Maps are drawn thanks to the data collected during the first year of field work. But the previous cartographic systems were complex –especially the one established during the French colonial period- and are not really usable by modern technology.
We have thus to catalogue all collections of photographic archives in order to produce usable maps.
Collecting maps
The search for old maps of the two Vietnamese provinces of Thừa Thiên – Huế and Quảng Trị initially focused on archives available in France. For this purpose, the project plans to search through the archives of the National Geographic Institute (near Paris), the National Archives of Overseas Territories (Aix-en-Provence), the National Defence Archives (Vincennes) and the French National Library (Paris).
We currently have at our disposal a corpus of maps covering the French colonial period, that is to say, from 1875 to 1953. These maps were produced by the National Geographical Service using accurate field surveys. We currently have regional maps dated 1875, 1877, 1880, 1883, 1886, 1889, 1893, 1897, 1899, 1901, 1908, 1923, 1925, 1929, 1940, and a set of aerial photographs taken in 1952-53. The large-scale maps (larger than 1: 500,000) could not be included in this study because they do not provide a sufficient level of details.
For each potentially interesting map, we need a .tiff image, which is cut out (by a computer graphics designer in the PACHA project). Then, with the ArcGis software (ESRI France licence), we georeference each map. It is a long and complcated process to validate each « hanging » point (or daymark). Then, all georeferenced maps are gathered together. And finally, each general map has to be vectorised (i.e. digitised in the Pseudomercator reference system). So, each vectorised map can be superimposed on the others, as soon as the geographic coordinates of each archaeological point has been turned into the same projection of Bonne.
Being mainly focused on the two regions of Thừa Thiên – Huế and Quảng Trị, the documents are of a considerable historical interest, because this area was the craddle of the first Chams, and became the craddle of the Nguyễn dynasty. By precisely representing archeaological sites and historical locations on carefully spatialized documents allows a better understanding of the regional spatial dynamics for the first time. It also enables a better comprehension of the impacts of temporality in the spatial data modelling.
Our search for document was organised along two main categories: the first category has gathered texts and maps written in a Western language, and the second category is composed of the documents written in Hán-Nôm or Chinese.
Western maps
In the Overseas Archives at Aix-en-Provence, we were able to peruse papers, as well as maps and plans. We have bought 42digitalised documents, from the French colonial period, between 1876 and 1952.
These documents are being georeferenced.
At the National Institut of Geography (IGN), a large number of graphic documents have been selected, and Ordnance Survey maps (scales : 1 :100,000 and 1 :25,000) have also been purchased. It takes much time to wedge the maps, because each map must be processed before being gathered with the other mapos. The final digital images remain very heavy.
Asian maps
The analysis of the Chinese and Sino-Vietnamese maps led to the conclusion that it is extremely difficult to use them, because these maps are not geographic, but military and political documents. They represent social spaces without any actual anchoring in the topography. Moreover, they are designed on a large scale, which renders study at a local level somewhat arduous. Yet, some of them are presently collected, such as, for instance, the 1477’ Portulan ou the Descriptive Greography of Đồng Khánh emperor, that dates back to the end of the 19th century (Ngô Đức Thọ, Nguyễn Vǎn Nguyên, Philippe Papin (2003), Đồng Khánh địa dư chí = Géographie descriptive de l’empereur Đồng Khánh = The descriptive geography of the Emperor Đồng Khánh , Hà Nội : Thế giới)..
The Chinese or Chinese-Vietnamese maps are, for the most part, unpublished and it is difficult, or even impossible, to have access to them in the local archives in Vietnam. A bibliographic research indicated the existence of local maps dated from 1490 up until the present day. However, it seems that these old maps cannot be georeferenced, because they are more political (or military) than geographic; And above all, much of the information contained in those maps was written directly on them and this is essential to have a thorough understanding of these documents. The geographic sketches cannot therefore be dissociated from the comments and explanations written on them; on these maps many writings in Sino-Vietnamese (or Hán-Nôm) are to found, which accounts for the sketche used as visual support.
Thus, Asian maps must be deciphered before one can use them, because the written data are absolutely necessary for any studying on landscape’s resilience. This deciphering stage is currently being carried out.
Thus, a comparative examination of the cartographic documentation, both Western and Asian, shows that a multidisciplinary approach is necessary because the different maps can be studied in a complementary and fruitful manner. They provide additional elements of analysis in the context of a study of the processes of formation, evolution, and decline of the Tam Giang-Cau Hai Lagoon.
The insights provided by the written documents are undeniably useful in the study of the resilience of the landscape. The documents written in Western and Vietnamese languages, including the annals in Chinese-Vietnamese (Hán Nôm), are studied in the framework of the PACHA project.
Aerial images
