COASTAL DUNES VULNERABILITY INDEXES: A NEW PROPOSAL

Francisco Sancho, Filipa S. B. F. Oliveira, Paula Freire

Abstract


In the present work it is proposed a new coastal dune vulnerability index based on its exposure (and resistance) to overwashing and erosion under storm events, focusing solely on the short-term events. The methodology is applied and validated against the available data for the Ria Formosa (Algarve, Portugal) coastal beaches. The overwash index is determined as a function of the dune crest height in relation with the maxima water levels for different return periods, and the storm-erosion index is computed as function of the remaining beach/dune volume after the impact of
the 10-year return period extreme-wave conditions in relation to the pre-storm volume. It is discussed the results of this application, enhancing the necessity of further validation.

Keywords


barrier island; maritime-storm; short term; dune-erosion; overwashing; Ancão spit

References


Battjes, J., 1971. Run-up distributions of waves breaking on slopes. J. Waterways, Harbors and Coastal Engineering Division, 97, pp. 91-114.

Capitão, R., F. Sancho, N. Alenquer and B. Proença, 2009. Colmatação de falhas em dados de agitação marítima - o caso de Faro. 6th Jornadas Portuguesas de Engenharia Costeira e Portuária, CDROM, Funchal, 8 e 9 de Outubro de 2009, (in Portuguese).

Coelho, C., R. Silva, F. Veloso-Gomes, F. and Taveira-Pinto, 2006. A vulnerability analysis approach for the Portuguese west coast. In Risk Analysis V: Simulation and Hazard Mitigation, 91, pp. 251–262, (Ed. by V. Popov, and C. A. Brebbia, Wessex Institute of Technology, WIT Transactions on Ecology and the Environment).

Consulmar, Hidroprojecto, Risco, 1989. Estudo do litoral entre o porto de recreio de Vilamoura e o molhe oeste do rio Guadiana. 1ªFase – Estudos de base. Caracterização do regime litoral e detecção dos problemas existentes. Direcção Geral de Portos, 109pp, (in Portuguese).

Costa, M., R. Silva, and J. Vitorino, 2001. Contribuição para o estudo do clima de agitação marítima na costa Portuguesa. 2ªJornadas Portuguesas de Engenharia Costeira e Portuária, Sines, CD-ROM, 20p. (in Portuguese).

Dias, J.A., 1988. Aspectos geológicos do litoral Algarvio. Geonovas, 10, 113–128. (in Portuguese).

Ferreira, Ó., T. Garcia, A. Matias, R. Taborda, and J.A. Dias, 2006. An integrated method for the determination of set-back lines for coastal erosion hazards on sandy shores, Continental Shelf Research, 26:1030-1044.http://dx.doi.org/10.1016/j.csr.2005.12.016

Freire, P., F. Sancho, and F. Oliveira, 2011. Hydrodynamic valorization of Ria Formosa and risk mitigation in the barrier islands; Report 1: risk mitigation in the barrier islands; 1st phase –identification of risk areas. Report 40/2011--EC, L-EC (in Portuguese).

Garcia, T., Ó. Ferreira, A. Matias, and J.A. Dias, 2010. Overwash vulnerability assessment based on long-term washover evolution, -atural Hazards, 54: 225-244.

Holman, R.A., 1986. Extreme value statistics for wave run-up on a natural beach. Coastal Engineering, 9, pp. 527-544.http://dx.doi.org/10.1016/0378-3839(86)90002-5

Holman, R.A., and A.H. Sallenger Jr., 1985. Setup and swash on a natural beach. Journal of Geophysical Research, 90 (C1), pp. 945-953.http://dx.doi.org/10.1029/JC090iC01p00945

Hunt, I.A., 1959. Design of seawalls and breakwaters. J. of Waterways and Harbours Division, ASCE, 85(WW3), pp. 123-152.

Julião, R.P., F. Nery, J.L. Ribeiro, M.C. Branco, J.L. Zêzere, 2009. Guia metodológico para a produção de cartografia municipal de risco e para a criação de sistemas de informação geográfica (SIG) de base municipal. Autoridade Nacional de Protecção Civil, 91p, (in Portuguese).

Masselink, G., and M.G. Hughes, 2003. Introduction to coastal processes and geomorphology. Arnold, London, 354 pp.

Matias, A., Ó. Ferreira, I. Mendes, J.A. Dias, A. Vila-Concejo, 2005. Artificial construction of dunes in the south of Portugal. Journal of Coastal Research, Vol 21, No 3: 472-481http://dx.doi.org/10.2112/03-0047.1

Matias, A., Ó. Ferreira, A. Vila-Concejo, T. Garcia, and J.A. Dias, 2008. Classification of washover dynamics in barriers islands. Geomorphology 97: 655-674.http://dx.doi.org/10.1016/j.geomorph.2007.09.010

Nielsen, P., and D.J. Hanslow, 1991. Wave runup distributions on natural beaches. Journal of Coastal Research, 7 (4), pp. 1139-1152.

Pilkey, O.H., W.J. Neal, J.H. Monteiro, and J.M.A. Dias, 1989. Algarve Barrier Islands: A NoncoastalPlain System in Portugal. Journal of Coastal Research, Vol 5, No 2: 239-261.

Puertos del Estado, 2006. Extremos maximos de nivel del mar (nivel medio horario). Mareografo de Huelva-Mazagón, codigo BD: 3326, Puertos del Estado, Ministerio de Fomento. (in Spanish).

Raubenheimer, B., and R.T. Guza, 1996. Observations and predictions of run-up. Journal of Geophysical Research, 101 (C10), pp. 25575-25587.http://dx.doi.org/10.1029/96JC02432

Roelvink, D., A. Reniers, A. van Dongeren, J.T de Vries, R. McCall, and J. Lescinski, 2009. Modelling storm impacts on beaches, dunes and barrier islands, Coastal Engineering, 56, 1133-1152.http://dx.doi.org/10.1016/j.coastaleng.2009.08.006

Sallenger, A.H., 2000. Storm impact scale for barrier islands, Journal of Coastal Research, 16(3):890-895.

Seabra de Melo, J.L.B., 1989. Caracterização hidro-oceanográfica da Ria Formosa. Anais do Instituto Hidrográfico, n.º 10, pp. 7-23 (in Portuguese).

Stockdon, H.F., R.A. Holman, P.A. Howd, and A.H. Sallenger Jr., 2006. Empirical parameterization of setup, swash and runup. Coastal Engineering, 53, pp. 573-588.http://dx.doi.org/10.1016/j.coastaleng.2005.12.005

Teixeira, S., 2009. "Demarcação do leito e da margem das águas do mar no litoral sul do Algarve". ARH Algarve, Departamento de Recursos Hídricos do Litoral, 207 pp., (in Portuguese).

Teixeira, S., 2010. Inundation risk at the Ria Formosa coast. ARH Algarve, Departamento de Recursos Hídricos do Litoral. Relatório Provisório, Faro, Abril 2010, 40 pp., (in Portuguese).

Vila-Concejo, A., A. Matias, A. Pacheco, Ó. Ferreira, and J.A. Dias, 2006. Quantification of inletrelated hazards in barrier island systems. An example from the Ria Formosa (Portugal), Continental Shelf Research: 26:1045-1060.http://dx.doi.org/10.1016/j.csr.2005.12.014

Williams, A.T., J. Alveirinho-Dias, F. García Nove, M.R. García Mora, R. Curr, and A. Pereira, 2001. Integrated coastal dune management: checklist. Continental Shelf Res., 21, 1937-1960.


Full Text: PDF

Creative Commons License
This work is licensed under a Creative Commons Attribution 3.0 License.