Land-use modelling to support strategic urban planning - the case of Dar es Salaam, Tanzania

At the beginning of the 21st century humanity entered the 'century of cities' (Kofi Annan) with the majority of the global population living in urban areas. Global urbanisation is one of the most fundamental and most radical changes recently experienced by humanity. In the last decades new so-called megacities highlight that " the developing world, where megacities will be the hallmark of future urbanisation, is experiencing extraordinary spurts of growth in its largest cities " (UN 2007). Urban growth in an informal environment is neither guided by strategic planning nor zoning specifications. " Urban planners and managers have increasingly found themselves confronted by new spatial forms and processes, the drivers of which often lie outside the control of local government " (UN-Habitat 2009: xxiii). Informal urban settlements are characterised by severe deficits in basic services and infrastructure supply calling for strategic urban planning and action taken to qualify informal settlements to meet the Millennium Development Goals (MDG) of the UN and to contribute to a sustainable urban development. This contribution focuses on informal urban growth processes in Dar es Salaam, one of the most rapidly growing large cities in Africa. Although research has focused on informal urbanisation and many studies on megacities were conducted in the past years, knowledge about the drivers and mechanisms influencing informal urban dynamics is still incomplete. As a step towards a better understanding of the underlying processes this paper presents selected findings from research to explore, model and simulate informal urban growth processes using the modelling approach of cellular automata (CA) (Hill & Lindner 2010a, 2010b). CA models seek to reproduce development patterns and the underlying mechanisms on an aggregate cell-based level. Based on the knowledge generated, they can be used to identify suitable access points for planning intervention, to forecast likely future trends and to demonstrate the impacts to be expected from selected planning measures. Eventually the modelling exercise can contribute to a more strategic planning approach and sustainable development. A particular focus of this contribution is to demonstrate the potential of transport infrastructure as an access point for planning intervention to guide future informal development.