The study area of Central Evia belongs to the river basin of Messapios which covers an area of 228.6 sq.km. The relief is high (from sea water level to 1600 m a.s.l.) and the water network is well developed with the river of Messapios crossing the lowlands of the basin.
The geological background of the area consists of Triassic Jurassic and Upper Cretaceous limestone, ophiolites, Neogene marl formations and Quaternary alluvial deposits. In addition, the occurrence of Ni- laterite deposits in proximity to the study area are well known as well as those in Larymna, Central Greece, with a production level corresponding to approximately 2-3 % of the world’s total nickel output.
The study area belongs to the porous groundwater body of Psachna-Politika (EL0700300). Τhe groundwater body of Politika-Psachna has a good quantitative status good in contrast to the qualitative status which is poor because of nitrification and heavy metal contamination. The main aquifers of the wider study area are: a) a shallow unconfined Quaternary porous aquifer (Psachna area), b) a deep Neogene porous aquifer, b) a fractured ophiolitic aquifer and d) a deep karstic aquifer in the Upper Cretaceous limestone. In the lowlands where Psachna town is located, the shallow unconfined aquifer is developed in Quaternary sediments with water level elevation ranging from 2 m to 21 m approximately and main groundwater flow direction from NE to SW.
According to the 2011 Census, the municipality of Messapia has 13,327 permanent residents while Psachna town has 5,827 permanent residents. The main use of groundwater is for irrigation as agricultural activity is intense, and livestock purposes. It is noteworthy that there are outnumbered wells and boreholes which are concentrated in Psachna-Kastella area. As a result, the aquifer is over exploited and sea water intrusion takes place at the coastal zone. Also, industrial activity is not absent in the area as 26 industries (textile, food and olive oil mills) are located in the Politika-Psachna area.