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Catchment map of the River Tagliamento in NE-Italy, with towns and major tributaries, and the location of the study area in the braided section near S. Pietro. The inset shows the location of the river in Italy.
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The concepts of large river systems have been advanced with limited empirical knowledge of natural systems. In particular, virually all large Alpine European rivers were trained during the 19th century. Without first hand knowledge of natural systems we lack baseline data to assess human impacts and to address restoration and conservation strategie...
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... River Tagliamento can be regarded as the last near-natural Alpine river in Europe ( Lippert et al., 1995;Ward et al., 1999). It rises in the limestone of Alps of northern Italy and flows south- ward to the Adriatic Sea (Figure 1). The river drains an area of 2,580 km 2 and is 172 km long. ...
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Citations
... Surface layer armoring on bars can also occur, meaning that the sediments beneath this layer contain finer grain-size fractions (Hey et al. 1982;Smith 1974). However, all these morphological or sedimentological trends can be disrupted by the presence of vegetated patches on the bars, which acts as a hydraulic roughness element facilitating the deposition of particularly fine sediments (Corenblit et al. 2015;Edwards et al. 1999). ...
Gravel and sandy bars constitute critical components of river channel morphology, yet their morphodynamics in large, heavily regulated rivers during periods without significant flows remain poorly understood. This study investigates changes in surface heterogeneity and sediment sizes through a two-year field monitoring program, focusing on the frontal, central, and distal sections of four bars along the Elbe River in Czechia. Despite the absence of high-flow events reaching at least a one-year recurrence interval, observable changes in surface heterogeneity and sediment sizes were noted across all bars. However, the changes did not follow a uniform pattern; individual bars and their sections exhibited varying degrees of surface sediment coarsening or fining, alongside increases or decreases in surface heterogeneity. These findings highlight the necessity for site-specific management strategies for individual bars within such human-impacted rivers, recognizing their value as ecological hotspots. Furthermore, the methodology presented in this study may serve as a blueprint for the cost-effective monitoring of bar dynamics in channelized river sections.
... Comparing erosion and deposition across vegetated and bare areas, it emerges that a slight overall net aggradation occurred in vegetated areas (blue circles in Figure 11c), as commonly expected (Bywater-Reyes et al., 2022;Camporeale et al., 2013;Edwards et al., 1999;Nanson & Beach, 1977;Osterkamp et al., 1998). However, examining erosion and deposition individually reveals that both erosion and deposition rates were lower in vegetated areas than in bare ones (diamonds vs triangles in Figure 11c). ...
In recent decades, fluvial geomorphology and ecohydraulic research have extensively used field observations, remote sensing or hydrodynamic modelling to understand river systems. This study presents an innovative approach that combines field surveys , Light Detection and Ranging (LiDAR)-based topographical and biomass analyses and model-derived hydro-morphodynamic geostatistics to examine short-term bio-geomorphological changes in the wandering gravel-bed Orco River in Italy. Our primary hypothesis is that hydro-morphological variables can be robust descriptors for riparian vegetation distribution. From a geomorphological perspective, our study confirms the prevalent wandering behaviour of the Orco River. Moreover, we identified a widening trend in braiding and anabranching sections, particularly downstream. This is evident because of hotspots of flood-induced morphological reactivation and the redistribution of sediments from the riverbed to lateral bars, resulting in a multi-thread pattern. Our analysis reveals a net increase in biomass during the observation period despite frequent flood disturbances. We attributed it to two opposing bio-geomorphological dynamics: the reduced flow disturbance in some regions due to flood-induced geomorphological changes and the self-healing of lateral connectivity through river wandering. Such a net increase indicates that transitional rivers store carbon in the form of vegetation biomass due to their short-term morphological instability and the different timescales between vegetation and morphological adjustments. Finally, we supported our initial hypothesis with three key findings: (i) a signature of vegetation not just on topography but also on hydro-morphological conditions, summarised by inundation probability; (ii) the lower variance in vertical topographical changes in vegetated areas compared with bare ones; and (iii) the introduction of a new parameter, named inundation viscosity, derived from the prod
... Certain plant species and assemblages have a profound and lasting impact on the structure and function of riparian ecosystems by modulating matter and energy fluxes and modifying substrate cohesion (Gurnell et al., 2012). Riparian plant species (e.g., the black poplar Populus nigra L. in the Northern hemisphere) that significantly affect hydrogeomorphological processes and fluvial landforms have been identified as ecosystem engineers (sensu Jones et al., 1994), keystone species (sensu Paine, 1966), and, more recently, as potential niche constructors sensu Odling-Smee et al. (2003) (Edwards et al., 1999;Gurnell and Petts, 2006;Corenblit et al., 2009b;Francis et al., 2009). ...
