International Conference on WAter POllution in natural POrous media at different scales. Assessment of fate, impact and indicators. WAPO 2 BARCELONA (SPAIN) APRIL 11th – 13th, 2007 1 PROPOSED METHOD TO ASSESS THE INTRINSIC GROUNDWATER VULNERABILITY OF SHALLOW AQUIFERS: AN EXAMPLE FROM AMYNTAION BASIN, NORTH GREECE C. Gianneli (1) , K. Voudouris (1) , Ap. Stamos (2) and G. Soulios (1) (1) Lab. of Engineering Geology & Hydrogeology, Aristotle University, Egnatia str. Thessaloniki, 54124 GREECE. E-mail: kvoudour@geo.auth.gr (K. Voudouris, corresponding author) (2) Civil Engineering, Researcher ABSTRACT This work proposes a novel method to assess the intrinsic groundwater vulnerability of shallow aquifers, using hydrogeological and soil data. The study area is located in the Florina prefecture at the northwestern part of Greece, covering the lowlands of the Amyntaion basin. The basin is covered by Quaternary and Neogene deposits, in which a shallow phreatic aquifer have been developed. The aquifer provides water for both domestic and agricultural purposes in the area. The proposed method includes the following parameters: Permeability of the aquifer, Depth to groundwater, Soil type and Cation Exchange Capacity of the vadose zone. The classification of the permeability was based on the geological map and drilling data. The Depth to the water table was extracted from the groundwater level maps. Soil has a significant impact on the amount of recharge which can infiltrate into the ground surface. The Cation Exchange Capacity (CEC) was defined from soil analyses on the basis of the presence of organic material and the soil texture. According to the distribution of the aforementioned parameters thematic maps have been prepared. Using GIS the final groundwater vulnerability map was illustrated. The proposed method is low-cost and can be applied in other areas with similar data availability. Key words: Shallow aquifer, Vulnerability, Amyntaion, Greece 1. INTRODUCTION Many shallow aquifers are developed in alluvial deposits in Greece. The groundwater quality of these aquifers is under many pressures, such as overexploitation, intensive agriculture, land use changes, lack of protection measures etc. Regional assessment of groundwater vulnerability is a useful tool for groundwater resources management and protection (Ibe et al., 2001; Al-Adamat et al., 2003). The vulnerability maps could be used for planning, policy management, contamination assessment, and education. Intrinsic vulnerability is the susceptibility of groundwater to contaminants generated from human activities and takes into account the soil, and the geological and hydrogeological characteristics of an area. It is independent from the nature of the pollutant. Conventional rating methods (i.e. DRASTIC, SINTACS, AVI) have been used to assess the intrinsic groundwater vulnerability (Aller et al., 1987; Civita, 1994; Panagopoulos et al., 2005). This work proposes a novel method to assess the intrinsic groundwater vulnerability of shallow aquifers, using geological and soil data (Holman et al., 2000; Bekesi and McConchie, 2002). The proposed method belongs to the rating methods and includes the parameters: Permeability of the aquifer, Depth to groundwater, Soil type and Cation Exchange Capacity of the vadose zone. Using a Geographical Information System (GIS) the final groundwater vulnerability map was illustrated. This method has been applied in the aquifer system of the Amyntaion basin in NW part of Greece. 2. DESCRIPTION OF THE STUDY AREA The study area is located in the Florina prefecture in the NW part of Greece, covering the boundaries of the Quaternary and Neogene aquifers of the Amyntaion basin (Fig. 1). The altitude of