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| Titel |
Measuring, mapping and modeling deep subsurface stormflow contribution to the dampened flood response in a mountainous catchment |
| VerfasserIn |
M. Smoorenburg, N. Volze, P. M. Kienzler, F. Naef |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250068619
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| Zusammenfassung |
| Magnitudes of extreme flood events in steep mountainous catchments show much variation in
terms of peak specific discharge. This can be considered as a variation in dampening of the
flood response and is generally attributed to difference in catchment storage. Particularly in
large mountainous catchments where floods are caused by longer periods with low intensity
precipitation, sometimes thresholds are observed above which the very extreme flood
discharges are much stronger than expected from extreme value statistics on smaller floods.
Therefore, complementary methods for estimation of unprecedentedly large floods are wished
for. For this estimation, it is critical to understand where in the catchment the storages are,
and how much the drainage from these storages could contribute within the timescale of
a flood event. Whereas geomorphological maps may provide good information
about where the areas with large storage potential are, the question of how much the
drainage from these storages could contribute to the flood discharge needs more
research.
The mountainous, 109 km2 Schaechen catchment is a good example of the
aforementioned problems and research was started to investigate the deep subsurface
stormflow contribution of typical geomorphologic formations with large storage potential;
talus slopes, moraines and the thick soils found on creeping landmasses. In order to
understand how fast these areas are drained, discharge measuring stations and rain gauges
have been set up at spring and headwater scales. At the creeping landmass slope, additional
data has been obtained with piezometers in the soil and underlying bedrock, measurements of
natural tracers and sprinkling experiments.
These measurements allowed to identify differences in drainage characteristics and
guided improvements in the mapping procedure of dominant runoff processes as originally
developed by Scherrer and Naef (2003) and Schmocker-Fackel et al., (2007). In the
new mapping scheme, the areas with large storage potential are delineated and it is
tried to classify the deep subsurface drainage processes according to their reaction
time.
In order to evaluate the advantages of the new mapping procedure, the process based
rainfall-runoff model Qarea is supplemented with a new module for drainage of deep
storages. It is tried to infer the structure and parameterization of this module from the
obtained soft data and resort to step-wise calibration on the various observed discharges at
headwater and catchment scale if this is required for parameter identification.
References:
Scherrer, S. and Naef, F.: A decision scheme to indicate dominant flow processes on
temperate grassland, Hydrological Processes, 17, 391-401, 2003.
Schmocker-Fackel, P., Naef, F. and Scherrer, S.: Identifying runoff processes on the plot
and catchment scale, Hydrology and Earth System Sciences, 11(7), 891-906, 2007. |
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