Drought impacts on the fresh water potential of a karst aquifer in Crete, Greece

Abstract

Malia’s coastal aquifer supplies water for domestic and irrigation purposes most of northern part of Heraklion prefecture (central Crete). The extensive exploitation of groundwater since the late 1960s has resulted in a continual decline in groundwater level and significant degradation in groundwater quality, due to salinity intrusion in the coastal aquifer. Moreover, the aquifer will likely to experience impacts of climate-driven recharge changes in the coming years, with adverse consequences for water supply in the region. A regional groundwater flow model was developed to simulate the existing hydrogeological system, and to evaluate the effects of combined impacts of groundwater exploitation and climate variability in future. The investigation results suggest that the equivalent porous medium (EPM) approach appears reasonable for the karst aquifers on a regional scale, as it is capable to simulate the groundwater flow and the spreading of chloride concentration with sufficient accuracy. However, locally the transport of saline water may depend primarily on the karst conduit network rather than matrix permeability; therefore the point information must be evaluated and not taken as undisputed. Furthermore, the study provides a valuable guidance on predicting the seawater intrusion in aquifers under similar hydrogeological conditions; and offers a considerable issue in management of the groundwater quality deterioration.