Summary Report No. 82

Simulation der Siedlungsflächenentwicklung als Teil des Globalen Wandels und ihr Einfluß auf den Wasserhaushalt im Großraum Berlin

B. Ströbl, V. Wenzel, B. Pfützner (April 2003)

Possible impacts of Global Change on the regional water balance is one of the aspects studied in the project GLOWA-Elbe, funded by the German Federal Ministry of Education and Research.
This study focusses on the corresponding peculiarities of Greater Berlin as an example of an urban agglomeration. Especially regions of this kind are affected by the process of urban sprawl accompanied with accelerated consumption of land and sealing, processes that are very crucial for the rain-water runoff in the region.
Thus, the most relevant Global Change phenomena to be considered in this respect are changes in climate and therewith in precipitation and evaporation on the one side and the dynamics of socioeconomic driving parameters for the mentioned urban sprawl process on the other side. This process can be observed and must be considered even in a country like Germany with a more or less stable population.
The study identifies and analysizes three different regional trends of urban development, each following a certain guideline assumption. The trends are quantified and spatially allocated. For this purpose a landuse simulation tool was created and implemented into a commercial GIS package. It is described here in detail and includes a two-step procedure: In the first step rules are defined stating each locations’s suitability for a land use change to take place. Next a stochastic process allocates the desired amount of change within the area of highest suitability.
A digital landuse map for the region was compiled from different sources with special attention to the grade of sealing and type of sewer system for urban areas. It is merged with the urban development simulation results to serve as input for the hydrological modelling system ArcEGMO. First modelling results show that the impact of urbanisation on the mean runoff is minor compared to the impact of the assumed climatic changes. However, one catchment mainly affected by the urbanisation process shows considerable changes in peak runoff figures compared to the status quo landuse.


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