Revista de Gestão Costeira Integrada
Volume 15, Número 1, Março 2015, Páginas 47-63

DOI: 10.5894/rgci490
* Submission: 14 January 2014; Evaluation: 6 February 2014; Reception of revised manuscript: 26 March 2014; Accepted: 3 April 2014; Available on-line: 11 April 2014

Methods for coastal monitoring and erosion risk assessment: two Portuguese case studies *

A. Bio ^{@, a}, L. Bastos ^{a, b}, H. Granja ^{a, c}, J.L.S. Pinho ^d,
J.A. Gonçalves ^{a, b}, R. Henriques ^{c, e}, S. Madeira ^{a, f}, A. Magalhães ^{a, g}, D. Rodrigues ^d

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@ - Corresponding author: [email protected]
a - CIMAR/CIIMAR – Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Rua dos Bragas, 289, 4050-123 Porto, Portugal
b - Departamento de Geociências, Ambiente e Ordenamento do Território, Faculdade de Ciências da Universidade do Porto, Rua Campo Alegre 687, 4169 - 007 Porto, Portugal
c - Department of Earth Sciences, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
d - Department of Civil Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
e - Centro de Geologia da Universidade do Porto, Rua Campo Alegre 687, 4169 - 007 Porto, Portugal
f - Department of Mathematics, Universidade de Trás-os-Montes e Alto Douro, Apartado 1013, 5001-801 Vila Real, Portugal
g - Observatório Astronómico, Faculdade de Ciências da Universidade do Porto, Monte da Virgem, 4430−146 Vila Nova de Gaia, Portugal

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ABSTRACT
Coastal zones are naturally dynamic and mobile systems exposed to natural factors (river flows, waves and storms) as well as human interventions that continuously reshape their morphology. Erosion phenomena related to extreme weather events and sediment scarcity are common, threatening buildings and infrastructures, as well as beaches, ecosystems and valuable wetland; conditions that pose challenges to coastal security and defence. Regular monitoring of coastal areas, assessment of their morphodynamics and identification of the processes influencing sediment transport are thus increasingly important for a better understanding of changes and evolutionary trends in coastal systems. This demands a multi-disciplinary approach involving researchers with expertise in coastal processes and state-of-the-art observation technologies.
In this paper state-of-the-art surveying methods for an efficient quantification of changes in coastal environments are described and evaluated, and two NW-Portuguese case studies are presented. Survey methods included: topographic surveys based on terrestrial videogrammetric mobile mapping and aerial photogrammetry; sub-tidal bathymetry with sonar imagery using an Autonomous Surface Vehicle (ASV); as well as field observations, with sediment sampling and beach characterisation. In the first case study, erosion/accretion patterns in the Douro estuary sand spit were analysed, considering its breakwater, river flow, wave and wind effects. Prior to the construction of a detached breakwater, the spit’s morphodynamics was related to extreme river flow events, wave and wind conditions; afterwards the spit stabilized its shape and increased its area and volume. In the second case study the coast of Vila Nova de Gaia was broadly analysed, including the shoreface, foreshore and dunes, the characterization of major features and a short-period analysis of installed dynamics. Results obtained from field data, topographical surveys and numerical wave models were combined for an erosion risk assessment, using a methodology specifically developed for the study area.
Both monitoring programs achieved their proposed objectives and provided valuable information to the local authorities, as gathered and processed information constitutes a valuable database for coastal planning and for ICZM purposes. They demonstrate the potential of several approaches, supported by advanced technologies, for the study of complex coastal morphodynamic processes.

Keywords: monitoring techniques; Digital Elevation Models; morphodynamics; coastal erosion; risk assessment; Douro Estuary; Vila Nova de Gaia; Portugal.

Métodos de monitorização e análise de risco de erosão costeira: dois casos de estudo portugueses

