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Thermaikos Gulf coastal system, NW Aegean Sea: an overview of water sediment fluxes in relation to air-land-ocean interactions and human activities

Thermaikos Gulf coastal system, NW Aegean Sea: an overview of water sediment fluxes in relation to air-land-ocean interactions and human activities
Thermaikos Gulf coastal system, NW Aegean Sea: an overview of water sediment fluxes in relation to air-land-ocean interactions and human activities
This study presents an overview of the Holocene formation and evolution of the coastal system of Thermaikos Gulf (NW Aegean Sea). The system is divided into the terrestrial sub-system and the oceanic sub-system; the former represents 90%, while the latter includes only 10% of the total area. This particular coastal zone includes the second most important socio-economic area of Greece and in the southern Balkans, the Thessaloniki region; this is in terms of population concentration (>1 million people), industry, agriculture, aquaculture, trade and services. The geomorphology of the coastal zone is controlled by sediment inputs, nearshore water circulation, and the level of wave activity. The large quantities of sediments (with yields >500 tonnes/km2 per year), delivered annually by the main rivers (Axios, Aliakmon, Pinios, and Gallikos) and other seasonal streams are responsible for the general progradation of the coastline and the formation of the Holocene sedimentary cover over the seabed of the Gulf. Changes to the coastline can be identified on macro- and meso-time scales; the former include the evolution of the deltaic plains (at >1 km2/year), while the latter incorporates seasonal changes along sections of the coastline (e.g. sandy spits), mostly due to the anthropogenic activities. The overall water circulation pattern in Thermaikos Gulf is characterised by northerly water movement, from the central and eastern part of the Gulf; this is compensated by southerly movement along its western part. The prevailing climate (winds and pressure systems) appears to control the surface water circulation, while near-bed current measurements reveal a general moderate (<15 cm/s) southerly flow, i.e. offshore, towards the deep water Sporades Basin. Waves approaching from southerly directions play also a role in controlling the shoreline configuration. Various human activities within the coastal system place considerable pressure on the natural evolution of the coastal zone ecosystem. Thus, the construction of dams along the routes of the main rivers has reduced dramatically the water/sediment fluxes; this caused, for example, retreat of the deltaic coastlines and seawater intrusion into the groundwater aquifers. Similarly, pollution and/or eutrophication of the nearshore marine environment have resulted from the inputs of industrial wastes, urban untreated sewage, and agricultural activities on the coastal plains. This effect is demonstrated by high levels of pollutants, nutrients, and by the increased concentrations of non-residual trace-metals within the surficial sediments. Finally, climatic changes associated with a potential rise in sea level (i.e. 30–50 cm) will threaten a substantial part of the low-lying lands of Thermaikos Gulf. Thus, systematic and thorough monitoring is needed in order to protect the coastal ecosystem; this will ensure its sustainable development and successful management, in relation to present and future socio-economic activities and climatic changes.
THERMAIKOS GULF, AEGEAN SEA, BIOGEOCHEMISTRY, SEDIMENTS, SEDIMENT WATER INTERFACE, NEARSHORE DYNAMICS, AIR SEA INTERACTION, HOLOCENE, COASTAL ZONE, RIVER DISCHARGE
0924-7963
47-76
Poulos, S.E.
9a96cda9-6f05-49ac-a9fa-43002ee2317a
Chronis, G.T.
e16d79e9-2a23-4336-b35e-436314c99ece
Collins, M.B.
3b70278b-0004-45e0-b3c9-0debdf0a9351
Lykousis, V.
ce29036d-416f-4cea-b717-9bd09863b7b7
Poulos, S.E.
9a96cda9-6f05-49ac-a9fa-43002ee2317a
Chronis, G.T.
e16d79e9-2a23-4336-b35e-436314c99ece
Collins, M.B.
3b70278b-0004-45e0-b3c9-0debdf0a9351
Lykousis, V.
ce29036d-416f-4cea-b717-9bd09863b7b7

Poulos, S.E., Chronis, G.T., Collins, M.B. and Lykousis, V. (2000) Thermaikos Gulf coastal system, NW Aegean Sea: an overview of water sediment fluxes in relation to air-land-ocean interactions and human activities. Journal of Marine Systems, 25 (1), 47-76. (doi:10.1016/S0924-7963(00)00008-7).

Record type: Article

Abstract

This study presents an overview of the Holocene formation and evolution of the coastal system of Thermaikos Gulf (NW Aegean Sea). The system is divided into the terrestrial sub-system and the oceanic sub-system; the former represents 90%, while the latter includes only 10% of the total area. This particular coastal zone includes the second most important socio-economic area of Greece and in the southern Balkans, the Thessaloniki region; this is in terms of population concentration (>1 million people), industry, agriculture, aquaculture, trade and services. The geomorphology of the coastal zone is controlled by sediment inputs, nearshore water circulation, and the level of wave activity. The large quantities of sediments (with yields >500 tonnes/km2 per year), delivered annually by the main rivers (Axios, Aliakmon, Pinios, and Gallikos) and other seasonal streams are responsible for the general progradation of the coastline and the formation of the Holocene sedimentary cover over the seabed of the Gulf. Changes to the coastline can be identified on macro- and meso-time scales; the former include the evolution of the deltaic plains (at >1 km2/year), while the latter incorporates seasonal changes along sections of the coastline (e.g. sandy spits), mostly due to the anthropogenic activities. The overall water circulation pattern in Thermaikos Gulf is characterised by northerly water movement, from the central and eastern part of the Gulf; this is compensated by southerly movement along its western part. The prevailing climate (winds and pressure systems) appears to control the surface water circulation, while near-bed current measurements reveal a general moderate (<15 cm/s) southerly flow, i.e. offshore, towards the deep water Sporades Basin. Waves approaching from southerly directions play also a role in controlling the shoreline configuration. Various human activities within the coastal system place considerable pressure on the natural evolution of the coastal zone ecosystem. Thus, the construction of dams along the routes of the main rivers has reduced dramatically the water/sediment fluxes; this caused, for example, retreat of the deltaic coastlines and seawater intrusion into the groundwater aquifers. Similarly, pollution and/or eutrophication of the nearshore marine environment have resulted from the inputs of industrial wastes, urban untreated sewage, and agricultural activities on the coastal plains. This effect is demonstrated by high levels of pollutants, nutrients, and by the increased concentrations of non-residual trace-metals within the surficial sediments. Finally, climatic changes associated with a potential rise in sea level (i.e. 30–50 cm) will threaten a substantial part of the low-lying lands of Thermaikos Gulf. Thus, systematic and thorough monitoring is needed in order to protect the coastal ecosystem; this will ensure its sustainable development and successful management, in relation to present and future socio-economic activities and climatic changes.

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More information

Published date: 2000
Keywords: THERMAIKOS GULF, AEGEAN SEA, BIOGEOCHEMISTRY, SEDIMENTS, SEDIMENT WATER INTERFACE, NEARSHORE DYNAMICS, AIR SEA INTERACTION, HOLOCENE, COASTAL ZONE, RIVER DISCHARGE

Identifiers

Local EPrints ID: 8961
URI: https://eprints.soton.ac.uk/id/eprint/8961
ISSN: 0924-7963
PURE UUID: 2d1caa27-3895-4756-b536-0a82b354fa4b

Catalogue record

Date deposited: 10 Sep 2004
Last modified: 17 Jul 2017 17:12

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