Expérimentation de la notion de seuil de développement pour l'élaboration d'un outil SMaR²T de planification urbaine locale. .

Abstract

In the Mediterranean region, like elsewhere in the world, the big city is not only largely fragmented, but it consumes also all the rural areas around it. In addition, when going above certain limits, the development reached an urban and environmental crisis. Like many others international and Mediterranean metropolitan territories, the Algiers region is composed of a central urban area and several complementary cities, all of them located on the hills of the Sahel and the plain of the Mitidja. It should be noted, that this plain is environmentally sensitive; it is agricultural and it provides a real foodshed for its inhabitants. During the last 30 years, these small and medium towns played an important role in absorbing the urban growth excess in this region. In fact; when these towns are the place of massive and rapid urban development, they disturb at the same time food security and sustainable development of Algiers. This research has put forwards two hypotheses: - When the Metropolitan areas become the preferred place of urban growth, the exceeding limits and thresholds for their growth could not only jeopardize the implementation of a sustainable development approach at the local level, but could also cause irreversible impacts quality of life in urban areas. - We assume that the creation of a specific spatial planning tool to the area identified as sensitive, particularly that of Algiers Mitidja and its complementary cities, studied and based on the observation of urban development thresholds of these towns, can help in the development of sustainable development strategies of the territory of Mitidja that would balance urban sustainable development of the metropolitan area of Algiers. It should be noted, for the second hypothesis, that the development of the tool is not a comprehensive strategy and will require future additional experiments. However, the negative impacts of development must be central to our concerns. These depend on a matrix of triggers and amplifiers and on their acceptability thresholds. The thresholds in turn depend on carrying capacities of social-ecological system; they are interrelated either to resources: natural, human, biological, economic or to other components: socio-functional, morphological and territorial managerial. The threshold can take the form of a maximum or minimum acceptable value, as a point of no return, beyond which, the system would suffer irreversible damage. This research promotes the concept of thresholds for urban development planning tool, it then uses several types of theoretical and conceptual fields: strategic urban planning, urban design, management, urban intelligence, urban resilience, etc. During the experimental phase, an observation tool was developed and completed. This was simulated taking as a case study the municipality and agglomeration of Eucalyptus in Algiers Mitidja. This tool is a threshold index tool, by a point indicator scale; this research called it a “SMaR²T-acceptable Thresholds index”.