Zusammenfassung
Abstract. A blended model structure has emerged as an
alternative to the traditional representation of model structure
in a hydrologic model, in which multiple algorithmic choices are
used to represent some hydrologic process within a model, and
are combined within a single model run using a weighted average
of process fluxes. This approach has been shown to improve
overall model performance, as well as provide an efficient way
to test multiple model structures. We propose that a blended
model may also be at least a partial solution to the calls for a
more robust Community Hydrologic Model, which can mitigate the
need for developing new hydrologic models for each catchment and
application. We develop an updated version of the blended model
configuration which defines the suite of all possible hydrologic
process options in the blended model. Configuration development
was guided by model performance for more than 30 different
discrete model configurations across 12 MOPEX catchments.
Improvements to the blended model include the introduction of
blended potential melt and potential evapotranspiration as new
process groups, inclusion of non-blended structural changes, and
a revision of the process options within each existing group.
This leads to a very high-performing model with a mean
calibration Kling-Gupta Efficiency (KGE) score of 0.90 and mean
validation KGE score of 0.80 across all 12 MOPEX catchments, a
substantial improvement in model performance relative to the
initial version of 0.06 and 0.07 in calibration and validation,
respectively. We test for overfitting of models and find little
statistical evidence that increasing the complexity of blended
models reduces validation performance. We then select the
preferred model configuration as version 2 of the blended model,
and test it with 12 independent catchments, which shows a mean
calibration and validation score of 0.89 and 0.76, respectively,
and improvement over the original model (0.03 in mean
calibration KGE score). Version 2 of the blended model is robust
across a range of catchments without the need for adjusting its
flexible model structure, and may be useful in future hydrology
studies and applications alike.
Nutzer