Greek case studies: The implications of the expected sea level rise on the low lying areas of continental Greece in the next century
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The implications of the expected sea level rise on the low lying areas of continental Greece in the next century
A natural hazard that is expected to influence on a global scale the earth’s coastal zones in the near future, is the increased rate of sea level rise caused by the continental and glacier ice melt and expansion of the oceanic water masses triggered by a rise in air temperature due to the Greenhouse effect. Based on world-wide climatic data of the U.S. Environmental Protection Agency and the use of mathematical models, it is estimated that by the year 2050, the temperature will rise by 1°C and sea level will be 15 cm higher, while by the year 2100 the temperature will be 2°C higher than today and sea level will have risen by about 34 cm. The rate of sea level rise will be 4,2 mm/year in 2100. In the case of deltaic deposits, an additional land subsidence due to sediment compaction should be taken into account.
Given the extensive stretches of low lying coastal areas of continental Greece in the form of deltas, lagoons, coastal alluvial plains and pocket beaches and their significant settlement, tourist and industrial development in the last decades, the implications of the expected sea level rise are examined for the coasts of continental Greece. Furthermore, the specific economic and social implications of the land use pattern of the coastal zones such as farmland, salt pans, fisheries, tourist installations, airports, etc. are also studied.
Human interference has influenced the natural evolution of both the coastal and the fluvial environments. An almost certain sea level rise will enhance the risks threatening the resilience of coasts and rivers. River channel diversions or cut-offs, irrigation, hydroelectric or regulation dams as well as coastal works such as jetties, wharfs, piers, landfills, highways, harbours and marinas constitute important elements that disrupt the coastal environment.
Coastal classification of Continental Greece
The coastline of continental Greece has not only a great length but also a complex configuration. The distinct features of Greek coastal zones can be classified as deltaic plains, lagoons, coastal plains, pocket beaches and steep coasts.
The length of the coastline for the five aforementioned categories of continental Greece has been estimated at scale 1:50000, see Fig. 1. The coastline corresponding to steep coasts represents 48,04 % of the total length, coastal plains 38,27%, deltaic plains 6,39 %, lagoons 3,73 % and pocket beaches 3,57 %.
Expected sea level rise in the next 100 years
Given the vulnerability of low lying coastal areas to an expected sea level rise in the next 100 years, four deltaic plains were studied, namely Sperkhios, Evinos, Arakhthos and Kalamas. Using topographic maps at a scale 1:5000 and delineating the land below the 0.50 m contour line, the area that will be inundated by the sea by the year 2100 was calculated. In these 50 cm an anticipated sea level rise of 0.34 m by EPA (1995) is included together with more than 0.15 m of natural sediment compaction of the deltas (Fig. 3).
Considering together the 15 most important deltaic plains of continental Greece (Kalamas, Louros, Arakhthos, Akheloos, Evinos, Mornos, Pinios of Peloponnesus, Alfios, Sperkhios, Pinios of Thessaly, Aliakmonas, Axios, Strymonas, Nestos and Evros) we find that about 306,63 km2 of land will be lost by the year 2100, i.e. 13,16% of these plains are expected to be covered by the sea.
In the case of the coastal plains, it is estimated that negligible amounts of land will be lost to the sea mainly due to steeper slopes and a narrower plain. In northern and western Peloponnesus, for instance, the coastline retreat will be insignificant due to the high elevations and slopes of the dunes and alluvial cones and fans. Coastal wetlands will be covered by the rising sea and this important natural resource of the environment of Greece will diminish greatly or even cease to exist. The lagoons of Kotyhi, Messologi, Amvrakikos, and Porto Lagos, which are important fishing grounds, will become shallow bays or gulfs. The extensive salt pans of Messologi and other areas of Greece will have to move farther inland.
References
Karybalis, E. 1996. Geomorphologic observations in the drainage basin of Evinos river, Ph.D. University of Athens (In Greek).
Maroukian H, 1990. Implications of sea level rise for Greece, Report of the I.P.C.G., Miami Conference, vol.2, pp. 161-181.
Maroukian, H., K. Gaki-Papanastasssiou, K. Pavlopoulos & A. Zamani 1995. Comparative geomorphological observations in the Kalamas delta in western Greece and the Sperkhios delta in eastern Greece. Rapp.Comm.int. Mer. Medit., 34, 110 (Abstract).
Maroukian, H., K. Gaki-Papanastassiou, K. Pavlopoulos, & V. Sabot 2004. The assumed future sea level rise as a natural Hazard threatening the coastlines of continental Greece. AGPH, v. XXXX, pp. 69-82.
Moutzouris, K. & H. Maroukian 1988. Greece In: Artificial Structures and Shorelines. H. J. Walker ed. New York: Academic Publishers, pp. 207-215.
Titus G.J. & V.K. Narayanan 1995. The probability of sea level rise. U.S. E.P.A., Washignton D.C.
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