RESUMO
Zonas costeiras são sistemas naturalmente dinâmicos e móveis, expostos a fatores naturais (fluxos de rios, ondas e tempestades) e intervenções humanas, que alteram continuamente a sua morfologia. Fenómenos de erosão relacionados com temporais e escassez de sedimentos são comuns. Eles ameaçam construções e infraestruturas, praias, ecossistemas e zonas húmidas, o que constitui um desafio para a segurança e defesa costeiras. Uma monitorização regular de áreas costeiras, com avaliação da sua morfodinâmica e identificação dos processos que influenciam o transporte de sedimentos, visando uma melhor compreensão das alterações e tendências evolutivas nos sistemas costeiros, torna-se portanto cada vez mais importante. Para tal necessita-se de uma abordagem multidisciplinar e investigadores especializados em processos costeiros e tecnologias de observação de ponta.
O presente trabalho descreve e avalia métodos de monitorização de última geração para uma quantificação eficiente de alterações em ambientes costeiros e apresenta dois estudos de caso Portugueses. Os métodos de observação incluem: levantamentos topográficos terrestres em modo cinemático baseados em videogrametria; levantamentos topográficos aéreos baseados em fotogrametria; batimetria sub-tidal e imagens de fundo obtidas com sonar a partir de um veículo autónomo de superfície; e observações de campo com análise de sedimentos e caracterização de praias. O primeiro caso de estudo refere-se à análise de padrões de erosão e acreção na restinga do estuário do Douro, tendo em conta efeitos causados pelo molhe, o caudal do rio, ondas e vento. Antes da construção de um molhe destacado, a morfodinâmica da restinga estava relacionada com eventos extremos de caudal, agitação marítima e vento. Após a construção, a forma da restinga estabilizou e observou-se um aumento da sua área e do seu volume. No segundo caso de estudo, a costa de Vila Nova de Gaia foi amplamente estudada, incluindo shoreface, foreshore e dunas, com a caracterização dos principais atributos e uma análise de curto-período da dinâmica instalada. Os resultados obtidos a partir de dados de campo, dos levantamentos topográficos e de modelos numéricos de ondas foram combinados numa análise de risco com métodos especificamente desenvolvidos para a área de estudo.
Ambos os programas de monitorização atingiram os seus objetivos e geraram informação relevante para as autoridades locais. A informação recolhida e processada constitui uma base de dados valiosa para o planeamento costeiro e a Gestão Integrada de Zonas Costeiras. Os estudos demonstram o potencial das diversas abordagens, apoiadas por tecnologias avançadas, para o estudo dos processos complexos de morfodinâmica costeira.

Palavras-chave: técnicas de monitorização; Modelos Digitais de Elevação; morfodinâmica; erosão costeira; análise de risco; estuário do Douro; Vila Nova de Gaia; Portugal.

 

Archetti, R.; Zanuttigh, B. (2010) – Integrated monitoring of the hydro-morphodynamics of a beach protected by low crested detached breakwaters. Coastal Engineering, 57(10):879–891. DOI: 10.1016/j.coastaleng.2010.05.002

Baptista, P.; Bastos, L.; Bernardes, C.; Dias, J. (2008) – Monitoring sandy shores morphologies by DGPS – a practical tool to generate digital elevation models. Journal of Coastal Research, 24(6):1516−1528. DOI: 10.2112/07-0861.1

Barnard, P.L.; Warrick, J.A. (2010) – Dramatic beach and nearshore morphological changes due to extreme flooding at a wave-dominated river mouth. Marine Geology, 271(1-2):131–148. DOI: 10.1016/j.margeo.2010.01.018

Bastos, L; Bio, A; Silva, J.; Pinho, J.L.S.; Granja, H. (2012) – Dynamics of the Douro estuary sand spit before and after breakwater construction. Estuarine, Coastal and Shelf Science, 109:53−69. DOI: 10.1016/j.ecss.2012.05.017

Boak, E.H.; Turner, I.L. (2005) – Shoreline definition and detection: A review. Journal of Coastal Research, 21(4):688−703. DOI: 10.2112/03-0071.1

Brilakis, I.; Fathi, H.; Rashidi, A. (2011) – Progressive 3D reconstruction of infrastructure with videogrammetry. Automation in Construction, 20(7):884−895. DOI: 10.1016/j.autcon.2011.03.005

Consulmar (1996) – Estudos das obras necessárias à melhoria da acessibilidade e das condições de segurança na barra do Douro. Consulmar Report, Administração dos Portos do Douro e Leixões (in Portuguese), Lisboa, Portugal. Unpublished.

