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

Brixenbach research catchment: Quantification of runoff process proportions in a small Alpine catchment depending on soil moisture states and precipitation characteristics

“…Large proportions of the water formed overland flow within the first 10 m of the flow section. The infiltrated water showed a subsurface flow velocity of 2.4 m h −1 for the uppermost combined layer of soil and substrate (until 2 m depth) (Markart et al, 2013). Studies on flow velocities in near‐surface subsurface are rare.…”

“…On the third day, salt water was applied at 50 m 2 (2 h 22 min, 17 mm min −1 ). The progress of the seepage front and subsurface flow velocities were observed by geoelectrical profile measurements (Markart et al, 2013). At the opposite slope a salt tracer solution (concentration: 6 mS cm −1 ) was washed into a gleyic soil by use of water from a natural linear irrigation trench along the slope.…”

Hydrogeologische Herkunft und geothermisches Potenzial der Thermalquellen von Hintertux, Österreich

“…Die potenzielle Evapotranspirationsrate beläuft sich für dieses hochalpine Tal-bis Bergklima etwa auf 270-330 mm a -1 (Fecht et al 2009). Das Gebiet mit steilen Hängen und bergauf zunehmend geringer Vegetation und Bodenbedeckung hat ein sehr geringes Wasserrückhaltepotenzial, weshalb der Anteil des Direktabflusses nach Regenfällen 80 % übersteigen kann (Markart et al 2011(Markart et al , 2015.…”

How can we model subsurface stormflow at the catchment scale if we cannot measure it?

“…Rainfall–run‐off models are used for studies that are either investigative or predictive (Blöschl & Sivapalan, ). In both cases, the simulated SSF is mainly calibrated and validated based on single rainfall–run‐off events (e.g., artificial sprinkling experiments) for which tracer hydrological data and information on specific run‐off components are available (e.g., Markart et al, ; Uhlenbrook, Roser, & Tilch, ). However, it is obvious that these single events with steady‐state conditions are not sufficient to capture the whole range of SSF response that depends on factors such as initial conditions and rainfall intensities and is often threshold dependent.…”

“…Intersite comparisons and the extraction of general rules for SSF generation and its controlling factors are still lacking, which hampers the development of appropriate approaches for modelling SSF. But appropriate prediction of SSF is essential due to its clear influence on run‐off generation at the catchment scale (e.g., Chifflard et al, ; Zillgens, Merz, Kirnbauer, & Tilch, ), on the formation of floods (e.g., Markart et al, , ) and on the transport of nutrients or pollutants from the hillslopes into surface water bodies (Zhao, Tang, Zhao, Wang, & Tang, ). However, a precise simulation of SSF in models requires an accurate process understanding including, knowledge about water pathways, residence times, magnitude of water fluxes, or the spatial origin of SSF within a given catchment because such factors determine the transport of subsurface water and solutes to the stream.…”