As for the projected population growth, the projections vary. In 2014 Lutz et al. have developed five scenarios for France, and the numbers vary tremendously according to the scenario of development (rapid development, stalled development, medium, inequality, conventional development). To approximately evaluate the possible population trends, an extrapolation from the aforementioned scenarios were made for Plaine Commune (Fig.20).
Fig.20. Scenarios of population changes in Plaine Commune. Source: based on Lutz et al., 2014
Territorial Coherence Scheme (SCOT) of Plaine Commune adopted in 2007 provides for an increase in the population of 50 000 inhabitants by 2020.
All the scenarios predict growth of population till 2050 (between 420 000 and 569 000), after 2050 the growth or decline is less certain. Medium scenario projects around 541 000 people by the end of the 21st century.
Trend of population ageing, especially in the developed countries, is not actually relevant for the population of Plaine Commune and for Seine-Saint-Denis in general, as the major part of their population is young. Yet the number of aged people will considerably grow towards 2040 – from 11% in 2009 to 17,5% in 2040 (Fig. 21)
As for other population characteristics, they remain rather uncertain. There is however, a concern about the increased migration trend on the territory because of projected climate change and its impacts, like resources depletion in other regions or countries.
The built environment of Plaine Commune is going to change during the coming century, too. For the moment, 40% of the territory is undergoing renovation or is studied before launching a renovation project (Plaine Commune 2014). Accordinng to the signed CDT (Contrat de développement territoriale), the objectives are to densify the zones located close to the transport nodes, recycle industrial wasteland, equilibrate the employment and social upgrade in disadvantaged areas, installation of business and innovation centers, pointed improvement where needed. CDT also stipulates the objective of housing construction of 4200 dwellings per year.
Fig. 21 Evolution of the age parameter between 2009 (top) and 2040 (bottom) in Seine-Saint-Denis (right) and Ile-de-France (left). Source: INSEE 2010, Omphale model, medium scenario, as cited in Artelia, RCT, Plaine Commune 2014.