Costa, M.; Silva, R.; Vitorino, J. (2001) – Contribuição para o Estudo do Clima de Agitação Marítima na Costa Portuguesa. Actas das 2as Jornadas Portuguesas de Engenharia Costeira e Portuária. Associação Internacional de Navegação, Sines, Portugal (in Portuguese). Available at ftp://ftp.mohid.com/Fortaleza_CD/Bibliografia/Waves/clima_agmar.pdf

Cowart, L.; Walsh, J.P.; Corbett, D.R. (2010) – Analyzing Estuarine Shoreline Change: A Case Study of Cedar Island, North Carolina. Journal of Coastal Research, 26(5):817–830. DOI: 10.2112/JCOASTRES-D-09-00117.1

Cruz, J. (2008) – Ocean Wave Energy. Current Status and Future Perspectives. Green Energy and Technology. 431p., Springer, Berlin. ISBN 978-3-540-74895-3

Dail, H.J.; Merrifield, M.A.; Bevis, M. (2000) – Steep beach morphology changes due to energetic wave forcing. Marine Geology, 162(2-4):443–458. DOI: 10.1016/S0025-3227(99)00072-9

Davidson, M.; Van Koningsveld, M.; de Kruif, A.; Rawson, J.; Holman, R.; Lamberti, A.; Medina, R.; Kroon, A.; Aarninkhof, S. (2007) – The CoastView project: Developing video-derived Coastal State Indicators in support of coastal zone management. Coastal Engineering, 54(6-7):463–475. DOI: 10.1016/j.coastaleng.2007.01.007

Dodet, G.; Bertin, X.; Taborda, R. (2010) – Wave climate variability in the North-East Atlantic Ocean over the last six decades. Ocean Modelling, 31(3-4):120–131. DOI: 10.1016/j.ocemod.2009.10.010

Ferreira, H.; Almeida, C.; Martins, A.; Almeida, J.; Dias, N.; Dias, A.; Silva, E. (2009) – Autonomous bathymetry for risk assessment with ROAZ robotic surface vehicle. OCEANS 2009 IEEE Bremen, 1−6. Available at http://wrem2012.isr.uc.pt/Papers/Ferreira_WREM2012.pdf

Fletcher, C.; Rooney, J.; Barbee, M.; Lim, S.C.; Richmond, B. (2003) – Mapping shoreline change using digital orthophotogrammetry on Maui, Hawaii. Journal of Coastal Research, Special issue 38: 106−124. Available at ftp://ftp.soest.hawaii.edu/coastal/webftp/
JCR_MappingShoreline.pdf

Gonçalves, J.; Bastos, L.; Pinho, J.; Granja, H. (2011) – Digital aerial photography to monitor changes in coastal areas based on direct georeferencing. 5th EARSeL Workshop on Remote Sensing of the Coastal Zone, Prague, June 2011. http://www.conferences.earsel.org/
abstract/show/2689

Granja, H.; Bastos, L.; Pinho, J.; Gonçalves, J.; Henriques, R.; Bio, A.; Magalhães, A. (2011) – Small harbours risks: lowering for fishery and increasing erosion. The case of Portinho da Aguda (NW Portugal). Littoral 2010, 09003, DOI: 10.1051/litt/201109003

Granja, H.M.; Carvalho, G.S. (2000) – Inland beach migration (“beach erosion”) and the coastal zone management (the experience of the northwest coastal zone of Portugal). Periodicum Biologorum, 102(suppl. 1):413–424.

Granja, H.; Pinho, J. L. (2012) – Coastal defense in NW Portugal: the improbable victory. In: Cooper, J.; Pilkey, H. (eds.), The Pitfalls of Shoreline Stabilization, pp. 251−266, Coastal Research Library, vol 3, Springer, USA. ISBN: 978-9400741232. DOI: 10.1007/978-94-007-4123-2_15

Granja H.; Pinho J. L. (in press) – A multi-criteria approach for erosion risk assessment using a new concept of spatial unit analysis, wave model and high resolution DEMs. In: Charles, J.; Finkl, W., Makowski, C. (eds.), Advances in Coastal and Marine Resources: Remote Sensing and Modeling. Coastal Research Library, Springer, USA. ISBN: 978-3319063256.

Harley, M.D.; Turner, I.L.; Short, A.D.; Ranasinghe, R. (2007) – Monitoring beach processes using conventional, RTK-GPS and image-derived survey methods: Narrabeen Beach, Australia. In: Woodroffe, C.D.; Bruce, E.M.; Puotinen, M.; Furness, R.A. (eds.), GIS for the Coastal Zone: A Selection of Papers from CoastGIS 2006, pp. 151–164. University of Wollongong, Australia. ISBN 9781741281378

Hegde, A.V.; Reju, V.R. (2007) – Development of coastal vulnerability index for Mangalore coast, India. Journal of Coastal Research, 23(5):1106–1111. DOI: 10.2112/04-0259.1

Henriques, R. (2004) – SEDMAC/SEDPC: An application to support particle size analysis of unconsolidated sediments. 32nd International Geological Congress, Florence-Italy, abs. 154-6, p. 726.

