Erosion and Management in Coastal Dunes
This chapter summarizes the concepts of geomorphology and ecology in coastal dunes and analyzes the environmental variables that regulate its functioning, development and evolution. It also discusses the responses to global and local climate change at dif
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Erosion and Management in Coastal Dunes Silvia Cristina Marcomini and Ruben Alvaro Lo´pez
Abstract This chapter summarizes the concepts of geomorphology and ecology in coastal dunes and analyzes the environmental variables that regulate its functioning, development and evolution. It also discusses the responses to global and local climate change at different scales of time (from years to centuries) and their response in the geomorphological and ecological conditions. Then we synthesized the action of man in modifying coastal dunes and the causes and consequences that lead to alterations in the coastal dynamics, enhancing the erosion phenomenon. Finally, we show and discuss appropriate management strategies for coastal dunes and raised suitable methodologies for coastal protection, beach remediation and reconstruction of the foredune.
19.1
Introduction
Coastal sand dunes are unique and complex systems. They are widely distributed environments in the world and occur in almost every latitude – from tropical to polar. Dune systems are of great value to society because they act as natural sea defenses, wildlife refuges and recreational areas. On the Atlantic coast of South America dune systems are very common and much of the population has settled on them without knowledge of the aeolian aerodynamic and its relation to coastal hydrodynamics. In southern Brazil, Uruguay and northeastern Argentina coastal dune fields are associated with Holocene barriers composed of unconsolidated sand, and are therefore highly vulnerable to erosion (Tomazelli and Villwock 2000; Tomazelli et al. 1999; Toldo et al. 1999;
S.C. Marcomini (*) • R.A. Lo´pez Facultad de Ciencias Exactas y Naturales, Departamento de Geologı´a, Universidad de Buenos Aires, Buenos Aires, Argentina e-mail: [email protected]; [email protected] C.W. Finkl (ed.), Coastal Hazards, Coastal Research Library 6, 511 DOI 10.1007/978-94-007-5234-4_19, # Springer Science+Business Media Dordrecht 2013
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Gruber et al. 2003; Dillenburg et al. 2000, 2005). Transgressive dune fields are also frequently hanging on cliffs whose dynamics are controlled by aeolian ramps. Dune coasts are very sensitive to climate changes especially in relation to wind regime, rainfall, water-table and sea level variations that condition dune activity by changes in the sand supply to the littoral system. Natural ecosystems that settle on such environments should develop adaptive strategies to survive under environmental stress. Man initially considered dunes to be unproductive environments, but was then required to find adaptive strategies to settle on them, including the stabilization of dune fields by afforestation for further urban development. Human intervention has altered the rates of aeolian and marine sediment supply to coastal zones, intensifying foredune erosion and degradation. Dune coasts are highly vulnerable to erosion due to lack of compaction of aeolian deposits and often, once the process starts, it is irreversible. This chapter describes t
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