche consiste à accroître le potentiel d'érosion en certains sites le long des berges d'une rivière chenalisée, en leur permettant d'être plus fortement érodés lors de crues. Deux approches, un modèle physique et des simulations numériques, ont été utilisées pour étudier un site localisé sur le Vieux-Rhin, en aval de Bâle (Suisse), où une modification des épis éxistents est prévue afin de favoriser l'érosion des berges. Dans un premier temps, différents scénarios de modification ont été testés sur une gamme de débits, au moyen d'un modèle physique à échelle de Froude non distordue avec un lit mobile. Dans ce modèle physique, un mélange de quatre classes granulométriques a été adopté afin de reproduire la courbe granulométrique mesurée en nature. Le modèle a été mis à l'échelle par une méthode spécifique qui représente avec précision le début du mouvement de chaque classe. Une stratégie efficace d'érosion des berges a été établie, qui libère des sédiments sans provoquer un retrait excessif des berges qui puisse compromettre la sécurité d'un chenal de navigation adjacent. Par la suite, l'aptitude du modèle numérique Telemac2D à modéliser l'érosion et les processus de rupture de berge a été évaluée. L'algorithme existant de rupture de berge a été modifié pour améliorer les résultats, et les développements implémentés ont été validés par des comparaisons sur des cas-tests de laboratoire. Enfin, les essais du modèle physique ont été simulés numériquement à la même échelle. Les simulations reproduisent les processus observés sur le modèle physique, et les volumes de sédiments érodés et déposés sont du même ordre de grandeur que ceux mesurés / Sediment transport dynamics, often heavily modified by river training, are not yet sufficiently considered as a significant factor in riparian environmental quality and river restoration strategies. Approaches for restoring a river's sediment in quantity and in grain size distribution, so that it is compatible with both ecological and human needs, are still under development. Furthermore, existing approaches such as direct sediment injection are often expensive and require human intervention. This thesis explores induced bank erosion, a more environmentally sustainable alternative. This approach involves increasing the potential for erosion at certain sites along the bank of a trained river, and allowing them to be eroded during high flow periods. Two modelling approaches, physical scaled models and numerical simulation, were used to study a site located on the Old Rhine downstream of Basle (Switzerland) where existing bank protection groynes will be modified to induce bank erosion. Firstly, different modification options were tested over a range of flow rates with a Froude-scaled undistorted movable-bed physical model. The physical model used a mixture of four grain sizes to reproduce the bank grain size distribution found at the site, and was scaled according to a specific method which accurately represents initiation of motion for each grain size. An effective bank erosion strategy was found that releases sediment without compromising the safety of an adjacent navigation channel through excessive bank retreat. Subsequently, the capability of the Telemac2D two-dimensional depth-averaged numerical modelling system to model bank erosion and failure processes was assessed, and the existing bank failure algorithm was modified in order to improve results. Algorithm developments were tested with two laboratory test cases. Then, the physical model tests were simulated at their same scale. Simulations reproduced the processes present in the physical model tests, and volumes of eroded and deposited sediment were of the same order of magnitude

Rivers and their catchments are under mounting pressure from direct channel modification, intensification of land use, and from a legacy of decades of channelisation. Recent legislation, in the form of the EU Water Framework Directive, places a greater emphasis on the management of water bodies as holistic systems, and includes the explicit consideration of hydromorphological quality, which describes the hydrologic and geomorphic elements of river habitats. These are defined specifically as hydrological regime, river continuity and river morphology. This appreciates that sediment and flow regimes, along with the channel structure, provides the 'template' on which stream ecological structure and function is built. Invertebrate fauna contribute significantly to the biodiversity of rivers, and often form the basis of monitoring river health. However much of the fundamental ecological knowledge base on the response of invertebrates to hydromorphological change needed to make informed decisions and accurate predictions, is either lacking, inadequate or contradictory. This thesis addresses some of the key potential shortcomings in recent bio-assessment that others have alluded to, but