Study site description: Nestos River Delta, Maggana, Greece

Table of Contents

1. Responsible partner
2. General information
3. Bio-physical description
   1. Land use
   2. Climate
   3. Geology
   4. Hydrogeology
   5. Water resources
   6. Soil salinization
4. Socio-economic description
5. Institutional and political setting
6. Relevant end-users / stakeholder groups
7. Past and on-going projects

Hydrogeology

The structure and the constitution of the materials of delta's plain region, directly affect the hydrogeological model. Two distinct hydrogeological systems are formed within the alluvial deposits of the wider study area:

• The shallow system, consisting of phreatic and mostly of semi-confined aquifers extends down to a depth of approximately 30m. Natural recharge to this system originates mostly from the infiltration of rainfall and less from the stream percolation of the northern hilly area. During the last decade, a great amount of small diameter shallow wells (up to 15m depth) were set in operation. Nowadays, only few of them are still working, whilst most of them have been replaced by deeper wells (up to 50m depth).
• The deeper aquifer system consists of confined aquifers, extended to a depth of at least 190m. Natural recharge to this system originates to a great extent from the Nestos river, through buried old stream beds, and from the lateral groundwater inflows coming from the adjacent hydrogeological basin of Vistonida Lake.

Research conducted by our group (including the study of borehole data, geophysical research and lithological studies) revealed that the recent sediments upon which the study site area lies, have a thickness of a few tens of meters. Up to 30m, alternations of sands and clays can be found with a predominance of sands. Then a layer of marly materials is interfering, with a thickness of over 50m, followed by alternations of clayey and sandy layers. In the central region of the study site, where marshy areas were located in the past, clay materials prevail from the surface up to 60m deep (with the exception of the first 2m), while deeper in the profile (up to the 115m) clays mixed with sand and gravel were detected. The deeper aquifer system however is not significantly affected by sea intrusion, although it is mainly located to a depth of more than 115m. The southern part of the study site consists of permeable materials with alternations of river-torrent and marine deposits.