Research in fluvial biogeomorphology largely aims to promote our understanding of the interactions between riparian vegetation and fluvial morphodynamics within riverine ecosystems. Starting at the end of last century, Angela M. Gurnell has made a major contribution to fluvial geomorphology by considering, in addition to water flow and sediment transport, explicitly riparian, and later also aquatic vegetation and thus significantly promoted the fluvial biogeomorphological approach from its beginnings until today. The objective of the present paper is to present a set of studies and results obtained over the last twenty years by the authors and many collaborators, including Angela M. Gurnell, on a panel of French rivers: Tech, Garonne, Isère and Allier Rivers. In particular, feedback mechanisms between fluvial morphodynamics and riparian vegetation dynamics were investigated directly in the field and also using high resolution remote sensing at the scale of individual plants, populations, communities and landscapes, as well as during semi-controlled ex situ experiments at the scale of individual plants. Collectively, the authors’ research conducted over the past 20 years contributed to elucidate some key aspects of the feedback dynamics between the lowest and highest levels of the riparian ecosystem organisation. This article presents and discusses those key aspects. The gradually obtained results contributed to better understand and quantify feedbacks between river morphodynamics and vegetation at nested spatiotemporal scales, from plant species traits to the riverine landscape. Furthermore, the biogeomorphological approach advocated for more than twenty years now, has clearly helped to contribute to the enlargement of the discipline of geomorphology to ecology as well as evolutionary ecology, and to the development of a more integrative vision to study earth surface processes.
... Many previous studies have focused on fluvial systems that maintain stream islands by addressing the need to understand aquatic ecology ecosystem functioning (e.g., Osterkamp, 1998;Edwards et al., 1999;Gurnell and Petts, 2002;Tockner et al., 2003;Karaus et al., 2005;Francis et al., 2009). Recent research has also highlighted the important role of feedback between organisms and physical processes in determining the spatial structure and dynamics of ecosystems, both terrestrial and aquatic (Francis et al., 2009). ...
Most literature on geomorphology, hydraulics, or stream ecology contained either no mention or a brief description of stream islands, the process, the development, or the ecological advantages provided. Due to a lack of information, research, and related data, there were no stream island indexes available to indicate the stream island status. Motivated by this fact, the objective of this study is to develop a conceptual design for a Stream Island Index (SII) as a template for physical habitat complexity assessment in stream restoration projects. Specific purposes included: 1) to examine stream island conceptual models; 2) to develop obvious and comprehensive explanations for stream island development by considering attributes from the geomorphic, hydraulic, and ecological perspectives. This study used the AHP method for screening and selecting attributes, transforming and developing sub-indices, assigning weights, and formulating an index. The conclusion is an SII that combines the measures of selected physical habitat quality indicators to produce a single dimensionless number, and a novel approach to communicate information on stream island quality status to the public and related policymakers. It seems essential that a serious attempt be developed to design a system that can identify the overall stream island condition. Once a generalized stream island system is set up as a controlling framework, supplementary indexes for specific purposes and locations can be added. Therefore, the SII is a promising new tool for stream restoration practitioners, and it has the potential to make a significant contribution to improving the success of stream restoration projects.
