Abstract
International collaboration between research institutes and universities is a
promising way to reach consensus on hydrological model development. Although
model comparison studies are very valuable for international cooperation,
they do often not lead to very clear new insights regarding the relevance of
the modelled processes. We hypothesise that this is partly caused by model
complexity and the comparison methods used, which focus too much on a good
overall performance instead of focusing on a variety of specific events. In
this study, we use an approach that focuses on the evaluation of specific
events and characteristics. Eight international research groups calibrated
their hourly model on the Ourthe catchment in Belgium and carried out a
validation in time for the Ourthe catchment and a validation in space for
nested and neighbouring catchments. The same protocol was followed for each
model and an ensemble of best-performing parameter sets was selected.
Although the models showed similar performances based on general metrics
(i.e. the Nash–Sutcliffe efficiency), clear differences could be observed for specific events. We analysed the hydrographs of these specific events and
conducted three types of statistical analyses on the entire time series:
cumulative discharges, empirical extreme value distribution of the peak flows
and flow duration curves for low flows. The results illustrate the relevance
of including a very quick flow reservoir preceding the root zone storage to
model peaks during low flows and including a slow reservoir in parallel with
the fast reservoir to model the recession for the studied catchments. This
intercomparison enhanced the understanding of the hydrological functioning of
the catchment, in particular for low flows, and enabled to identify present
knowledge gaps for other parts of the hydrograph. Above all, it helped to
evaluate each model against a set of alternative models.
Citation
ID:
135516
Ref Key:
boer-euser2017hydrologylooking