Karstic spring water quality: the effect of groundwater abstraction from the recharge area

Abstract

Karstic systems are complex hydrogeological systems which are difficult to study due to their complicated function mechanism. This mechanism is even more complex in coastal karstic springs due to sea water intrusion into the system. Modelling of water quality of such coastal karstic springs is a real challenge, which requires an interdisciplinary effort based on hydrodynamic monitoring and accurate characterization of geology and hydrogeology of the system. The paper examines the impact of simultaneous groundwater abstraction from the recharge area of a karstic spring (upstream of the spring) on the water quantity and quality of the spring. The case study examined is Almyros brackish karstic spring in Heraklion, Crete. Based on standard statistical tests of the water quantity and quality indicators time series before and after the initiation of simultaneous groundwater abstraction from the recharge area of the spring, it was concluded that water quality of the spring deteriorates (represented by Cl⁻ concentration) and the quantity decreases for the summer period. However, no statistically significant influence on both quantity and quality was detected during the winter period months.

Keywords:

• Karstic springs
• Brackish water
• Water quality
• Groundwater abstraction
• Reconnaissance Drought Index
• Almyros (Crete) spring

Acknowledgement

The authors wish to thank Dr M. Kritsotakis, Region of Crete, for kindly providing valuable data for this study