... Instream processes, which are driven by reciprocal dynamic relationships between river components, and offstream processes have been studied by several reserachers (e.g., Latrubesse and Stevaux, 2015;Leli, 2018;Leli et al., 2020). Edwards et al. (1999) pointed out that the incipience of midchannel islands remarkably ...
Midchannel islands (MCIs) are instream geomorphic units generally emerge in lowland rivers. Despite their significant ecomorphological services in the river ecosystem, the flow patterns around these self-forming riparian landforms and their impacts on aquatic life are not fully understood yet. Understanding the flow pattern around these formations enables practitioners to produce cost-effective, sustainable, and eco-friendly river management projects and strategies, forming the motivation of this study. Herein, the secondary flow pattern around MCIs was analyzed by employing a RANS-based numerical model. Flow around the simplified bodies was simulated to give a more precise analysis regarding flow-island interactions. Once the numerical validation process was completed for the cylinder using an experimental dataset, the validated model was implemented for islands (streamlined island, vertically sloped island (VSI), and realistically sloped island (RSI)). Analysis of the model results revealed the following key findings: 1) the RSI acted like a streamlined object and produced weaker lee-wake vortices with a longer recovery distance compared to the streamlined island and the VSI, 2) the RSI gained a better-streamlined form near the bed than near the water surface due to enhanced elongation, 3) this situation in the RSI case generated highly variable flow patterns along the depth behind the MCI, and 4) due to the three-dimensional geometry of the RSI, the generated large-scale vortices propagated asymmetrically towards the sides of the channel rather than remaining around the centerline.
... islands (Edwards et al., 1999;Gurnell & Bertoldi, 2020). Pioneer islands can provide shelter for further vegetation development and sediment retention, and can result in larger forested island development or floodplain extension (Gurnell & Bertoldi, 2020). ...
Since the late 1980s and early 1990s, wood reintroduction has been a commonly assessed stream restoration technique. Many of the efforts have focused on short‐term, localized physical changes and response of salmonids to wood reintroduction. Few have examined how long‐term, spatially extensive increases in wood loadings alter stream channel morphology and the geomorphic processes responsible for these changes. We used before and after photos as well as a wood storage survey with tagged restoration logs in a small, low‐elevation Western Washington watershed to characterize the effects of 23 years of wood additions. In the ~6 kilometers of wood placement we saw an increase in wood loading and channel‐spanning logjams, which contributed to deeper and more frequent pools, a reduction in particle size, increases in sediment storage, reduced stream width, vegetation re‐establishment in the riparian zone, and increased development and maintenance of floodplain channels. The largest geomorphic changes occurred due to restoration wood effectively storing pieces moving downstream. These findings imply that the cumulative habitat restoration actions and associated changes to stream habitat conditions are identifiable through comparison of historical and current photos as well as more quantitative habitat metrics. It also demonstrates that wood placement that simulates the function of large key, stable pieces accelerates habitat recovery within basins subjected to historic logging.
... Moreover, flooding disturbances create a dynamic mosaic of habitats of various successional ages (Thorp et al., 2006;Bendix and Stella, 2013;Guyon and Battaglia, 2018). Seedling establishment of many tree and shrub species is directly associated with new gravel bars, where willows and poplars will establish on riverbanks flooded often and for as long as a month at a time (i.e., willow-poplar also known as softwood floodplain forests; Edwards et al., 1999;Dixon, 2003;Lytle and Merritt, 2004;Turner et al., 2004). Meanwhile, hardwood floodplain forests are associated with more elevated areas that are flooded less often and only briefly, during peaks of flooding (Douda et al., 2016). ...