which have rarely been explored in the context of direct channel manipulations. By using two case studies of, realignment in a natural upland catchment, and flood protection engineering in an urban stream, this study investigates the sensitivity of hydromorphological impact assessment methods that rely on biodiversity patterns of benthic riverfly (Ephemeroptera, Plecoptera and Trichoptera) larva. This work employed widely used biomonitoring indices of benthic riverfly larva abundance, species richness, alpha and beta diversity, and community composition, applied over a range of spatial scales, in combination with spatially contemporaneous physical habitat data, to describe and explain community changes in response to disturbance, and patterns of natural variation. The effects of restoration were investigated using a high degree of sample replication within channels and across the wider catchment, as well as contrasting spring and autumn seasons. To assess change in a small urban channel, approaches that explicitly consider spatial elements of community data, using spatial eigenvectors analysis, were applied to spatially detrend community data and directly investigate spatial patterns. Restoration of the Rottal Burn was found to be successful in restoring habitat diversity and geomorphic processes, and in turn increasing reach scale species richness and beta diversity through the gradual arrival of rare and specialist taxa into novel habitats. Catchment scale replication revealed high variation in diversity indices of modified and undisturbed streams, and a strong temporal pattern related to antecedent flow conditions. Channels with greater habitat heterogeneity were able to maintain high gamma diversity during times of high flow stress by providing a number of low flow refuges along their length. The urban Brox Burn had surprisingly high riverfly richness and diversity driven by small scale hydraulic heterogeneity, created by bed roughness resulting in a range of microhabitats. Riverfly community responses to direct channel dredging could not be detected by measurements of average richness and diversity, however distinct changes were seen in gamma diversity, the identity of community members and their arrangement among sample patches. Impacts of sediment pollution release due to engineering were short lived and apparently had little detrimental impact on biodiversity. Strong spatial patterns of community assembly on the stream bed were uncovered, relating to longitudinal, edge and patchy patterns. Significant habitat drivers of community composition were confounded by high amounts of spatial autocorrelation, especially hydraulic variables. Due to the strongly physical and spatial nature of hydromorphological disturbance, turnover of species between sample locations at a range of scales, and the spatial arrangement of habitats and communities is of more use for detecting these types of subtle changes compared to mean richness or diversity. These findings have implications for the targeting of resources for monitoring of restoration, or engineering disturbances, in order to be sensitive to hydromorphological change. Efforts should target the main area of natural variability within the system, either replicating sampling in time or space to distinguish effects of impact. Spatial patterns, measures of beta diversity and species identity can be better exploited to identify systems with functioning geomorphological processes. Channel typologies proved misleading, and quantification of habitat and selection of control sites using multiple pre-defined criteria should be carried out. Studies of restoration operations and engineering impacts provide considerable opportunities for advancing our knowledge of the mechanisms that drive community response under a range of conditions to improve impact detection.

RESUMEN Los peces nativos son indicadores de la salud de los ecosistemas acuáticos, y se han convertido en un elemento de calidad clave para evaluar el estado ecológico de los ríos. La comprensión de los factores que afectan a las especies nativas de peces es importante para la gestión y conservación de los ecosistemas acuáticos. El objetivo general de esta tesis es analizar las relaciones entre variables biológicas y de hábitat (incluyendo la conectividad) a través de una variedad de escalas espaciales en los ríos Mediterráneos, con el desarrollo de herramientas de modelación para apoyar la toma de decisiones en la restauración de ríos. Esta tesis se compone de cuatro artículos. El primero tiene como objetivos modelar la relación entre un conjunto de variables ambientales y la riqueza de especies nativas (NFSR), y evaluar la eficacia de potenciales acciones de restauración para mejorar la NFSR en la cuenca del río Júcar. Para ello se aplicó un enfoque de modelación de red neuronal artificial (ANN), utilizando en la fase de entrenamiento el algoritmo