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| Titel |
The Wageningen Lowland Runoff Simulator (WALRUS): development of a novel parametric rainfall-runoff model using field experience |
| VerfasserIn |
Claudia Brauer, Paul Torfs, Ryan Teuling, Remko Uijlenhoet |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250086830
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| Publikation (Nr.) |
 EGU/EGU2014-763.pdf |
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| Zusammenfassung |
| We present the Wageningen Lowland Runoff Simulator (WALRUS), a novel rainfall-runoff
model to fill the gap between complex, spatially distributed models for lowland catchments
and simple, parametric models for mountainous catchments. From observations and
experience from two Dutch field sites (the Hupsel Brook catchment and the Cabauw polder),
we identified key processes for runoff generation in lowland catchments and important
feedbacks between components in the hydrological system. We used this knowledge to design
a parametric model which can be used all over the world in both freely draining lowland
catchments and polders with controlled water levels.
While using only four parameters which require calibration, WALRUS explicitly
accounts for processes that are important in lowland areas:
(1) Groundwater-unsaturated zone coupling: WALRUS contains one soil reservoir, which
is divided effectively by the (dynamic) groundwater table into a groundwater zone and a
vadose zone. The condition of this soil reservoir is described by two strongly dependent
variables: the groundwater depth and the storage deficit (the effective thickness of empty
pores). This implementation enables capillary rise when the top soil has dried through
evapotranspiration.
(2) Wetness-dependent flowroutes: The storage deficit determines the division of rain
water between the soil reservoir (slow routes: infiltration, percolation and groundwater
flow) and a quickflow reservoir (quick routes: drainpipe, macropore and overland
flow).
(3) Groundwater-surface water feedbacks: Surface water forms an explicit part of the
model structure. Drainage depends on the difference between surface water level and
groundwater level (rather than groundwater level alone), allowing for feedbacks and
infiltration of surface water into the soil.
(4) Seepage and surface water supply: Groundwater seepage and surface water supply or
extraction (pumping) are added to or subtracted from the soil or surface water reservoir.
These external fluxes affect the whole system through the groundwater-surface water
feedbacks and saturated-unsaturated zone coupling.
Model verification with artificial examples shows that the implemented feedbacks have
the desired effect on the system variables, and validation studies with data from the
Hupsel Brook catchment and Cabauw polder yield good results, both in terms of
Nash-Sutcliffe efficiency and according to field experience of processes between rainfall and
runoff. |
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