01 Dinamiche urbane e città post-socialiste: monitoraggio mediante telerilevamento. Casi di studio

In the last three decades many economic and politic changes involved post-socialist Countries. Their impacts have big effects on the most important parameters like, for instance, Gross Domestic Production (GDP) or Per capita Income, but also on the social and cultural issues, leading migrations between rural and urban areas. In order to examine main changes occurred in four towns (Sibiu in Romania, Pripyat in Ukraina, Astana in Kazakhstan and Shanghai in China), we considered satellite images (Landsat TM/ETM+/OLI or Terra MODIS/ASTER) in the timeframe from ’80 till today. Using visual interpretation or NDVI (Normalized Difference Vegetation Index) vegetation index and overlaying the free digital cartography of OpenStreetMap Project on satellite images, we evaluated urban dynamics for these post-socialist towns. Sibiu is a medium city located in a charming region at the centre of Europe, the Transylvania. By the comparison between the master plan realized in the 1974 and a recent ASTER satellite image (2003), we realized how the urban growth is following - until now - the socialist guidelines. However, in this timeframe the historic town centre is maintaining its identity role, unlike the planning developments: European cultural capital in 2007, Sibiu well represents the ‘inherited’ town. Otherwise, Pripyat is an almost unknown city of Ukraine: it was built since 1970 to serve the nearby nuclear power plant of Chernobyl. But from 1986, when the nuclear catastrophe occurred, this little town (about 45.000 people lived here) has become the symbol of the social and environmental risks linked to this technology. As put in evidence also from the overall NDVI increase estimated by the comparison of the 1986 and 2014 Landsat TM/OLI images, Pripyat is now a ‘ghost city’ for a region where the social, economic and environmental impacts of this disaster are still very relevant. Sited in a region characterized by extreme climatic conditions, the new capital of the Kazakhstan - Astana - is the third case study. The Landsat time-series images (collected between 1985 and 2016) shows its fast growth, mostly in the last period after the 1997 (year in which it became capital), so nowadays there are more than 830.000 people. Satellite images put in evidence main transformations inside the old city: new religious places, new halls of the power and new quarters are inserted in the original socialist urban network, currently changing this town in a ‘postmodern’ city. Finally we considered the most populous town of the China, Shanghai. In the last decades its demographic growth is impressive, rising from 12 million people in the early 1980s to the current almost 25 million people. So, also from the spatial perspective, the urban dynamic of Shanghai is remarkable. Visual interpretation of satellite images (four Landsat images from 1985 till 2016) highlights the deeply changes of the Shanghai municipality (about 6.450 square Kilometers), from rural into urban. Besides, the comparison between vegetation indices (evaluated on the Landsat images) put in evidence a new reticular urban network involving also the neighbouring regions. The free availability of software GIS (Geographic Information System) open source and data (digital cartography and satellite images) gave us the chance to achieve interesting results about four very different urban areas. However, these towns had a common history for a brief period of their ‘life’, so in the recent past their master plans and their urban development had deeply influenced by socialist criteria. Using these four examples, this research is only the first step trying to answer to the following question: almost thirty years after the fall of the Berlin Wall, what are the post-socialist evidences left in these cities?