Levenberg-Marquardt. Se aplicó el método de las derivadas parciales para determinar la importancia relativa de las variables ambientales. Según los resultados, el modelo de ANN combina variables que describen la calidad de ribera, la calidad del agua y el hábitat físico, y ayudó a identificar los principales factores que condicionan el patrón de distribución de la NFSR en los ríos Mediterráneos. En la segunda parte del estudio, el modelo fue utilizado para evaluar la eficacia de dos acciones de restauración en el río Júcar: la eliminación de dos azudes abandonados, con el consiguiente incremento de la proporción de corrientes. Estas simulaciones indican que la riqueza aumenta con el incremento de la longitud libre de barreras artificiales y la proporción del mesohabitat de corriente, y demostró la utilidad de las ANN como una poderosa herramienta para apoyar la toma de decisiones en el manejo y restauración ecológica de los ríos Mediterráneos. El segundo artículo tiene como objetivo determinar la importancia relativa de los dos principales factores que controlan la reducción de la riqueza de peces (NFSR), es decir, las interacciones entre las especies acuáticas, variables del hábitat (incluyendo la conectividad fluvial) y biológicas (incluidas las especies invasoras) en los ríos Júcar, Cabriel y Turia. Con este fin, tres modelos de ANN fueron analizados: el primero fue construido solamente con variables biológicas, el segundo se construyó únicamente con variables de hábitat y el tercero con la combinación de estos dos grupos de variables. Los resultados muestran que las variables de hábitat son los ¿drivers¿ más importantes para la distribución de NFSR, y demuestran la importancia ecológica de los modelos desarrollados. Los resultados de este estudio destacan la necesidad de proponer medidas de mitigación relacionadas con la mejora del hábitat (incluyendo la variabilidad de caudales en el río) como medida para conservar y restaurar los ríos Mediterráneos. El tercer artículo busca comparar la fiabilidad y relevancia ecológica de dos modelos predictivos de NFSR, basados en redes neuronales artificiales (ANN) y random forests (RF). La relevancia de las variables seleccionadas por cada modelo se evaluó a partir del conocimiento ecológico y apoyado por otras investigaciones. Los dos modelos fueron desarrollados utilizando validación cruzada k-fold y su desempeño fue evaluado a través de tres índices: el coeficiente de determinación (R2 ), el error cuadrático medio (MSE) y el coeficiente de determinación ajustado (R2 adj). Según los resultados, RF obtuvo el mejor desempeño en entrenamiento. Pero, el procedimiento de validación cruzada reveló que ambas técnicas generaron resultados similares (R2 = 68% para RF y R2 = 66% para ANN). La comparación de diferentes métodos de machine learning es muy útil para el análisis crítico de los resultados obtenidos a través de los modelos. El cuarto artículo tiene como objetivo evaluar la capacidad de las ANN para identificar los factores que afectan a la densidad y la presencia/ausencia de Luciobarbus guiraonis en la demarcación hidrográfica del Júcar. Se utilizó una red neuronal artificial multicapa de tipo feedforward (ANN) para representar relaciones no lineales entre descriptores de L. guiraonis con variables biológicas y de hábitat. El poder predictivo de los modelos se evaluó con base en el índice Kappa (k), la proporción de casos correctamente clasificados (CCI) y el área bajo la curva (AUC) característica operativa del receptor (ROC). La presencia/ausencia de L. guiraonis fue bien predicha por el modelo ANN (CCI = 87%, AUC = 0.85 y k = 0.66). La predicción de la densidad fue moderada (CCI = 62%, AUC = 0.71 y k = 0.43). Las variables más importantes que describen la presencia/ausencia fueron: radiación solar, área de drenaje y la proporción de especies exóticas de peces con un peso relativo del 27.8%, 24.53% y 13.60% respectivamente. En el modelo de densidad, las variables más importantes fueron el coeficiente de variación de los caudales medios anuales con una importancia relativa del 50.5% y la proporción de especies exóticas de peces con el 24.4%. Los modelos proporcionan información importante acerca de la relación de L. guiraonis con variables bióticas y de hábitat, este nuevo conocimiento podría utilizarse para apoyar futuros estudios y para contribuir en la toma de decisiones para la conservación y manejo de especies en los en los ríos Júcar, Cabriel y Turia. / Olaya Marín, EJ. (2013). Ecological models at fish community and species level to support effective river restoration [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/28853 / TESIS

