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  • 1
    In: International Review of Hydrobiology, Wiley, Vol. 107, No. 1-2 ( 2022-03), p. 9-21
    Abstract: Over the last 40 years, a growing number of restoration projects have been implemented to improve the ecological conditions of highly degraded rivers and their floodplains. Despite considerable investment in these projects, information is still limited about the effectiveness and the success of such river restoration measures, mainly due to a lack of standardised and interdisciplinary assessment approaches. During the project ‘Wilde Mulde—Restoration of a dynamic riverine landscape in Central Germany’, we implemented hydromorphological restoration measures (installation of large wood, removal of rip‐rap, reconnection of a former river side‐arm) along a lowland river in Central Germany. We carried out intensive scientific monitoring of biodiversity, hydromorphology, ecosystem functions and services, as well as socio‐economic aspects. A Before/After‐Control/Impact (BACI) design was used to identify the spatial and temporal effects of the restoration measures and to distinguish them from changes caused by background variation. For this, we used a comprehensive set of indicators, including abiotic (flow velocity, diversity of riverbed topography, and flow resistance), biological (ecosystem respiration, macroinvertebrates, fish, carabids, vegetation, and birds) and socio‐economic (acceptance and public awareness) indicators as well as the ecosystem service indicator aesthetic quality of the landscape. To meet the inherent challenges of such a large‐scale field experiment, like unpredictable environmental conditions, we used an experimental approach that allowed us to demonstrate a measurable success of the implemented restoration measures. The majority of the abiotic and some of the biological and socio‐economic indicators at the restored sites approached values of a natural reference site while already deviating from values of a nonnatural reference site two years after restoration. In addition to the applied interdisciplinary approach, multiple scales of field investigations and data analyses are essential as key components for evaluating successful river and floodplain restoration projects.
    Type of Medium: Online Resource
    ISSN: 1434-2944 , 1522-2632
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 2006634-X
    detail.hit.zdb_id: 1420232-3
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Informa UK Limited ; 2009
    In:  Journal of Hydraulic Research Vol. 47, No. 3 ( 2009-05), p. 384-386
    In: Journal of Hydraulic Research, Informa UK Limited, Vol. 47, No. 3 ( 2009-05), p. 384-386
    Type of Medium: Online Resource
    ISSN: 0022-1686 , 1814-2079
    Language: English
    Publisher: Informa UK Limited
    Publication Date: 2009
    detail.hit.zdb_id: 2488893-X
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  • 3
    Online Resource
    Online Resource
    Wiley ; 2022
    In:  International Review of Hydrobiology Vol. 107, No. 1-2 ( 2022-03), p. 22-33
    In: International Review of Hydrobiology, Wiley, Vol. 107, No. 1-2 ( 2022-03), p. 22-33
    Abstract: Large wood structures, such as wood fragments, debris jams, or entire trees, create flow and habitat diversity in rivers. A key flow feature associated with such structures is the wake, characterised by a core zone of reduced velocity and shear layers at its margins. Wakes are largely controlled by geometric and structural properties of the wood. In the present study, the flow patterns and turbulence created by different wood structures were compared at two study sites: naturally eroded and fragmented oaks (Site A) and artificial poplar installations (Site B). Flow and turbulence were quantified using pointwise velocity measurements with acoustic Doppler velocimeters (ADVs) and surface particle tracking velocimetry (SPTV). The measured flow patterns exhibited similarities with shallow porous wakes that feature fluid advection through the structure into the wake core downstream. Two additional features of wood structures were identified in the present study: (i) the growth of the shear layers was hindered by bed friction like for shallow mixing layers and (ii) the presence of a tree stem and sediment deposit in the wake centre delayed or even suppressed the interaction of the shear layers and vortex street formation similar to a wake‐splitter plate. Methodologically, the combined ADV/SPTV measurement approach and the use of analytical models for shallow mixing layers proved to be highly valuable to decipher the complex flow patterns around wood structures in the field.
