CIESM - the Mediterranean Marine Research Network

Transformations and evolution of the Mediterranean coastline

F. Briand and A. Maldonado, editors.

CIESM Science Series 3, Bulletin de l'Institut océanographique, Monaco, n° sp. 18.

Summary

The Mediterranean coast: an introduction to the study of coastal changes
Andrés Maldonado
Mobilité verticale des côtes méditerranéennes à la fin de l'Holocène: une comparaison entre données de terrain et modélisation isostatique
Paolo Antonio Pirazzoli
Mediterranean deltas: subsidence as a major control of relative sea-level rise
Daniel Jean Stanley
Coastal changes in western Turkey; rapid delta progradation in historical times
Helmut Brückner
The importance of the river systems in the evolution of the Greek coastline
Serafim E. Poulos and George Th. Chronis
Dynamics and management of sand along the Israeli coastline
Abraham Golik
The role and responsibility of man in the evolution of the Italian Adriatic coast
Umberto Simeoni and Marco Bondesan
Coastal defence by breakwaters and sea-level rise: the case of the Italian northern Adriatic sea
Paolo Colantoni, Giovanni Gabbianelli, Francesco Mancini and Werther Bertoni
The coastline of Albania: morphology, evolution and coastal management issues
Umberto Simeoni, Niko Pano and Paolo Ciavola
Long to short term coastal changes and sediment transport in the Ebro delta; a multi-scale approach
José A. Jiménez, Agustín Sánchez-Arcilla and Andrés Maldonado
Monitoring sea-level rise in the Mediterranean
Susanna Zerbini, Hans-Peter Plag, Bernd Richter and Claudia Romagnoli
Mediterranean coastal biogeomorphology: processes, forms and sea-level indicators
Dieter H. Kelletat
Recent developments of coastal management and sciences in The Netherlands and their potential interest to the Mediterranean
Jean-Marie Stam and Jentje Van der Weide

Preface
by Prof. F. Briand

In April 1996, CIESM organized a special workshop on coastal processes in Ravenna, which highlighted the rapidly changing nature of the Mediterranean shoreline in several sectors of the Basin. The amplitude and major implications of these geomorphological transformations encouraged us to explore the issue further by inviting recognized experts to contribute essays and recent findings on the question in a single volume, the third in the CIESM Science Series. Nearly twenty years have passed since the world was first alerted to the threat of global warming and to the associated risks of sea-level rise. In the ensuing years massive research programmes and highly publicized catastrophic scenarios have done much to make this issue a familiar one to the public at large. If the scientific outcome of global change programmes remains quite debatable ? witness, our frustrating lack of capacity to predict trends and impacts at the local level ? the noise generated by global change issues at least made it easier to launch international initiatives which will monitor sea-level variations at regional scales, using the most accurate remote sensing techniques and ground measurements. There is still no scientific consensus on the rate of sea-level rise expected in the coming century as a consequence of global warming. Some experts project a global sea-level change in the order of 40 cm by the year 2100; others project a rise far in excess of one meter. There is obviously a considerable level of uncertainty in these predictions, but one thing already is certain: low-lying coastal areas worldwide will become inexorably more exposed to sea water intrusion and to storm surges of higher frequency. Against this background the present volume illustrates the dynamic instability of the Mediterranean shoreline in recent geological and historical times. As several chapters make clear, the situation of late has become truely alarming in various sectors of the Mediterranean coast now subjected to unprecedented erosion and tidal flooding. The authors independently agree that the causes are not so much global climatic change and an absolute elevation of the sea, but rather land subsidence originally driven by local tectonics and dramatically aggravated by local human-induced factors. A well documented instance is the northern Adriatic sector, where massive withdrawal of groundwater, oil and gas, extensive sand mining of river beds and beaches, plus the large-scale destruction of natural shoreline defences for urban and touristic development, have all contributed to an unprecedented rise in sea-level in recent years. The figures quoted in this volume are eloquent. For example, in the 1950s, five years of groundwater and methane extraction in the Po delta area sufficed to lower the land by nearly 60 cm. In the Ravenna area, altimetric data reveal that the ground sank for related reasons by more than 125 cm since the 1950s. Knowing that the local geological rate of subsidence approximates 2 mm per year, one can appreciate the added weigh of anthropic factors. Obviously the world-known, dramatic sinking of Venice ? about 25 cm in this century ? is not an isolated episode. Other areas, indeed most coastal plains and large deltas, while not so rich in artistic and architectural heritage, appear no less threatened. Here the destruction of coastal dunes to allow the construction of coastal roads, there massive sand mining, have significantly lowered the natural defences of the coastal ecosystem, irreversibly altering centuries-long equilibria. Often the modifications of the shoreline are only in response to human interventions that occurred hundreds of km away. The book is rich in examples from Albania, Spain, Greece and Italy, demonstrating how river bed mining and river damming have brought about a dramatic reduction in sediment supply to the shore, ultimately accelerating erosion and coastal retreat. Such externalisation of the environmental costs will make it all the more difficult to define, implement and enforce adequate coastal management policies. Yet there is a definite degree of urgency as, in most cases, the future of large population centers is at stake. The tectonics of the Mediterranean plates is quite complex, with land subsiding in places, crustal uplift dominating in others, which prevents any generalization. The fast-changing nature of coastal population dynamics in the region, fueled by migratory fluxes and by anarchic urban and touristic developments, further complicates the picture and renders any hope for a global solution quite illusory. The time now is for a rigorous evaluation of the dramatic mistakes of the past decades, to be followed by local action, both remedial and anticipatory, based on the best monitoring tools and coastal engineering techniques presently available.

