The use of groundwater resources in Zakynthos Island in the Ionian Sea at central Mediterranean has become extremely intensive during the last decades, due to the high rate of urbanisation, tourist development and irrigated land expansion and is estimated being 15 hm
/year. Different methods are being required when water-related sustainability issues are examined like development analysis, quality control processes, application of legal framework and climatic forecasts. In order to aim the water management and improving the sustainability of the groundwater resources of Zakynthos Island, a new water balance has been estimated for each individual watershed after detail hydrological analysis and significant differences were observed from previous estimations being runoff +16.8%, evaporation –13.8 and infiltration –3.1% respectively. A better understanding of the total potential risks regarding future groundwater resources is the critical point for the local authorities to apply a regulatory sustainable plan and the local population to aim for its success.
Keywords: water balance, water management, climatic change, development, Zakynthos, Zante, Ionian Islands, Greece