River restoration projects are being installed worldwide to rehabilitate degraded river habitat. Many of these projects focus on stream habitat improvement (SHI), and an estimated 60%of the 37,000 projects listed in the National River Restoration Science Synthesis Program focus on SHI for salmon and trout species. These projects frequently lack a sufficient monitoring program or account for the environmental costs associated with SHI. The present study used life cycle assessment (LCA) techniques and topographic effectiveness monitoring to quantify environmental costs on the basis of geomorphic change. This methodology was a novel approach to assessing the cost-benefit relationship of SHI. To test this methodology, two phases of the Lower Scotts Creek Floodplain and Habitat Enhancement Project (LSCR) were used as a case study. The LSCR was a SHI project installed along the northern coast of Santa Cruz County, California, USA. A limited scope LCA was used to quantify the life cycle impacts of raw material production, materials transportation, and on-site construction. Once these baseline results were produced, a topographic monitoring program was used to quantify the topographic diversity index (TDI) in pre- and post-project conditions. The TDI percent change was used to scale the baseline LCA results, which quantified the environmental impacts based on geomorphic change. Phase II outperformed phase I. Phase I had greater cumulative environmental impacts and experienced a 7.7 % TDI increase from pre- to post-project conditions. Phase II had 43% less cumulative environmental impacts and experienced a 7.9% TDI increase from pre- to post-project conditions. The impacts in phase I were greater because of the amount of material excavated to create off-channel features, which were a key feature of the LSCR. A scenario analysis also was conducted within the LCA component of this study. The scenario analysis suggests that life cycle impacts could be reduced by 30%-65% by using the accelerated recruitment method in place of importing materials to build large wood complexes. The results of this study suggest that managers may improve the environmental performance of SHI projects by: (1) using the accelerated recruitment method to introduce larger key pieces to the channel, reducing the need to import materials; (2) using nursery grown plants as opposed to excavating plants for revegetation; (3) minimizing fuel combustion in heavy equipment and haul trucks by ensuring clear access to the channel and streambank, using small engine equipment to clear access corridors during site preparation, running more fuel-efficient machinery or bio-fuel powered machinery, and by attempting to minimize haul distances by sourcing materials locally; and (4) utilizing a “franken-log” design (a ballasted LWC configuration with a rootwad fastened to the downstream end of a log) in LWCs which led to favorable TDI change. This study concluded that LCA could be a valuable tool for monitoring SHI and river restoration projects and that further research of the TDI analysis is justified.

Au fil des siècles, de nombreux cours d’eau ont été régulés par des barrages pour assurer différents besoins tels que la gestion des inondations, la production d’énergie hydro-électrique, l’irrigation, l’approvisionnement en eau potable, etc. Aujourd’hui, dans le tiers nord de la planète, 77% des cours d’eau sont concernés par la présence de ces ouvrages et de très nombreux ouvrages sont en cours de construction ou prévus dans les prochaines décennies. Les impacts des barrages, notamment ceux dont les réservoirs sont les plus volumineux, sont aujourd’hui bien connus. Leur influence, plus ou moins prononcée, peut notamment affecter les crues (débits, fréquence, pointe et durée), ce qui entraine de facto une modification de l’occurrence du « débit morphogène » naturel dans les tronçons situés en aval. Il en résulte une morphologie et une dynamique fluviales modifiées, avec des Incidences sur la biologie et les usages. Afin d’améliorer, voire de restaurer le bon fonctionnement des milieux aquatiques et rivulaires, il est de plus en plus souvent demandé aux gestionnaires de barrages de générer des débits élevés, dits « morphogènes », depuis leurs ouvrages. Ce travail de thèse s’est attaché dans un premier temps à clarifier les concepts de débits, lâchers et écoulements « morphogènes ». Il a été proposé une nouvelle terminologie s’intégrant dans le contexte plus large des débits environnementaux et des débits écologiques (environmental et ecological flows). Dans un second temps, les précédents travaux et les expérimentations menées sur la Durance, la Selves et l’Isère, ont fourni des éléments pour construire une méthodologie de mise en œuvre de lâchers morphogènes dans le cadre d’une gestion adaptative. Cette méthodologie opérationnelle repose sur une série d’étapes successives découlant d’un diagnostic préalable. Elle permet de déterminer les paramètres nécessaires au dimensionnement, d’identifier les contraintes et de définir les résultats attendus (compartiments visés, ordres de grandeurs des processus, etc.) pour évaluer l’efficience de l’opération. Enfin, grâce