Holland, K.T.; Vinzon, S.B.; Calliari, L.J. (2009) – A field study of coastal dynamics on a muddy coast offshore of Cassinobeach, Brazil. Continental Shelf Research, 29(3):503–514. DOI: 10.1016/j.csr.2008.09.023

Jacobsen, K. (2000) – User Manual Program System BLUH, 444p., Institute for Photogrammetry and Engineering Surveys, University of Hannover. Available via http://www.ipi.uni-hannover.de/kj.html?&L=1

Kumar, T.S.; Mahendra, R.S.; Nayak, S.; Radhakrishnan, K.; Sahu, K.C. (2010) – Coastal Vulnerability Assessment for Orissa State, East Coast of India. Journal of Coastal Research, 26(3):523−534. DOI: 10.2112/09-1186.1

Loureiro, E. (2006) – Indicadores geomorfológicos e sedimentológicos na avaliação da tendência evolutiva da zona costeira: aplicação ao concelho de Esposende. 329 p., PhD Thesis, Universidade do Minho (in Portuguese). Available at http://hdl.handle.net/1822/7096

Madeira, S. (2007) – Sistema Móvel Terrestre de Levantamento com Integração em SIG. PhD Thesis, Porto University (in Portuguese). Unpublished

Madeira, S.; Gonçalves, J.; Bastos, L. (2009) – Fast Camera Calibration for Low Cost Mobile Mapping. Proceedings of the 6th International Symposium on Mobile Mapping Technology (MMT09), 21−24 July 2009, Presidente Prudente, São Paulo, Brazil. Available at http://docs.fct.unesp.br/departamentos/cartografia/eventos/2009_MMT/
_papers/303_Madeira_MMT09.pdf

Madeira, S.; Gonçalves, J.A.; Bastos, L. (2010) – Photogrammetric mapping and measuring application using MATLAB. Computers and Geosciences, 36(6):699−706. DOI: 10.1016/j.cageo.2009.06.015

Muehe, D. (2011) Erosão Costeira - Tendência ou Eventos Extremos? O Litoral entre Rio de Janeiro e Cabo Frio, Brasil/Coastal Erosion. Revista da Gestão Costeira Integrada, 11(3):315−325. DOI: 10.5894/rgci282

Nawogu, G.; Demirbilek, Z. (2001) – BOUSS-2D: A Boussinesq Wave Model for Coastal Regions and Harbors. Report 1. Theoretical Background and User’s Manual. US Army Corps of Engineers. Engineer Research and Development Center. USA. Available at http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA400294.

Nicholls, R.; Wong, P.; Burkett, V.; Codignotto, J.; Hay, J.; McLean, R.; Woodroffe, S.R.C. (2007) – Coastal systems and low-lying areas. In: Parry, M.; Canziani, O.; Palutikof, J.; Linden, P.V.D.; Hanson, C. (eds.) Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. pp. 315-357, Cambridge University Press, Cambridge, U.K. ISBN 978 0521 88010-7, available at https://www.ipcc.ch/publications_and_data/
publications_ipcc_fourth_assessment_report_wg2_report_impacts_
adaptation_and_vulnerability.htm

Niedermeier, A.; Romaneessen, E.; Lehner, S. (2000) – Detection of coastlines in SAR images using wavelet methods. IEEE Trans. Geoscience and Remote Sensing, 38(5):2270−2281. DOI: 10.1109/36.868884

Niesing, H. (2005) – EUROSION: Coastal erosion measures, knowledge and results acquired through 60 studies. In: Herrier, J.-L.; Mees, J.; Salman, A.; Seys, J.; Van Nieuwenhuyse, H.; Dobbelaere, I. (eds.), Proceedings ‘Dunes and Estuaries 2005’ – International Conference on Nature Restoration Practices in European Coastal Habitats, pp. 421−431, Koksijde, Belgium, 19-23 September 2005, VLIZ Special Publication 19. Available at http://ec.europa.eu/environment/
life/project/Projects/index.cfm?fuseaction=home.showFile&rep=file&fil=
LIFE02_NAT_B_008591_Seminar.pdf

Pendleton, E.A.; Thieler, E.R.; Williams, S.J. (2005) – Coastal Vulnerability Assessment of National Park of American Samoa to Sea-Level Rise. U.S. Geological Survey Open-File Report 2005-1055. Available at http://pubs.usgs.gov/of/2005/1055/images/pdf/report.pdf

