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July 2003-July 2010InteractiveDig Sagalassos
Véronique and Bert taking soil samples for sedimentological analysis
Overview of the Canaklı Ovası
ASTER satellite image band combination for sedimentolgical interpretation of the Canaklı Ovası

Photos courtesy Sagalassos Archaeological Research Project. Click on images to enlarge.
by Véronique De Laet

Geomorphological Survey: July 20-August 5, 2008

During the second part of the geomorphological survey campaign part of the work of the palaeo-environmental team, composed of Véronique De Laet, Bert Dusar, Johan Bakker, Jozefien Hermy and Jill Haex (all KULeuven), was dedicated to the study of sediment characteristics in the eastern section of the Canaklı Ovası, an intra-mountain basin about 15 km south of Sagalassos (see photograph). In continuation of the 2005 field campaign, when surface soil samples were collected in this area, 2 m deep corings (see photograph) were made to verify the spectral information contained in the ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) and IKONOS satellite imagery. ASTER, an imaging instrument flying on board the TERRA satellite has a spatial resolution of 15 m in the VNIR (Visual near Infrared: 3 spectral bands and 1 stereoscopic band), of 30 m in the SWIR (Short Wave Infrared: 6 bands) and of 90 m in the TIR (Thermal Infrared: 5 bands). The spatial resolution of IKONOS amounts to 1 m for the panchromatic band and 4 m for the multispectral bands (Blue, green, red, NIR). Zones with a different color can be recognized on these images, as is illustrated in the following color image (ASTER image, October 18, 2001). These color variations have most likely a sedimentological, hydrological or vegetation origin. Sometimes these zones are crossing field boundaries, so that a vegetation origin can probably be excluded. A first interpretation of this years corings suggested that there is clear relation between sediment origin and the different zones on the imagery. Color variations are therefore probably related to the development of fans of which the material is originating from different lithological units. This hypothesis will be further tested in the lab and we will examine whether different soil parameters will correlate with the reflectance information contained in the ASTER image. To link the soil samples with the ASTER image, the geographic positions of the different sample locations were measured, using a differential GPS.

To be able to link satellite imagery with other thematic data layers (archaeological data, coring information, GIS layers...) for palaeo-environmental research in the Sagalassos territory, satellite imagery should be georeferenced using accurate ground control points. During this years fieldwork therefore a large number of differentially corrected GPS positions are collected that are evenly distributed over the territory in the X, Y and Z direction. The same points can also be used to create a digital surface model of the territory and the surroundings of Sagalassos.

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