The research method applied to the landscape of the south-eastern sector of the city of Cagliari required a first phase aimed at a historical-geographical introduction of the area and at the definition of some synthetic analysis on an urban and territorial scale.
These path of knowledge wants to highlight the territorial determinants that led to a current configuration defined by a sequence of natural elements of extraordinary landscape value such as the hills situated at the mouth of the great
Cagliari landscape context. The graphic synthesis shows the anthropic pressure determined by the urban growth on wet areas
The beach, the wetlands and the salt works are, together with the hills, the most valuable elements of the landscape in the Cagliari area, the result of water management works carried out initially with only human work, later with the use of animals and finally with mechanical tools.
These elements constituted the authentic “settlement principle” of the area where the lagoons, in particular, were sources of decisive resources: in addition to fishing, the landing place (especially the western ponds) and the extraction of salt (mainly from the
Based on these fundamental “environmental vocations” the human settlement of the sites will be organized according to a distinction that was established since the stage of Romanization of the territory: west – port facilities and strictly urban destinations, east – settlement structure centered around the pond of
In its current configuration, scaled down compared to the nineteenth-century dimension, the wetlands is included within the
The study area preserves the signs of an ancient frequentation and a continuous use mainly linked to the control of the landing places and to the exploitation of the resources of the salt works.
This use has determined the maintenance of a system of paths on which urban growth has been grafted – linked to the presence of military and industrial structures – that we can know in depth through the comparison between the nineteenth-century maps and the most recent aerial surveys.
The nineteenth-century representations in particular describe the “modern” project of the Piedmontese salt works [1] in a landscape context characterized by a strong natural component and the presence of the infrastructural network that will guide the development of the city towards the coastline.
The historical maps selected for the present study are characterized by a scientific rigor that foresees the widespread use of the graphic codes shared in the European area starting from the early nineteenth century but also for the strong communication skills offered by the wise use of colors and shapes that show the wetlands and the persistence of cultivated fields, the latter destined in the second half of the nineteenth century to completely disappear.
The cartographic database thus constituted is characterized by a remarkable detail and care in the representation of the elements of the landscape and a quality of the data that allows an easy graphic overlay with the most recent cartographic productions; this condition allows a diachronic analysis of the transformations and through the decomposition and recomposition of the interpreted signs, the definition of some graphic models that highlight expansions and contractions of the different landscape units.
In this phase, the re-drawing of the archival document assumes considerable importance as a tool capable of leading with the right timing an investigation path aimed at communicating single or integrated aspects that contribute to the global design of a landscape always in a dynamic balance, in continuous movement; accepting the operational lines of structuralist current and with the aim of defining an operational methodology, therefore we decompose the landscape into its constituent parts in order to classify them and then reassemble it in order to understand the relationships that join the individual parts and each of them to all [2]. To this end the graphic information is structured to lead to a reasoned redrawing, the result of graphic choices obtained with the omission and/or sometimes the emphasis of some signs and with the use in the digitalization of different graphic primitives – in function of a suitable representation of the sign with purely “artificial” (lines, polylines) or “natural” (splines) – and thicknesses and line types – in relation to the “landscape” weight of the objects represented.
The first document examined is the map of Captain W.H. Smith who, as it is well known, will contribute to the compilation of the Map of the Kingdom of Sardinia – published in 1845 by General Alberto Ferrero Della Marmora – with the data relating to the soundings represented by three different types of lines (according to the increasing depth) and carried out along the coasts of the entire island.