Pereira, C.; Coelho, C. (2013) – Mapas de Risco das Zonas Costeiras por Efeito da Ação Energética do Mar. revista de gestão costeira integrada, 13(1):27-43. DOI: 10.5894/rgci325

Pinho, J.L.S. (2001) – Mathematical modelling application to hydrodynamics and water quality studies of coastal zones. PhD Thesis. University of Minho, Braga, Portugal (in Portuguese). Unpublished

Portela, L.I. (2002) – Plano específico de extracção de inertes do rio Douro: caracterização morfodinâmica do estuário do rio Douro. Report 215/02-NEC, 42p., LNEC, Lisbon, Portugal. (in Portuguese).
R Development Core Team (2009) – R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. ISBN 3-900051-07-0. Available at http://www.R-project.org.

Rajawat, A.S.; Bhattacharya, S.; Jain, S.; Gupta, M.; Jayaprasad, P.; Tamilarasan, V.; Ajai; Nayak, S. (2006) – Coastal Vulnerability Mapping for the Indian Coast. Second International Symposium on Geoinformation for Disaster Management.

Rasmussen, D.J.; Holloway, T.; Nemet, G.F. (2011) – Opportunities and challenges in assessing climate change impacts on wind energy – a critical comparison of wind speed projections in California. Environmental Research Letters, 6, 9pp. DOI: 10.1088/1748-9326/6/2/024008.

Rieke-Zapp, D.H.; Nearing M.A. (2005) – Digital Close Range Photogrammetry for Measurement of Soil Erosion. The Photogrammetric Record, 20(109):69−87. DOI: 10.1111/j.1477-9730.2005.00305.x

Rocha, C. P.; Araújo, T.C.M.; Mendonça, F.J.B. (2009) – Aplicação de metodologia alternativa para localizar e monitorar linhas de costa usando técnicas de posicionamento pelo GNSS: Um estudo de caso na praia de Sauaçui, Nordeste do Brasil. revista de gestão costeira integrada, 9(1):93-108. DOI: 10.5894/rgci151

Rosa-Santos P., Veloso-Gomes F., Taveira-Pinto F., Silva R., Pais-Barbosa J., 2009. Evolution of Coastal Works in Portugal and their Interference with Local Morphodynamics, Journal of Coastal Research, Special Issue 56:757-761. Available at http://www.cerf-jcr.org/images/stories/757.761_P.Rosa-Santos_ICS2009.pdf

Short, A.D.; Trembanis, A.C. (2004) – Decadal scale patterns in beach oscillation and rotation Narrabeen Beach, Australia — time series, PCA and wavelet analysis. Journal of Coastal Research 20(2):523−532. DOI: 10.2112/1551-5036(2004)020[0523:DSPIBO]2.0.CO;2

Silva, A.J.R.; Abecasis, C.; Leitão, J.C. (2005) – Improving the navigability and safety conditions in Douro estuary inlet. In: Smith, J.M. (ed.) Coastal Engineering 2004, 19–24 September 2004, vol 3. pp. 3277–3289, World Scientific, Singapore. ISBN: 978-981-256-298-2

Soares de Carvalho, G.; Granja, H.; Costa, A.L. (2006) – Dois casos de mudanças antrópicas na faixa costeira (praias e dunas) do noroeste de Portugal (segmentos costeiros de Leça da Palmeira-estuário do Douro e de Aguda-Espinho). Geonovas 20:13–25.

Souza, C.R. de G.; Luna, G. da C. (2010) – Variação da linha de costa e balanço sedimentar de longo período em praias sob risco muito alto de erosão do município de Caraguatatuba (Litoral Norte de São Paulo, Brasil). revista de gestão costeira integrada 10(2):179-199. DOI: 10.5894/rgci176

Thieler, E.R., 2000. National Assessment of Coastal Vulnerability to Future Sea-Level Rise. USGS Fact Sheet, fs-076-100. Available at http://pubs.usgs.gov/fs/fs76-00/fs076-00.pdf

Thieler, E.R.; Hammar-Klose, E.S. (1999) – National Assessment of Coastal Vulnerability to Sea-Level Rise: Preliminary results for the U.S. Atlantic Coast. U.S. Geological Survey Open-File Report 99–593. Available at http://pubs.usgs.gov/of/1999/of99-593/

Zhu, Z.; Brilakis, I. (2009) – Comparison of optical-sensor-based spatial data collection techniques for civil infrastructure modelling. Journal of Computing in Civil Engineering, 23(3):170–177. DOI: 10.1061/(ASCE)0887-3801(2009)23:3(170)

 

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