Floodplain forests offer a diversity of habitats and resources for a very wide range of plant and animal species. They also offer many benefits to humankind and are considered essential to the mitigation of the effects of climate change. Nevertheless, throughout the world they are suffering the most intense of anthropogenic pressures so are, of all ecosystems, among the most endangered. Here, we bring together and synthesise existing ecological understanding of the mechanisms underlying the high heterogeneity and diversity of temperate floodplain forests and of the pressures threatening their high biological value due to habitat homogenisation. Floodplain forests depend on the periodic disturbances under which they evolved, including fluvial dynamics, traditional management practices and the activities of herbivores. However, they have been heavily degraded by climate change, invasion of exotic species, river-flow regulation, landscape fragmentation, eutrophication and the cessation of traditional management. We can now observe two general trends in temperate floodplain forests: (1) Due to intensive landscape exploitation, they are now more open and thus prone to the spread of competitive species, including of invasive exotics and (2) Due to the cessation of traditional management, along with modified hydrological conditions, they are composed of species in the later successional stages (i.e., more shade-tolerant and mesic) while light-demanding species are quickly vanishing. Restoration practices have brought about contrasting results when restoration of floodplains to their natural states has been problematic. This is likely because of interplay between various natural and artificial processes not previously taken into proper consideration. We would like to draw attention to the fact that restoration projects or the preservation of existing floodplain forest ecosystems should combine the restoration of watercourses with the mitigation of other important threats acting at different scales of the landscape (spread of invasive species, eutrophication of watersheds and inappropriate forest management).
... There is a rich body of literature documenting the impact of hydromorphology on vegetation (Naiman and Décamps, 1997;Tabacchi et al., 1998;Edwards et al., 1999;Bendix and Hupp, 2000;Amoros and Bornette, 2002;Karrenberg et al., 2002Karrenberg et al., , 2003Naiman et al., 2005;Bornette et al., 2008;Tockner et al., 2010). For instance, Populus and Salix have been identified as dominant genera within the zone regularly disturbed by floods. ...
In the arid and semi-arid climate of Central Asia, the endorheic rivers and their ecosystems play a crucial role as regional hotspots of biodiversity and for the provision of ecosystem services for local people. The Naryn River in Kyrgyzstan as the object of interest of this thesis is one of these rivers. On a flow length of more than 600 km, it is still in a widely natural condition making it an interesting study object in a world where most large rivers are distorted by anthropogenic activities. Despite this relevance, no comprehensive scientific studies are available about the Naryn River except water resource related research. In particular, large scale information about the structure and functioning of the Naryn River system from an interdisciplinary perspective is missing. Against this background, this thesis aims to fill the research gap and deliver up-to-date information about the Naryn River corridor with a special focus on biogeomorphology, i.e. the dynamic interaction between hydromorphology and vegetation. First, this thesis delivers the necessary background information about the Naryn River corridor including a general overview, an assessment of ecosystem services, a field based overview of the structure of the riparian ecosystems and an in-depth analysis of hydrology. Basing upon this background, remote sensing methods adapted to the data-scarce environment of Central Asia are used to derive various parameters of the structure of the Naryn River on the scale from reaches to the entire river corridor. Then, the large scale biogeomorphological structures and dynamics are assessed based on dense time series of multispectral satellite imagery. From the results, it becomes obvious that the structure of the corridor of the Naryn River is heterogeneous and mainly controlled by geological contraints. Only in a laterally unconfined segment, dynamic braided river reaches can form. In these reaches, the majority of biogeomorphological interactions take place. The outcome of this thesis is on the one hand the provision of large scale and up-to-date information about the structure and functioning of the Naryn River corridor as a basis for further research or decision making. On the other hand, this thesis presents innovative remote sensing methods for large scale characterization of river corridors. In particular, an approach for the characterization of dynamic processes of biogeomorphological interactions on a large scale is developed based on time series analysis of satellite imagery. This approach can complement biogeomorphological research on smaller spatial scales by delivering spatially and temporally continuous information for entire river corridors. This has the potential to obtain new insights of the processes and emergence of structure in river systems across multiple scales.
