| Decision support for planning and management of water resources needs to
consider many target criteria simultaneously like water availability, water
quality, flood protection, agriculture, ecology, etc. Hydrologic models
provide information about the water balance components and are fundamental
for the simulation of ecological processes. Objective of this contribution is
to discuss the suitability of classical hydrologic models on one hand and of
complex eco-hydrologic models on the other hand to be used as part of
decision support systems. The discussion is based on results from two model
comparison studies. It becomes clear that none of the hydrologic models
tested fulfils all requirements in an optimal sense. Regarding the simulation
of water quality parameters like nitrogen leaching a high uncertainty needs
to be considered. Recommended for decision support is a hybrid metamodel
approach, which comprises a hydrologic model, empirical relationships for the
less dynamic processes and makes use of simulation results from complex
eco-hydrologic models through second-order modelling at a generalized level. |