Monitoring physical properties of a submarine groundwater discharge source at Kalogria Bay, SW Peloponnissos, Greece

Hellenic Centre for Marine Research, Institute of Oceanography 46.7 km Athens-Sounio Avenue, 19013 Anavyssos Greece

Abstract

An impressive SGD in Kalogria Bay (SW Peloponnissos) was surveyed for the first time in 2006, revealing the existence of 2 major and 2 minor point sources of freshwater (salinity ~l-2); the discharge was ~ 1000 m³ h⁻¹. The major point source was located in a karstic cavity at 25 m depth. In July 2009, and for a period of one year, the site was monitored intensively. During summer, the underwater discharge was not very strong, the water was flowing from many dispersed points, and salinity range was 20–36. During autumn and winter, flow velocity increased considerably (> 1 m s⁻¹), and the SGDs discharged water of low salinity (< 2). Gradually, the smaller SGDs ceased their operation, and the major SGD emanated brackish water during spring and summer, thus hampering the possibilities of freshwater exploitation, in a touristic area which suffers from great aridity and water demand is high during summer.