... Whilst many academics and practitioners give attention to islander correlational worldviews and practices, Anthropocene work has also focused upon island dynamics themselves as a correlational practice. In order to demonstrate the wide-reaching power of thinking with islands, here we expand the ways in which island dynamics are being engaged by turning to ways in which ecosystems, such as forests, can be thought in terms of island dynamics (Burgess and Sharpe, 1981;Howe, 1984;Small and Hunter, 1988;Rolstad, 1991;Bierregaard Jr et al, 1992;Iida and Nakashizuka, 1995;Edwards et al, 1999). A good example of this is Eduardo Kohn's How Forests Think (2013). ...
Complete Book of 'Anthropocene Islands: Entangled Worlds'
The island has become a key figure of the Anthropocene – an epoch in which human entanglements with nature come increasingly to the fore. For a long time, islands were romanticised or marginalised, seen as lacking modernity’s capacities for progress, vulnerable to the effects of catastrophic climate change and the afterlives of empire and coloniality. Today, however, the island is increasingly important for both policy-oriented and critical imaginaries that seek, more positively, to draw upon the island’s liminal and disruptive capacities, especially the relational entanglements and sensitivities its peoples and modes of life are said to exhibit.
Anthropocene Islands: Entangled Worlds explores the significant and widespread shift to working with islands for the generation of new or alternative approaches to knowledge, critique and policy practices. It explains how contemporary Anthropocene thinking takes a particular interest in islands as ‘entangled worlds’, which break down the human/nature divide of modernity and enable the generation of new or alternative approaches to ways of being (ontology) and knowing (epistemology). The book draws out core analytics which have risen to prominence (Resilience, Patchworks, Correlation and Storiation) as contemporary policy makers, scholars, critical theorists, artists, poets and activists work with islands to move beyond the constraints of modern approaches. In doing so, it argues that engaging with islands has become increasingly important for the generation of some of the core frameworks of contemporary thinking and concludes with a new critical agenda for the Anthropocene.
For link to wider 'Anthropocene Islands' project see https://www.anthropoceneislands.online/
... Whilst many academics and practitioners give attention to islander correlational worldviews and practices, Anthropocene work has also focused upon island dynamics themselves as a correlational practice. In order to demonstrate the wide-reaching power of thinking with islands, here we expand the ways in which island dynamics are being engaged by turning to ways in which ecosystems, such as forests, can be thought in terms of island dynamics (Burgess and Sharpe, 1981;Howe, 1984;Small and Hunter, 1988;Rolstad, 1991;Bierregaard Jr et al, 1992;Iida and Nakashizuka, 1995;Edwards et al, 1999). A good example of this is Eduardo Kohn's How Forests Think (2013). ...
The island has become a key figure of the Anthropocene – an epoch in which human entanglements with nature come increasingly to the fore. For a long time, islands were romanticised or marginalised, seen as lacking modernity’s capacities for progress, vulnerable to the effects of catastrophic climate change and the afterlives of empire and coloniality. Today, however, the island is increasingly important for both policy-oriented and critical imaginaries that seek, more positively, to draw upon the island’s liminal and disruptive capacities, especially the relational entanglements and sensitivities its peoples and modes of life are said to exhibit. Anthropocene Islands: Entangled Worlds explores the significant and widespread shift to working with islands for the generation of new or alternative approaches to knowledge, critique and policy practices. It explains how contemporary Anthropocene thinking takes a particular interest in islands as ‘entangled worlds’, which break down the human/nature divide of modernity and enable the generation of new or alternative approaches to ways of being (ontology) and knowing (epistemology). The book draws out core analytics which have risen to prominence (Resilience, Patchworks, Correlation and Storiation) as contemporary policy makers, scholars, critical theorists, artists, poets and activists work with islands to move beyond the constraints of modern approaches. In doing so, it argues that engaging with islands has become increasingly important for the generation of some of the core frameworks of contemporary thinking and concludes with a new critical agenda for the Anthropocene.
