Assessment of Shallow Interflow Velocities in Alpine Catchments for the Improvement of Hydrological Modelling

Advective long-duration rain events play an important role in the development of floods. A realistic depiction of interflow processes is not possible with the most customary precipitation/runoff (P/R) models. To increase knowledge about interflow processes in long-term rainfall events and improve the data situation for hydrological modelling, field experiments were performed in five Austrian catchments. These catchments differ from one another in precipitation characteristics, land cover, land use, pedological and geological situation. Long-term irrigation experiments on large plots combined with the insertion of a salt tracer (LiCl or NaCl) on smaller plots and geoelectrical measurements were used to assess the water movement in the soil and underlying substrate. This study has made significant contributions to (i) improving the design of measuring interflow on the plot and the hillslope-scale, (ii) improving the knowledge of bandwidths of shallow interflow velocities for typical substrates in the Eastern Alps and (iii) facilitating the regionalisation of data acquired at the local level, to the catchment or the regional scale.