My co-editor, Andrés Maldonado, and I are grateful to Christine Poupon and to Anne Toulemont. They took, as usual, the greatest care in overseeing the delicate phases involved in the physical transformation of the manuscripts into the final volume.

	CIESM PUBLICATIONS - Miscellaneous __________________________________________
	Transformations and evolution of the Mediterranean coastline F. Briand and A. Maldonado, editors. CIESM Science Series 3, Bulletin de l'Institut océanographique, Monaco, n° sp. 18. Summary The Mediterranean coast: an introduction to the study of coastal changes Andrés Maldonado Mobilité verticale des côtes méditerranéennes à la fin de l'Holocène: une comparaison entre données de terrain et modélisation isostatique Paolo Antonio Pirazzoli Mediterranean deltas: subsidence as a major control of relative sea-level rise Daniel Jean Stanley Coastal changes in western Turkey; rapid delta progradation in historical times Helmut Brückner The importance of the river systems in the evolution of the Greek coastline Serafim E. Poulos and George Th. Chronis Dynamics and management of sand along the Israeli coastline Abraham Golik The role and responsibility of man in the evolution of the Italian Adriatic coast Umberto Simeoni and Marco Bondesan Coastal defence by breakwaters and sea-level rise: the case of the Italian northern Adriatic sea Paolo Colantoni, Giovanni Gabbianelli, Francesco Mancini and Werther Bertoni The coastline of Albania: morphology, evolution and coastal management issues Umberto Simeoni, Niko Pano and Paolo Ciavola Long to short term coastal changes and sediment transport in the Ebro delta; a multi-scale approach José A. Jiménez, Agustín Sánchez-Arcilla and Andrés Maldonado Monitoring sea-level rise in the Mediterranean Susanna Zerbini, Hans-Peter Plag, Bernd Richter and Claudia Romagnoli Mediterranean coastal biogeomorphology: processes, forms and sea-level indicators Dieter H. Kelletat Recent developments of coastal management and sciences in The Netherlands and their potential interest to the Mediterranean Jean-Marie Stam and Jentje Van der Weide Preface by Prof. F. Briand In April 1996, CIESM organized a special workshop on coastal processes in Ravenna, which highlighted the rapidly changing nature of the Mediterranean shoreline in several sectors of the Basin. The amplitude and major implications of these geomorphological transformations encouraged us to explore the issue further by inviting recognized experts to contribute essays and recent findings on the question in a single volume, the third in the CIESM Science Series. Nearly twenty years have passed since the world was first alerted to the threat of global warming and to the associated risks of sea-level rise. In the ensuing years massive research programmes and highly publicized catastrophic scenarios have done much to make this issue a familiar one to the public at large. If the scientific outcome of global change programmes remains quite debatable ? witness, our frustrating lack of capacity to predict trends and impacts at the local level ? the noise generated by global change issues at least made it easier to launch international initiatives which will monitor sea-level variations at regional scales, using the most accurate remote sensing techniques and ground measurements. There is still no scientific consensus on the rate of sea-level rise expected in the coming century as a consequence of global warming. Some experts project a global sea-level change in the order of 40 cm by the year 2100; others project a rise far in excess of one meter. There is obviously a considerable level of