A system dynamics approach to African urban problems: A case study from the Sudan

Africa is recording a rapid rate of urban growth as a result of both massive rural-urban migration and high rates of natural increase. The major portion of this growth is taking place in the largest cities, particularly the capitals, where development tends to be polarized. Usually, the cities are not prepared to absorb this growth. The discrepancy generates many spatial and social problems, including: high unemployment rates with employment in the informal sector; inadequate housing sectors with higher population densities; declining social gradients with distance from the centers resulting in the concentration of the poor at the peripheries of the cities; and built-up areas that are growing rapidly and are characterized by deteriorating social and public services.; Following the system dynamics approach and emphasizing the close interrelationships between urban problems this study develops a dynamic framework for examining and monitoring the growth processes which generate them. The framework envisages the character of an African city to be determined primarily by the interaction of five components: the population, employment, housing, services, and land sectors. This interaction is structured through DYNAMO causal maps, flow diagrams, and difference equations. Applying an iterative process the hypothesized structure is programed into a continous computer simulation model. The model parameters are based on a field-collected data about a laboratory city, Greater Khartoum, the capital of the Sudan, for the period 1956-1986. A Chi Square test is used to help establish relevancy of the simulation results to the historical data (validity). The model is then used to simulate the projected growth of the city up-to the year 2006 and test the impact of three intervention policy scenarios to control its growth and alleviate the problems. The spatial manifestations of these policies are evaluated and their long term influence on Greater Khartoum assessed.; The study emphasizes the relevancy of a systemic, comprehensive, and dynamic approach to the evaluation of the instrumental urban processes. It concludes that rural development is central to dealing with the impending urban problems of Africa and that more spatially oriented strategy is needed in planning the social and economic organization of the national spaces of the African countries.