Greek case studies: The implications of the expected sea level rise on the low lying areas of continental Greece in the next century
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 in the near future, is the anticipated rapid sea level rise by the to 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 calculated that by the year 2050, the temperature will rise by 1C and sea level will be 15 cm higher while by the year 2100 the temperature will be 2C higher than today and sea level will have risen by about 34 cm. Thus, 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 that continental Greece possesses 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, saltworks, fisheries, tourist installations, airports, etc. are also studied.
Human interference has influenced the natural evolution not only of the coastal environment but also the fluvial. An almost certain sea level rise will enhance the risks involved in the well-being of the coasts and the 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 presents not only a great length but also a complex configuration. It is possible to group them in deltaic plains, lagoons, coastal plains, pocket beaches and steep coasts
Coastal classification of Continental Greece. We measured the coastal lengths of the five aforementioned categories of continental Greece at scale 1:50000. The coastal lengths correspond to steep coasts (48,04 %), coastal plains (38,27%) and to a much lesser degree, deltaic plains (6,39 %), lagoons (3,73 %) and pocket beaches (3,57 %) (fig 1.).
The distribution of the five coastal types by geographical department. Worthnoting is the great extent of low lying coasts (deltaic plains and lagoons) in Thrace (88 %). On the contrary, the steep coasts comprise about 2/3 of the coasts of Thessaly. The main region where deltaic plains have considerable extend are in Epirus (24,23%, Kalamas - Arakhthos and in Thrace (25,69 %, Evros).
Expected sea level rise in the next 100 years
Given the vulnerability of low lying coastal areas by 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).
Generalizing for 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) and applying the mean land expected to be covered by the sea (13,16%), we come to the conclusion that about 306,63 km2 of land will be lost by the year 2100. In the case of the coastal plains, it is estimated and hoped that negligible amounts of land will be lost to the sea mainly due to steeper slopes and narrower land. In northern and western Peloponnesus for example, the coastline retreat will be insignificant due to the high elevations and slopes of the dunes and alluvial cones and fans. Costal wetlands will be covered by the rising sea level and an important natural resource of the environment of Greece will diminish dramatically cease to exist. The lagoons of Kotyhi, Messologi, Amvrakikos, and Porto Lagos that are important fishing grounds, will become shallow bays or gulfs. The extensive saltworks of Messologi and other areas of Greece will have to move farther inland.
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