Application of geographic information Systems, ground penetrating radar and transient electromagnetic methods for locating water supply structures at the ancient site of Aptera in Crete

The ancient town of Aptera is located in the western part of the island of Crete. The prominent size of the L-shaped cistern that is visible today suggests an intensive domestic use of water. The existing research on the method of water supply for the cistern is inconclusive. There is no indication of the existence of remnants of either rain harvesting structure or an aqueduct. Therefore it is wide open area for research and field investigations. The developed hypothesis suggests the collection of the surface runoff for filling the cistern.

Developed Geographic Information Systems (GIS) is a terrain-based hydrologic model which outlined a possible drainage area to the main L-shaped cistern in Aptera. When the delineated area was overlain on the contemporary map of Aptera it showed the coincidence between the lower drainage area boundary and the modern road leading to Aptera. The end of the modern road almost touches the corner of the cistern. This coincidence indicates a possibility of the existence of a water supply structure that could be used to fill the cistern with the surface runoff.

We applied two geophysical methods to identify the possible structure: Ground Penetrating Radar (GPR) and the Transient Electromagnetic Method (TEM). Preliminary results show a strong and complementary signal returns along the road from both methods, mapping different depth layers of the subsurface. The combined application of GIS and geophysical methods shows complimentary benefits for locating subsurface features when they are associated with the surface characteristics of the terrain.