The semi-arid integrated model (SIM), a regional integrated model assessing water availability, vulnerability of ecosystems and society

Abstract. Northeastern Brazil, an example of vulnerable semi-arid regions on the earth, is characterised by water scarcity and vulnerability of.natural resources, pronounced climatic variability and social stress situations. Integrated studies involving hydrology, ecology, meteorology, climatology, pedology, agronomy, and social and economic sciences are required not only for analysing consequences of the adverse natural conditions but also to assess possible strategies to make semi-arid regions less vulnerable to the present and changing climate. Integrated modelling of the relationships between water availability, quality of life and migration, including aspects of global change processes, in the Semi-arid Integrated Model (SIM) serves to understand the dynamics of the system. An overview of the concept, structure and application results of the integrated model are given. A sensitivity study on climate change illustrates potentially significant adverse effects on the region. Moreover, it shows that a regional integrated model is a suitable tool for complex and interdisciplinary studies. The present version of SIM still is in a development phase, especially in its representation of socio-economi