S layer represents soil media with direct assignment of S index values (Soil Map of Greece 1:500.000)

T layer represents topographical information, where calculation of the slope was effectuated and represented in rasterfile, reclassified into T index values.

Vulnerability assessment output map using DRASTIC method (Aller et al., 1987)

I layer represents direct assignment of I index values for the only each hydrological unit.

C layer represents hydraulic conductivity of hydrological units and direct assignment of C index to each aquifer.

Vulnerability assessment using DRASTIC method (Aller et al., 1987)

R layer represents net recharge to groundwater (1980-2000 data).

A layer represents aquifer media with direct of assignment of A index values for each aquifer delimitated (geological map of Atalanti 1:50.000 HSGME).