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This study examined the hydrodynamic behaviour of European black poplar (Populus nigra L.) under coppice management in riparian areas with a multidisciplinary approach. An innovative procedure on the basis of the combination of plant allometric relations and hydrodynamic models was applied to assess drag forces and plant hydrodynamic bending as function of the basal diameter and module of elasticity, with a probabilistic approach. Cuttings of European black poplar from 2 close riverine environments of Southern Italy have been planted and subjected to the same coppice management strategy. The 2 different 3‐year‐old shoot poplar ensembles exhibited statistically similar morphological traits but stems with different module of elasticity. Drag forces were simulated with a model on the basis of the vegetative Cauchy number. Plant deformation under the hydrodynamic load was modelled as a basemounted cantilever beam. The differences in the observed elasticity were verified to be also significant from a hydrodynamic perspective. Diagrams were drawn to describe plant bending, drag forces, and basal momentum as function of basal diameter, accounting for the uncertainty in the module of elasticity. These results can be exploited for identifying objective hydrodynamic criteria to be adopted for coppice management of riparian woody vegetation in human controlled river ecosystems.

The thawing of alpine permafrost in a warmer climate may alter the runoff regime of high alpine catchments. We present a case study where detailed geophysical and geological field investigations were performed in a 5 km2 large catchment in Western Austria to assess its main hydrogeological settings. Ground-penetrating radar data, seismic refraction measurements and ground-surface-temperature data were employed to map the spatial permafrost distribution and depth of the permafrost table and the bedrock interface. The results for different types of unconsolidated sediments were then translated into five sets of flow path concepts in the presence and absence of permafrost. These concepts were then used to set up a rainfall-runoff model and simulate the runoff response of the catchment for scenarios with and without permafrost. The simulations indicate that the complete thawing of permafrost will increase the catchment storage capacity which will reduce the flood peaks by up to 20% and increase runoff during recession by about 15%. The reduction of extreme events is important since it may also affect flood events in downstream catchments. The study highlights the importance of interdisciplinary work between hydrology, geophysics and geology which can greatly help to improve the understanding of subsurface processes.

Alpine permafrost is prone to decrease in a warmer climate as a consequence of climate change which in turn may affect the runoff regime of high alpine catchments. In the presented case study detailed geophysical field investigations were performed in a 5 km2 large catchment in Western Austria to gain information about subsurface properties and permafrost occurrence. Ground penetrating radar, seismic refraction and ground-surface-temperature measurements were applied to map the spatial permafrost distribution, depths to the permafrost table and bedrock interface. This information was used to infer subsurface flow paths concepts for different geologic formations in the presence and absence of permafrost. The concepts were then used to set up a rainfall-runoff model and simulate the runoff response of the catchment for scenarios with and without permafrost. The results of the study show that geophysical information helps to improve the understanding of subsurface processes and to reduce the parameter identifiability problem. Subsurface model parameters are well constrained by the available field information and require little calibration. Furthermore, the simulations indicate that the melting of permafrost increases the available catchment storage which causes a reduction of flood peaks and an increase of runoff during recession. A reduction of extreme events is important since it may also affect flood events in downstream catchments.