Simulation of springs discharge from a karstic aquifer (Crete, Greece), using limited data

Abstract

Five major groups of springs and more than ten pumping wells comprise the main discharge outlets of Agyia karstic aquifer (W. Crete, Greece). The mean annual discharge of the springs is 76 9 10 6 m 3 , while 12 9 10 6 m 3 of water are pumped annually from Myloniana and Agyia's well fields for public water supply and irrigation. The area is almost composed of entirely karstified carbonate rocks (limestones with dolomites), and karstic drainage contributes to infiltration and replenishment of the aquifer. The present work studies the groundwater flow system in the region to investigate the impact of intensive exploitation of the aquifer especially during dry periods (low water table conditions). Due to the lack of sufficient hydrogeologic data, a part of the aquifer extending upwards of Agyia springs was chosen for building the conceptual and numerical model. The groundwater flow was simulated by establishing a reproduction of the measured water heads in the field and the springs discharge. The appropriate set of boundary conditions and the repetition of the model's verification in different dry periods resulted in a sufficiently reliable model. This can be used as a tool to assess different water resource management options during dry periods, when the demand for water is high.