The map, engraved by J. & C. Walker, entitled “Sardinia Cagliari Bay”, in scale 1: 27.000 oriented and with metric scale, is dated 1823, accurately describes the stronghold and its suburbs (with a perfect correspondence with the coeval map of Luigi Ferrero Ponsiglione, a military officer) and the physical and anthropic components of the landscape of a large portion of the Gulf of Cagliari; the coastal towers are correctly identified (although in some cases with a wrong name such as the
Detail of Captain Smith’s map (Accardo-Fontana private collection, Museo Casa Manno, Alghero-Sardinia). The graphic elaboration shows the relationship between the territorial determinants (system of hills and wetlands) and the historical settlement
The document is very interesting because it precedes the works aimed to improve the salt works undertaken in the 1930s and because it accurately transmits the signs of a landscape that today we can only partially observe. The shapes of the territory are described with rigor where the orography is represented with the typical “oblique light line” suggested by the Mémorial prepared in 1803 by the French commission which, following the examination limited series of cartographic productions chosen as representative examples of the state of the art in Europe, declares itself in the “merit of the purposes and uses of the cards, discuss their contents, provide indications on the construction procedures ... and on the training of the men called to perform the topograph ic operations” [3]. This description is supplemented by some elevation data and toponyms linked to the history of the places (for example
View of 1832 in which the following are represented: 1 – Management building of Salt works, 2 – Building, 3 – new
“Piano di tutte le saline erette, e da erigersi nel circondario di Cagliari” that describe the plan of all the erected salt works and to be erected in the district of Cagliari (19th century document kept in ASCA, the State Archive of Cagliari)
The second map analyzed (Fig. 5) is called “Plan des salines royal de Cagliari” and was realized in the middle of nineteenth-century; the map is compatible – like the map of 1823 – with aerial images provided by the Cartographic Service of the Sardinia Region. Analyzing the images of 1940–45 we clearly observe the drawing of the nineteenth-century salt works of Lazzaretto (which overlooks the bay represented in the nineteenth-century view in Fig. 6) and of the canal that runs along it (Fig. 7) completely lost in the 1970s with the construction of the new Sant'Elia district and the implementation of a new road system. The drawing, in addition to showing the successful realization of the ordered system of the canals that connect the salt system with the ponds and the sea, identifies a series of new architectures including the penitentiary (1842) and the first nineteenth-century buildings, the warehouse system and the salt dock. The route system here represented appears to be rationalized and rectified; it no longer leads to cultivated land and shows some axes that will become important for urban development, including the current
Original document (kept in ASCC, the historical archive of the municipality of Cagliari) and graphic elaboration of the nineteenth-century map aimed at showing the strong landscape design of wetlands
Penitentiary (n.32) and new Lazzaretto (n.34) in the drawing realized by the piedmontese military officer Carlo De Candia and published in Della Marmora 1860. On the right of the drawing we can recognize the wide bay that delimited the ancient salt works of the
Graphic correspondence between the nineteenth-century map and the aerial photo dated 1940–45; the comparison shows the modification of the coastline and the permanence of
In the search for define an image of a territory we can aim at the representation of the appearance that characterizes it or at the representation of the phenomena that lie behind it [5].
The cartographic analysis on an aerial basis returns an image conceived as a two-dimensional idea [6], highlights the organization of the urban fabric and allows a diachronic reading of the transformations of a precise territorial context. Its representation can take place through graphic models that, although deriving from the forms acquired through digital survey methods, are characterized by a perceptive component and linked to the phenomena that led to the current territorial structure [7]. The possibility of graphic overlay among the selected documents offers the opportunity of a careful study of the transformations of the historical landscape and the identification of the traces of the disappeared assets. Through the use of traditional and digital tools the precise data offered by recent information technologies becomes the means capable of communicating even the most complex analyzes to a vast public.
The aerial images employed show since the 40s of the twentieth century the advancement of the coastline and the occupation of the bay between the exit of the canal of the
The analysis of the documents also makes it possible to identify the position of the old
The historical city and the study area seen from Calamosca hill (drawing by P. Solla, scientific coordinator A. Pirinu)
The syntesis shows the urban growth that occupies the salt works of the
Relationship between landscape components and territorial dynamics in the study area (on the left); the landscape context of Cagliari represented on an aerophotogrammetrical survey dated 1998 integrated with the use of aerial images of 2008 (on the right)