uncertainty in these predictions, but one thing already is certain: low-lying coastal areas worldwide will become inexorably more exposed to sea water intrusion and to storm surges of higher frequency. Against this background the present volume illustrates the dynamic instability of the Mediterranean shoreline in recent geological and historical times. As several chapters make clear, the situation of late has become truely alarming in various sectors of the Mediterranean coast now subjected to unprecedented erosion and tidal flooding. The authors independently agree that the causes are not so much global climatic change and an absolute elevation of the sea, but rather land subsidence originally driven by local tectonics and dramatically aggravated by local human-induced factors. A well documented instance is the northern Adriatic sector, where massive withdrawal of groundwater, oil and gas, extensive sand mining of river beds and beaches, plus the large-scale destruction of natural shoreline defences for urban and touristic development, have all contributed to an unprecedented rise in sea-level in recent years. The figures quoted in this volume are eloquent. For example, in the 1950s, five years of groundwater and methane extraction in the Po delta area sufficed to lower the land by nearly 60 cm. In the Ravenna area, altimetric data reveal that the ground sank for related reasons by more than 125 cm since the 1950s. Knowing that the local geological rate of subsidence approximates 2 mm per year, one can appreciate the added weigh of anthropic factors. Obviously the world-known, dramatic sinking of Venice ? about 25 cm in this century ? is not an isolated episode. Other areas, indeed most coastal plains and large deltas, while not so rich in artistic and architectural heritage, appear no less threatened. Here the destruction of coastal dunes to allow the construction of coastal roads, there massive sand mining, have significantly lowered the natural defences of the coastal ecosystem, irreversibly altering centuries-long equilibria. Often the modifications of the shoreline are only in response to human interventions that occurred hundreds of km away. The book is rich in examples from Albania, Spain, Greece and Italy, demonstrating how river bed mining and river damming have brought about a dramatic reduction in sediment supply to the shore, ultimately accelerating erosion and coastal retreat. Such externalisation of the environmental costs will make it all the more difficult to define, implement and enforce adequate coastal management policies. Yet there is a definite degree of urgency as, in most cases, the future of large population centers is at stake. The tectonics of the Mediterranean plates is quite complex, with land subsiding in places, crustal uplift dominating in others, which prevents any generalization. The fast-changing nature of coastal population dynamics in the region, fueled by migratory fluxes and by anarchic urban and touristic developments, further complicates the picture and renders any hope for a global solution quite illusory. The time now is for a rigorous evaluation of the dramatic mistakes of the past decades, to be followed by local action, both remedial and anticipatory, based on the best monitoring tools and coastal engineering techniques presently available. My co-editor, Andrés Maldonado, and I are grateful to Christine Poupon and to Anne Toulemont. They took, as usual, the greatest care in overseeing the delicate phases involved in the physical transformation of the manuscripts into the final volume.
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