Geography Reference
In-Depth Information
Figure 3.15. Early winter snow cover and frozen streams lead to low baseflow and increasing amounts of water stored in the snowpack for
spring melt. High flow conditions driven by enhanced landscape hydrological connectivity and variable source area dynamics. Decreasing
baseflow through summer growing season and transition to autumn. Photos: F. Nippgen and C. Kelleher.
process will remain uncertain without additional data col-
lection and interpretation. Attributing specific runoff
dynamics to catchment form and runoff processes can
require multiple years of intensive field observations, but
can yield insight into those aspects of catchments that can
be used to constrain PUB elsewhere.
3.7.2 Runoff predictions using rainfall
runoff models
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(Chicken Creek, Germany)
A PUB comparison study using 12 hydrological models
was performed at the artificial Chicken Creek catchment in
Germany in the context of the Transregio-SFB 38 research
project (Holländer et al., 2009 ; Bormann et al., 2011a ,
2011b ). The modellers were tasked with modelling the
catchment with varying degrees of information available
to them. The catchment has a size of 6 ha (450 m × 130 m)
and was created in 2005 (Gerwin et al., 2009 ; Figures 3.16
and 3.17 ). It is bounded at the bottom through a 2 m clay
layer, which is covered by 2
Figure 3.16. Photo of the artificial Chicken Creek catchment near
Cottbus, Germany. Photo: BTU Cottbus FZLB, 2007.
deeper groundwater sources of runoff with little active
upland hydrology except for zero-order basins and areas
of greater upslope accumulation as evidenced by exfiltra-
tion and the hillslope
3 m of (mainly) sand. A lake
has formed in a depression that was implemented close to
the catchment outlet. Regional annual average temperature
is 9.3 C (1971
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riparian topographic transition. Field
reconnaissance during more hydrologically active times
(e.g., spring snowmelt or rainstorms) reveals subsurface
stormflow (throughflow) dominated hydrology with vari-
able source area saturated overland flow. Variable land-
scape contributions to runoff generation are evident in
saturation extending from riparian zones into convergent
hillslopes of greater area accumulation. Little to no infil-
tration excess overland flow is observable save in areas of
exposed bedrock and forest roads.
Despite this, the strength of inference that can be drawn
from the data hierarchy, quantification of the specific mag-
nitude and timing of catchment runoff dynamics, and the
relative magnitudes and spatial distributions of runoff
-
-
2000) and annual precipitation varies
between 335 mm/yr and 865 mm/yr. No vegetation was
artificially added to the catchment.
'
Artificial catchments are per se the opposite of
ungauged catchments because they are supposed to pro-
vide a well-documented case (e.g. a clear definition of
catchment geometry and boundary conditions)
(Holländer
et al., 2009 ). However, in this study it was assumed to be
ungauged in the sense that most of the available infor-
mation on catchment characteristics was withheld by the
organisers of the model
'
inter-comparison study. Time
series of hydrological
fluxes (e.g.,
runoff) and state
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