à la mise en œuvre d’indicateurs de déclenchement, elle fournit des éléments d’évaluation pour décider de renouveler, d’améliorer ou non le lâcher. / Over the centuries, many rivers have been regulated by dams to meet various needs such as flood management, hydropower production, irrigation, drinking water supply, etc. Today, in the northern third of the planet, 77% of watercourses are affected by dams and a very large number are under construction or planned in the coming decades. The impacts of dams, particularly those with the largest reservoirs, are now well-known. Their influence, more or less pronounced, can affect floods (flow, frequency, peak and duration), which results in a change of the occurrence of the natural "channel morphing discharge" in the downstream reaches. The result is a modified river morphology and dynamics, with impacts on biological communities and uses. In order to improve/restore aquatic and riparian environments, dam managers are increasingly being asked to generate high flows, known as "flushing flows” or “ecomorphogenic flows”, from their dams.This thesis focuses initially on clarifying the concepts of discharge, water release, and "ecomorphogenic flows”. A new terminology has been proposed that fits into the broader context of “environmental flows” and “ecological flows”. In a second step, previous works and experiments carried out on the Durance River, the Selves River and the Isère River provided elements to build a methodology for implementing ecomorphogenic flow releases as part of adaptive management. This operational methodology is based on a series of successive steps resulting from a preliminary diagnosis. It makes it possible to determine the parameters necessary for designing releases, identifying constraints and defining expected results (target compartments, orders of magnitude of process, etc.) to evaluate the efficiency of the operation. Finally, through the implementation of trigger indicators, it provides evaluation information to decide whether to renew, or improve releases or to replace them with other management actions.

This thesis deals with the projection of water management and erosion control measures in the Javornický stream floodplain to improve water quality in the Rosnička pond near the town of Svitavy. In the teoretical part, the author summarized current practices in the areas of small river restorations and protection against soil erosion in the Czech Republic. In the practical part, the analasis of the area was first made, including the analysis of natural conditions, hydroecological monitoring of watercourses according to the HEM 2014 method and quantification of soil loss conditions according to the USLE method. Then, revitalization measures on the Javornický stream were designed to improve the self-purification of water and the restoration of ground water in the floodplain, as well as two variants of erosion control measures on agricultural areas to reduce the input of sediments into the hydrographic network. Finally, conceptual and technical recommendations for the implementation of these measures were formulated, as a basis for planning and decision-making of the political leadership of the town of Svitavy.

This Master’s thesis aims to fill the research gaps by providing a study that clearly defines and concretizes the social benefits in river restorations. By further analysing the significance of the social benefits the aim is further to gain a better understanding of the factors that enable people to reap greater social benefits in river restoration. Given the dearth in research, an exploratory research approach is chosen to guide this thesis, on the premises that it provides and generates greater descriptions and broader understandings of the social benefits in river restorations. In addition, the exploratory approach enables analysis and arguments using both primary and secondary research methods, which are applied through literature reviews, official website analysis and interviews with representatives of the single organizations. The factors considered to constitute the social benefits in river restoration are well-being, aesthetics, recreation, play and learn, cultural expression, social cohesion and sense of belonging. When analysing the key factors that enable people to benefit from the social benefits of river restoration, the recognition includes relational values, active citizenship, public participation, knowledge sharing and social dynamics. In addition, the data collected from the single organizations indicate different levels of citizens’ activity and participation, i.e., semi-active, participating, active and highly active. Lastly, this thesis’ contribution to the research field is of great value, as the main findings demonstrate a coherence and consistency between the theoretical reasonings and the identifications of the four single organizations.

