RECORD - REstored CORridor Dynamics
Dates: 2008-2012
Funding: SCCER
PhD Student: Nicola Pasquale
Dissertation: research-collection
Principal Investigator: Paolo Perona (now at University of Edinburgh)
The efficiency of river restoration actions, like the widening restoration project of the Thur River near Neunforn, relies on river autogenic adjustment which improves ecological health: aquatic habitat for macroinvertebrates and fish, suitable gravel bar habitat for nesting birds, and for natural establishment and succession dynamics of riparian vegetation.
In the RECORD project the Chair developed a framework of field experimental activities for the Thur with which we studied the morphodynamic evolution of the restored reach of the River Thur near Niederneunforn (Switzerland). We focussed on the role of pioneer vegetation roots in stabilizing the alluvial sediment. The use of riparian tree cuttings for river rehabilitation relies on a good understanding of cutting survival and growth responses to environmental variables. A series of experiments aimed at studying the effects of water table fluctuation induced by streamflow variability on the development of below-ground biomass of riparian tree cuttings was performed on the Thur River. White willow (Salix alba) cuttings were installed in gravel bar plots at various locations to show that the transient root growth dynamics create a spatial distribution which reflects the hydrologic conditions (flood inundation and groudwater) experienced towards the end of the growing season. A scaling relationship is presented that is useful to predict the expected depth with the highest root density as a function of soil topography and river discharge statistics.
The results have implications for predicting cutting survival and growth, along with a corresponding strengthening of the alluvial sediment, in different flow regimes. This approach is therefore useful to incorporate in morphodynamic models covering the ecological and hydraulics responses of below-ground biomass to floods.
N. Pasquale, P. Perona, R. Francis, P. Burlando (2012), external page Effects of streamflow variability on the vertical root density distribution of willow cutting experiments, Ecological Engineering, Volume 40, 2012, Pages 167-172, ISSN 0925-8574, https://doi.org/10.1016/j.ecoleng.2011.12.002.
Pasquale, N., Perona, P., Schneider, P., Shrestha, J., Wombacher, A., and Burlando, P. (2011), external page Modern comprehensive approach to monitor the morphodynamic evolution of a restored river corridor, Hydrol. Earth Syst. Sci., 15, 1197–1212, https://doi.org/10.5194/hess-15-1197-2011, 2011.
For further information please visit our project-website (not maintained anymore).
external page REFORM Thur Widening Project