The water balance of many wetlands in the North-East German Lowland is dominated by water resources management systems with drainage and subirrigation. These systems are integrated in the water resources management system of their whole river basin. Scenario investigations show the possibilities and constraints of different water resources management options within the wetland and in the basin. For the Spreewald wetland strategies for the mitigation of negative impacts of climate change are presented as an example.

This paper presents the development of a wetland water balance model for use in a large river basin with many different wetlands. The basic model was primarily developed for a single wetland with a complex water management system involving large amounts of specialized input data and water management details. The aim was to simplify the model structure and to use only commonly available data as input for the model, with the least possible loss of accuracy. Results from different variants of the model and data adaptation were tested against results from a detailed model. This shows that using commonly available data and unifying and simplifying the input data is tolerable up to a certain level. The simplification of the model has greater effects on the evaluated water balance components than the data adaptation. Because this simplification was necessary for large-scale use, we suggest that, for reasons of comparability, simpler models should always be applied with uniform data bases for large regions, though these should only be moderately simplified. Further, we recommend using these simplified models only for large-scale comparisons and using more specific, detailed models for investigations on smaller scales.