Integration of multi-scale dynamic spatial models of socio-economic and physical processes for river basin management

Planners, policy-makers and their technicians have the difficult task to intervene in complex human-natural systems. It is not enough for them to focus on individual processes; rather it is necessary to address the system as a complex integral whole. In the given circumstances, integrated models as part of Policy Support Systems (PSS) can provide support. The MedAction PSS incorporates socio-economic and physical processes in a strongly coupled manner. It is implemented with the GEONAMICA application framework and is intended to support planning and policy making in the fields of land degradation, desertification, water management and sustainable farming. The objective of this paper is to provide some insight in the individual models, the model integration achieved, as well as the actual use of the MedAction PSS. For the latter an application example is developed. The paper also argues that technical and scientific aspects of Policy Support Systems are not the sole elements deciding on their use in practice and concludes with some lessons learned during the development and use of the MedAction PSS and similar systems.