Monday, July 14, 2008

Mapping Greek Landscapes in GIS

Like most archaeologists who deal with Greek field surveys, I've struggled with problems of digital maps and databases. Geographic Information Systems (GIS) require a level of standardization that is difficult to get from Greece. Part of the problem is that, unlike the U.S., most of the cartographic data is not already digitally available but must be constructed by the project. Usually, we have to digitize paper maps, which are difficult to procure on their own right. The most reliable maps are 1:50,000 sheets produced by HAGS/ΓΥΣ (Hellenic Army Geographical Service/Γεωγραφική Υπηρεσία Στρατού), which is the equivalent of the Core of Engineers. One can get these maps in the Army Geographical Service offices at Pedion tou Areos, Athens. In addition, 1:5,0o0 maps are also available here, as well as aerial photography. However, it is illegal to take them out of the country (although most people do). But that's only part of the problem. Some sheets are not available at all because of sensitive areas. For example, I have been trying to get coverage for Prodromos Monastery near Serres (see, Mount Menoikeion Seminar). Thanks to the site's proximity to the Bulgarian borders, the map is not available at all. In addition, many of the sheets have not been georectified. If you don't know whether your HAGS sheet has been rectified for GPS coordinates, see if it has an orange-color grid over the usual Greek grid. Each map legends, moreover, lists when the map has been checked. This general difficulty with Greek military maps (and things are even worse for Turkish maps) has forced many people to use Landsat, Spot, or Russian satellite scenes, instead.

Military paper maps and satellite images are useful for navigation and accuracy, but they are less useful for database management. In trying to grapple with a site gazetteer for the northwestern Peloponnese, I have concluded that the best solution is to use another set of maps, the 1:250,000 Nomos sheets from the Statistical Service of Greece. These can be bought at the Statistical Service offices near Omonia Square. They are particularly useful because they show the boundaries of Greece's official political units, in descending order from Nomos (province), to Demos (municipality), to Diamerisma (community). The Greek government has given these boundaries to ERSI and are available as shapefiles through an expensive package of ArcGIS. ArcGIS has additional parcels, such as Greek postal codes, which might be equally useful. The nice thing about the Statistical Service shapefiles is that they correspond to the numbering system used by the National Census since the first census of 1963 (the most recent one taken in 2000). For the western Peloponnese, we have wonderful demographic data: an Ottoman census (1461/3), the Corner census (1689), the Grimani census (1700), a continuous series of 19th-c data (Pouqueville, French Expedition to the Morea, etc.), and Greek government data. As far as I know, nobody has put these figures in GIS. With such a database, one can very easily, for example, do dynamic queries about population shifts in the Greek countryside. Demographic changes can also be correlated with topography and natural resources.

GIS requires unique identifiers for every piece of data. Hence, the numbers that correspond to Greece's geographic units are very useful for organizing any site-based table. In descending order, the organizational hierarchy of the Statistical Service is Nomos (Province), Demos (Municipalities), and Diamerisma (Community). The English terms in translation are precisely the ones that ArcGIS uses in their shapefiles. The numbers are consistent and all-inclusive sets. So if you check for village Neohori, where Fred Cooper runs his archaeological field school, you’ll find the following numbers:

Province: 14 (Ilia)

Municipality: 1411 (Zaharo)

Community: 1411130 (Neohori)


The Diamerisma (Community) boundaries are the smallest geographical units defined by Greece. The Nomos (Province) of Eleia, for example, has about 400 parcels. So, if you are making a database of any series of items within that area, you can use the 8-number integer as the prefix. Or if you want to use the larger geographical unit of Demos (Municipality)--about a dozen for each Province)--you can use the 4-number integer as the prefix. Additional numbers can be added for the set of items within that unit.

3 comments:

Simon said...

Hi Kostis! I really appreciated the text you wrote about digital spatial data in Greece and to obtain them. I currently work for an environmental NGO in the Greek archipelago and try to set up some sort of GIS database for future projects. Do you know what national coordinate system is used nowadays and what its parameters are? There is a ready-made projection file in ArcGIS, but I thus far I haven't found any reliable resource confirming it.

siamel AT utu.fi

Greetings!

Simon said...

Hi Kostis! I really appreciated the text you wrote about digital spatial data in Greece and to obtain them. I currently work for an environmental NGO in the Greek archipelago and try to set up some sort of GIS database for future projects. Do you know what national coordinate system is used nowadays and what its parameters are? There is a ready-made projection file in ArcGIS, but I thus far I haven't found any reliable resource confirming it.

siamel AT utu.fi

Greetings!

Anonymous said...

I just ran across this interesting post while searching the web for shapefiles of the Nomoi and Eparchies of Greece. I didn't find any such files, by the way, so if anyone knows of them, can you please let me know?

I wanted to mention another really interesting site which might possibly be helpful to you, Dr. Kourelis, if you don't already know about it. It contains all the Austro-Hungarian military mapping from a series from 1910, including the northern half of Greece. Here is the URL: http://lazarus.elte.hu/hun/digkonyv/topo/3felmeres.htm. It might help with your Serres question.

I also should mention, since I am a US Government employee, that the United States Board on Geographic Names has a free, and quite detailed, gazetteer of Greece. It is available here: http://earth-info.nga.mil/gns/html/index.html. You can put it into any GIS package by using the text import function.

Best wishes, and thanks for this interesting blog,
-Peter Viechnicki

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Kostis Kourelis

Philadelphia, PA, United States