Restoration of Running Waters
Restoration of Running Waters (German)
Restoration of Running Waters
Running waters from small brooks to large rivers and their floodplains are among the most biodiverse ecosystems worldwide (Ward et al. 1999, Robinson et al. 2002). This high biodiversity primarily stems from the natural habitat diversity found both within the water bodies (e.g deadwood and leaf accumulations) and from the dynamic features of the banks and floodplains. Unfortunately, rivers and floodplains across Germany are in poor condition (BMU & BfN 2021, BUMV & UBA 2022). The primary stressors affecting these ecosystems include alterations in watercourse morphology and pollution. Various political frameworks, such as the EU Water Framework Directive (WFD = WRRL) and the Federal Blue Belt Program (BBD), aim to improve the condition of water bodies (WFD) and their floodplains (BBD). As a result, many running water sections have been, and continue to be, restored during the implementation of these initiatives. The stressors on running water and floodplains occur on different spatial scales: at the level of certain river sectionor the catchment area level. Consequently, hydromorphological measures aimed at improving water and floodplain structures must address these scales accordingly.
Planning and implementing restoration measures involve several steps: defining planning objectives, securing fundings, securing land, conducting planning and permitting processes, implementing the physical restoration, and ideally, conducting post-project monitoring. It is essential that the process involve various authorities, as well as conservation organizations and the public, through the entire procedure (Federal Environment Agency 2019).
Several studies show that creating near-natural habitats in running waters and floodplains through hydromorphological measures can have positive effects on the fauna and flora of these ecosystems, although the responses often vary significantly across species groups. Species groups in the floodplains, such as floodplain vegetation, birds, and ground beetles, often respond quickly and noticeably, while species within the water bodies tend to show little or delayed reactions (Januschke et al. 2017, Januschke 2018, Pilotto et al. 2018). Besides the dispersal potential of species (which is more effective for floodplain species than for aquatic species), other factors like time and catchment-scale stressors can limit or enhance the success of these measures. For example, historical water quality issues originating from agricultural practices can negatively impact the entire running water system. On the positive side, nearby natural running water sections can serve as important colonization sources, potentially benefiting downstream sections through what is known as the "radiation effect (= Strahleffekt)." This concept forms the basis for planning restoration projects in some German states, such as North Rhine-Westphalia (LANUV 2011).
Two methods are available for assessing the biocenotic success of hydromorphological measures. The LAWA method, by Pottgiesser et al. (2020) offers guidelines for evaluating aquatic habitats based on data regarding the structural quality of flowing waters and biological components (macrozoobenthos, fish, macrophytes) running in line with Water Framework Directive standards. The method by Januschke et al. (2021) supports biocenotic monitoring along riverbanks and in floodplains, assessing habitat structures and various species groups, including amphibians, vascular plants, terrestrial and aquatic mollusks, ground beetles, and birds.
Photo Gallery
Sources
BMU (Federal Ministry for the Environment, Nature Conservation and Nuclear Safety) & BfN (Federal Agency for Nature Conservation) (2021): Floodplain Status Report 2021 – River Floodplains in Germany. Bonn. 72 pp.
BMUV (Federal Ministry for the Environment, Nature Conservation, Building, Nuclear Safety, and Consumer Protection) & UBA (Federal Environment Agency) (2022): The Water Framework Directive - Germany's Water Bodies 2021. Progress and Challenges. Bonn, Dessau. 124 pp.
Januschke, K. (2018): Effects of River Restoration on Aquatic and Terrestrial Organism Groups. Applied Carabidology 12 (2018): 37–47.
Januschke, K., G. Ledesma-Krist, M. Scholz, M. Gelhaus, B. Stammel & D. Hering (2017): Metadata - Current Stock for Monitoring in Floodplains. In: Schneider, E., Werling, M., Stammel, B., Januschke, K., Ledesma-Krist, G., Scholz, M., Hering, D., Gelhaus, M., Dister, E. & G. Egger (Eds.): Biodiversity of River Floodplains in Germany. Federal Agency for Nature Conservation, Bonn Bad Godesberg. - Conservation and Biological Diversity Issue 163: 119-147. ISBN: 978-3-7843-4063-0.
Januschke, K., Hering, D., Stammel, B., Brunzel, S., Scholz, M., Rumm, A., Sattler, J., Foeckler, F., Fischer-Bedtke, C., Makiej, A. & T. Ehlert (2021): Biocenotic Floodplain Status Assessment for Monitoring Success – Floodplain Magazine, Issue 20: 20–28. Magazine of the Floodplain Center Neuburg a. d. Donau. ISSN 2190–7234.
LANUV (State Agency for Nature, Environment, and Consumer Protection North Rhine-Westphalia) (2011): Radiation and Stepping Stone Concept in Planning Practice. Recklinghausen. LANUV Working Paper 16. 99 pp.
Pilotto, F., Tonkin, J.D., Januschke, K., Lorenz, A.W., Jourdan, J., Sundermann, A., Hering, D., Stoll, S. & Haase, P. (2018): Diverging Response Patterns of Terrestrial and Aquatic Species to Hydromorphological Restoration. Conservation Biology 33: 132-141. doi: 10.1111/cobi.13176.
Pottgiesser, T., K. Januschke & A. Müller (2020): Recommendations for Monitoring the Success of Hydromorphological Measures in and along Flowing Waters – Handbook. LAWA Project O 8.18. 116 pp.
Robinson, C. T., Tockner, K., & Ward, J. V. (2002). The Fauna of Dynamic Riverine Landscapes. Freshwater Biology 47(4): 661–677.
Ward, J. V., Tockner, K., & Schiemer, F. (1999): Biodiversity of Floodplain River Ecosystems: Ecotones and Connectivity. Regul. Rivers: Res. Mgmt. 15: 125–139.