Articles | Volume 18, issue 6
Hydrol. Earth Syst. Sci., 18, 2449–2462, 2014
Hydrol. Earth Syst. Sci., 18, 2449–2462, 2014

Research article 27 Jun 2014

Research article | 27 Jun 2014

Morphological, hydrological, biogeochemical and ecological changes and challenges in river restoration – the Thur River case study

M. Schirmer1,2, J. Luster3, N. Linde4, P. Perona5, E. A. D. Mitchell6,7,8, D. A. Barry9, J. Hollender1, O. A. Cirpka10, P. Schneider1,11, T. Vogt1, D. Radny1, and E. Durisch-Kaiser1,12,13 M. Schirmer et al.
  • 1Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
  • 2University of Neuchâtel, Centre for Hydrogeology and Geothermics (CHYN) 2000 Neuchâtel, Switzerland
  • 3Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) 8903 Birmensdorf, Switzerland
  • 4University of Lausanne, Institute of Earth Sciences, Applied and Environmental Geophysics Group, 1015 Lausanne, Switzerland
  • 5Ecole Polytechnique Fédérale de Lausanne (EPFL) Group AHEAD, 1015 Lausanne, Switzerland
  • 6Laboratory of Soil Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland
  • 7Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) Wetlands Research Group, 1015 Lausanne, Switzerland
  • 8Ecole Polytechnique Fédérale de Lausanne (EPFL) Laboratory of Ecological Systems, 1015 Lausanne, Switzerland
  • 9Ecole Polytechnique Fédérale de Lausanne (EPFL), Faculté de l'environnement naturel, architectural et construit (ENAC), Ecological Engineering Laboratory, 1015 Lausanne, Switzerland
  • 10University of Tübingen, Center for Applied Geoscience, 72074 Tübingen, Germany
  • 11University of Zurich, Department of Geography, C8057 Zurich, Switzerland
  • 12ETH Zurich, Institute of Biogeochemistry and Pollutant Dynamics, 8092 Zurich, Switzerland
  • 13Cantonal Agency for the Environment, AWEL, 8090 Zurich, Switzerland

Abstract. River restoration can enhance river dynamics, environmental heterogeneity and biodiversity, but the underlying processes governing the dynamic changes need to be understood to ensure that restoration projects meet their goals, and adverse effects are prevented. In particular, we need to comprehend how hydromorphological variability quantitatively relates to ecosystem functioning and services, biodiversity as well as ground- and surface water quality in restored river corridors. This involves (i) physical processes and structural properties, determining erosion and sedimentation, as well as solute and heat transport behavior in surface water and within the subsurface; (ii) biogeochemical processes and characteristics, including the turnover of nutrients and natural water constituents; and (iii) ecological processes and indicators related to biodiversity and ecological functioning. All these aspects are interlinked, requiring an interdisciplinary investigation approach. Here, we present an overview of the recently completed RECORD (REstored CORridor Dynamics) project in which we combined physical, chemical, and biological observations with modeling at a restored river corridor of the perialpine Thur River in Switzerland. Our results show that river restoration, beyond inducing morphologic changes that reshape the river bed and banks, triggered complex spatial patterns of bank infiltration, and affected habitat type, biotic communities and biogeochemical processes. We adopted an interdisciplinary approach of monitoring the continuing changes due to restoration measures to address the following questions: How stable is the morphological variability established by restoration? Does morphological variability guarantee an improvement in biodiversity? How does morphological variability affect biogeochemical transformations in the river corridor? What are some potential adverse effects of river restoration? How is river restoration influenced by catchment-scale hydraulics and which feedbacks exist on the large scale? Beyond summarizing the major results of individual studies within the project, we show that these overarching questions could only be addressed in an interdisciplinary framework.