Die Besiedlung von Gewässern durch Fische, ist neben abiotischen Lebensraumbedingungen auch von der Erreichbarkeit d.h. von der art-spezifischen Ausbreitungsfähigkeit sowie von Wanderhindernissen abhängig. Der erste Teil dieser Arbeit bietet die erste umfangreiche quantitative Analyse von Ausbreitungsmustern und -distanzen von Flussfischen. Aus der Fachliteratur wurden 160 empirische Datensätze aus 71 wissenschaftlichen Studien zur Ausbreitung von 62 Fischarten in Flüssen extrahiert und an leptokurse Wahrscheinlichkeits-Dichte-Funktionen (Dispersal kernel) angepasst. Es konnte bei Fischpopulationen zwischen einer stationären (ca. 2/3) und einer mobilen Komponente (ca. 1/3) unterschieden werden deren Ausbreitungsdistanzen von vier Faktoren abhängig sind: Fischlänge, Form der Schwanzflosse, Fließgewässergröße, betrachtete Zeitspanne. Der zweite Teil dieser Arbeit widmet sich dem neu entwickelten Fischausbreitungsmodell FIDIMO einem GIS-Softwareprogramm zur Modellierung und Simulation der räumlichen und zeitlichen Ausbreitungsmuster von Fischen in Flüssen unter Berücksichtigung von Wanderhindernissen. FIDIMO verknüpft konzeptionelle Überlegungen zu Ausbreitungsmodellen in verzweigten Fließgewässernetzwerken mit empirisch bestimmten leptokursen Fischausbreitungskurven unter ausschließlicher Verwendung von Free and Open Source Software. Im dritten Teil der Arbeit wurde FIDIMO zur Modellierung der Ausbreitung von 17 Fischarten angewendet um die Einflüsse von (i) Habitatqualität, (ii) Ausbreitungsfähigkeit und (iii) Fließgewässer-Fragmentierung auf die Besiedlungsmuster durch Fische zu bestimmen. Die Ergebnisse zeigen, dass die artspezifische Habitatqualität und Ausbreitungsfähigkeit die Besiedlung maßgeblich bestimmen. Dagegen wurde kein signifikanter Einfluss von Barrieren auf das Vorkommen einer Art gefunden. Über längere Zeiträume sinkt der Einfluss von Fischausbreitung auf das lokale Vorkommen einer Fischart während die Habitatqualität relativ wichtiger wird. / The colonisation of rivers by fishes is directly linked to abiotic habitat conditions but often impaired by dispersal abilities of fishes and movement constraints such as barriers. The first part of this thesis provides the first comprehensive quantitative analysis of freshwater fish movement while considering fish populations consisting of differently mobile specimens. 160 empirical datasets from 71 studies on the movement of 62 riverine fish species were analysed based on refitted leptokurtic probability-density functions (dispersal kernels). A share of one third and two thirds emerged as a general pattern of the mobile and stationary component of a fish population, respectively. Moreover, four variables were identified primarily determining dispersal distances: fish length, aspect ratio of the caudal fin, river size and time. In the second part of the thesis, the novel fish dispersal model FIDIMO is introduced. FIDIMO provides a GIS-tool for predicting and simulating spatio-temporal patterns of fish dispersal in dendritic river networks considering movement barriers. The fish dispersal model FIDIMO links conceptual considerations on dispersal modelling with empirically observed leptokurtic fish movement patterns and the strengths of geographically explicit modelling in Free and Open Source GIS. In the third part of the thesis, FIDIMO was applied for modelling dispersal of 17 fish species to disentangle the effects of (i) habitat suitability, (ii) dispersal constraints and (iii) network fragmentation on the distribution of river fishes. The results show significant positive effects of both, local-scale habitat quality and species-specific dispersal ability on the distribution of river fishes, whereas no significant effect of barriers influencing the presence of a species could be found. Over longer time periods the importance of dispersal decreased in favour of habitat suitability becoming relatively more relevant in determining species'' presence.

This diploma thesis deals with the problem of river restoration. Selected watercourse, which was inappropriately technically modified, had been mapped in detail and land use map was compiled. The watercourse was divided into sections, which were described in detail and assessed for suitability for restoration action. The new nature-friendly channel was designed on the selected section of the watercourse. Technical graphic documentation was designed.