Deterministic hydrological models for extreme floods

The role of deterministic models in SPATE is twofold: (a) Models are used to formalize knowledge, resulting e.g. from event analyses; (b) Models are used to simulate rare extreme events, and to explore the interactions between processes and the sensitivity to modified drivers and boundary conditions.
Since one research question of the Research Unit is the ability of deterministic models to explain extreme events, this task force will integrate the findings of several SPs with regards to extremes. The aim is not to develop a common model but to compare several models with regards to optimal descriptions of nonlinearities and thresholds in the response of watersheds to heavy rainfall. As the subprojects have different perspectives on extreme events, also their modelling approaches differ. The models range from mHM, SALTO, Larsim and HBV to newly developed model chains to consider single processes (e.g. flood routing) in a modular way and to test the opportunities to simulate a wide range of possible flood events. While SP1, 4 and 7 focus on testing deterministic models concerning their ability to perform well for all event types, SP3 will use a model chain that includes the entire flood process cascade from triggering meteorological events to river routing, e.g. to consider dyke failures. Regarding role (b), deterministic models will be used to explore the relevance of different factors that contribute to the maximization of floods. SP1 will investigate how the interchange of triggering components affects the extreme floods, while SP5 will concentrate on the simultaneous occurrence of extremes by including phase randomisation and simultaneous calibration. Finally, SP7 will deliver insights on the need for non-stationary parameters. The hydrological models will simulate all events types and the whole spectrum of magnitudes of floods in space and time. To ensure their accuracy, the task force will evaluate the advantages and disadvantages of the individual models and give recommendations on the optimal combination of deterministic models and weather generators. In addition, the ability of models to simulate extreme floods will be evaluated to specify the need for further developments in this sector.

The head of the task force will be S. Vorogushyn (SP3), members are: A. Schumann (SP1), R. Merz (SP4), A. Bardossy (SP5) and U. Haberlandt (SP7).