    Type of Medium: Online Resource
    ISSN: 1434-2944 , 1522-2632
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 2006634-X
    detail.hit.zdb_id: 1420232-3
    SSG: 12
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  • 4
    In: Freshwater Biology, Wiley, Vol. 57, No. 12 ( 2012-12), p. 2425-2435
    Type of Medium: Online Resource
    ISSN: 0046-5070
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2012
    detail.hit.zdb_id: 2020306-8
    detail.hit.zdb_id: 121180-8
    SSG: 12
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  • 5
    In: International Review of Hydrobiology, Wiley, Vol. 107, No. 1-2 ( 2022-03), p. 34-45
    Abstract: Large wood (LW) is an integral part of natural river ecosystems and determines their ecological integrity by modulating hydromorphology and providing habitats. Hence, LW installations are a common restoration measure in large rivers, even if effects on biodiversity are ambiguous or unknown for ecosystem functioning. Here we quantified the hydromorphological, biological, and functional effects of LW 8 months after installation in a large gravel‐bed river. Both morphological and flow diversity increased strongly by 821% and 127%, respectively. Similarly, fish abundance increased nearly 10‐fold, and macroinvertebrate diversity increased by 35%. Ecosystem functions benefited from LW installation and increased significantly (e.g., by up to 390% for bacterial production) at sites influenced by LW compared to those without LW. Our results highlight the role of the bark habitat of LW that increased the direct effects of LW via the provision of new habitat and stimulated ecosystem‐wide processes. Our integrative approach evaluating the success of LW installations in a large river revealed cascading effects from the provisioning of new habitats, the increase of species diversity to higher ecosystem functioning. It also demonstrated that hydromorphological parameters or community composition alone are insufficient to quantify the complex effects of LW installation, which underlines the necessity to evaluate restoration success with different measures.
    Type of Medium: Online Resource
    ISSN: 1434-2944 , 1522-2632
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 2006634-X
    detail.hit.zdb_id: 1420232-3
    SSG: 12
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  • 6
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2009
    In:  Aquatic Sciences Vol. 71, No. 3 ( 2009-10), p. 318-330
    In: Aquatic Sciences, Springer Science and Business Media LLC, Vol. 71, No. 3 ( 2009-10), p. 318-330
    Type of Medium: Online Resource
    ISSN: 1015-1621 , 1420-9055
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2009
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    detail.hit.zdb_id: 1464021-1
    SSG: 12
    SSG: 21,3
    SSG: 13
    SSG: 14
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  • 7
    Online Resource
    Online Resource
    American Geophysical Union (AGU) ; 2010
    In:  Water Resources Research Vol. 46, No. 11 ( 2010-11)
    In: Water Resources Research, American Geophysical Union (AGU), Vol. 46, No. 11 ( 2010-11)
    Abstract: Shallow lateral shear layers forming between flows with different velocities, though essential for mixing processes in natural streams, have been examined only in laboratory settings using smooth, fixed‐bed channels. This paper reports the results of an experimental study of a shear layer in a straight reach of a natural river where the layer, in contrast to the two‐dimensional structure observed in the laboratory, is highly three‐dimensional. The study included pronounced transverse pressure gradients, which influenced shear layer structure compared to flume experiments. It also introduces an analysis that complements conventional theory on mixing layers. The lateral velocity gradient between the flows downstream from a splitter plate placed in the river, the principal controlling factor, was adjusted for three experimental runs to determine the influence of different gradients on shear‐layer dynamics. In each run, detailed three‐dimensional measurements of mean and turbulent characteristics were obtained at five cross sections downstream from the splitter plate. Although experimental results agreed with conventional mixing‐layer theories with respect to turbulence, the dynamics of the shear layers were dominated by the mean lateral fluxes of momentum. After re‐examining the governing equations, we developed a parabolic equation describing the shear layer evolution and several scaling relations for essential terms of the energy budget: mean and turbulent lateral fluxes of momentum, turbulent kinetic energy, and dissipation rates. The study also provides insight into the spectral dynamics of turbulence in the shear layer and clarifies previous observations reported for confluences in natural streams.
    Type of Medium: Online Resource
    ISSN: 0043-1397 , 1944-7973
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2010
    detail.hit.zdb_id: 2029553-4
    detail.hit.zdb_id: 5564-5
    SSG: 13
    SSG: 14
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