Contact CEH NORA team at noraceh@ceh.ac.ukThe NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. 1The following paper is the final version prior to publication on 22 September 2015. are proposed, the way in which indicators could contribute to classification is discussed. All of the methods described in Table 1 consider a hierarchy of spatial units, but the degree to which they develop the other aspects of the conceptual approach proposed by Frissell et al.(1986) varies widely.2. Many of the frameworks focus entirely on hydromorphological processes and forms that are either directly measured or inferred. This is because interactions between processes and forms control the dynamic morphology or behaviour of rivers and their mosaics of habitats.Hydromorphological processes drive longitudinal and lateral connectivity within river networks and corridors, the assemblage and turnover of physical habitats, and the sedimentary and vegetation structures associated with those habitats.3. Some frameworks are conceptual, providing a way of thinking about or structuring analyses of river systems, and interpreting their processes, morphology and function (e.g. Frissell et al., 1986;Habersack, 2000;Fausch et al., 2002;Thorp et al., 2006;Beechie et al., 2010;McCluney et al., 2014). Some frameworks are more quantitative, generating one or more indices or classifications of spatial units that support assessment of river systems (e.g. Rosgen, 1994;González del Tánago and García de Jalón, 2004;Merovich et al., 2013;Rinaldi et al., 2013Rinaldi et al., , 2015a MacDonald, 2002;Brierley and Fryirs, 2005;Beechie et al., 2010; Rinaldi et al., 2013a Rinaldi et al., , 2015.In some cases, theoretical or historical analyses or consideration of specific future scenarios are used to develop space-time understanding that can support management decisionmaking (e.g. Buffington, 1997, 1998;Montgomery and MacDonald, 2002;Benda et al., 2004;Brierley and Fryirs, 2005;McCluney et al., 2014 , 1997, 1998Montgomery and MacDonald, 2002;Benda et al., 2004;Brierley and Fryirs, 2005;Merovich et al., 2013;Rinaldi et al., 2013Rinaldi et al., , 2015a. Furthermore, some of the frameworks include indicators of human pressures and their impacts (e.g. Merovich et al., 2013;McCluney et al., 2014;Rinaldi et al., 2013Rinaldi et al., , 2015a.6. Finally, although most frameworks could be described as incorporating processes to some degree, some methods are particularly process-based, even when processes are inferred from forms and associations rather than being quantified by direct measurements.Frameworks that consider temporal dynamics and trajectories of historical change (see point 4, above) are particularly effective in developing understanding of processes and the impacts of changed processes cascading through time and across spatial scales.Although the list of frameworks presented in Table 1 is far from comprehensive, ...
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.
Climate change is expected to alter temperatures and precipitation patterns, affecting river flows and hence riparian corridors. In this context we have explored the potential evolution of riparian corridors under a dryness gradient of flow regimes associated with climate change in a Mediterranean river. We have applied an advanced bio‐hydromorphodynamic model incorporating interactions between hydro‐morphodynamics and vegetation. Five scenarios, representing drier conditions and more extreme events, and an additional reference scenario without climate change, have been designed and extended until the year 2100. The vegetation model assesses colonization, growth and mortality of Salicaceae species. We analysed the lower course of the Curueño River, a free flowing gravel bed river (NW Spain), as a representative case study of the Mediterranean region. Modelling results reveal that climate change will affect both channel morphology and riparian vegetation in terms of cover, age distribution and mortality. Reciprocal interactions between flow conditions and riparian species as bio‐engineers are predicted to promote channel narrowing, which becomes more pronounced as dryness increases. Reductions in seedling cover and increases in sapling and mature forest cover are predicted for all climate change scenarios compared with the reference scenario, and the suitable area for vegetation development declines and shifts towards lower floodplain elevations. Climate change also leads to younger vegetation becoming more subject to uprooting and flooding. The predicted reduction in suitable establishment areas and the narrowing of vegetated belts threatens the persistence of the current riparian community. This study highlights the usefulness of advanced bio‐hydromorphodynamic modelling for assessing climate change effects on fluvial landscapes. It also illustrates the need to consider climate change in river management to identify appropriate adaptation measures for riparian ecosystems. Copyright © 2018 John Wiley & Sons, Ltd.
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