Hazard assessment in rock cliffs at Central Algarve (Portugal): A tool for coastal management

Nunes, M.; Ferreira, Óscar; Schaefer, M.; Clifton, Julian; Baily, Brian; Moura, Delminda; Loureiro, Carlos

doi:10.1016/j.ocecoaman.2009.08.004

Cited by 43 publications

(25 citation statements)

References 15 publications

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“…For low retreat rate cliff hazard estimation or assessment, the published work is very scarce and includes expert-based classification of indicators of near future instability (e.g. De Pippo et al, 2008), attempts to characterize the role of sets of conditioning factors, also weighted and combined according to local experience or expert opinion (Del Río and Gracia, 2008;Nunes et al, 2009), and use of Bayesian probabilistic models to forecast future cliff evolution based on past cliff retreat data and expert opinion on a limited set of conditioning factors (Milheiro-Oliveira, 2007;Hapke and Plant, 2010). One of the common shortcomings of these approaches lies in the non-objective assessment of the relative importance of the selected conditioning factors or indicators of future instability.…”

Section: F M S F Marques Et Al: Sea Cliff Instability Susceptibimentioning

confidence: 99%

Sea cliff instability susceptibility at regional scale: a statistically based assessment in the southern Algarve, Portugal

Marques

Matildes

Redweik

2013

Nat. Hazards Earth Syst. Sci.

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Abstract. Sea cliff evolution is dominated by the occurrence of slope mass movements of different types and sizes, which are a considerable source of natural hazard, making their assessment a relevant issue in terms of human loss prevention and land use regulations. To address the assessment of the spatial component of sea cliff hazards, i.e. the susceptibility, a statistically based study was made to assess the capacity of a set of conditioning factors to express the occurrence of sea cliff failures affecting areas located along their top.The study was based on the application of the bivariate information value and multivariate logistic regression statistical methods, using a set of predisposing factors for cliff failures, mainly related to geology (lithology, bedding dip, faults) and geomorphology (maximum and mean slope, height, aspect, plan curvature, toe protection), which were correlated with a photogrammetry-based inventory of cliff failures that occurred in a 60 yr period . The susceptibility models were validated against the inventory data using standard success rate and ROC curves, and provided encouraging results, indicating that the proposed approaches are effective for susceptibility assessment. The results obtained also stress the need for improvement of the predisposing factors to be used in this type of study and the need for detailed and systematic cliff failure inventories.

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Section: F M S F Marques Et Al: Sea Cliff Instability Susceptibimentioning

confidence: 99%

Sea cliff instability susceptibility at regional scale: a statistically based assessment in the southern Algarve, Portugal

Marques

Matildes

Redweik

2013

Nat. Hazards Earth Syst. Sci.

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“…Nunes et al, 2009). In addition, the role of landslides in cliff evolution has been recognized worldwide (e.g.…”

Section: Introductionmentioning

confidence: 99%

Susceptibility assessment to different types of landslides in the coastal cliffs of Lourinhã (Central Portugal)

Epifânio

Zêzere

Neves

2014

Journal of Sea Research

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The coastal zone of Lourinhã (located in Central Portugal) is characterized by beach-cliff systems, where beaches are narrow and cliffs have notorious slope instability. These cliffs evolve by different types of landslides, which are one of the main sources of natural hazard and risk in this coastal region. In this work, aerial photo interpretation and a systematic field survey were performed in order to obtain an inventory of landslides of the following types: rotational slides, translational slides and debris flows. The entire coast was then split into 261 terrain mapping units. For each unit, landslide predisposing factors were derived and classified: cliff elevation, slope angle (maximum, mean and standard deviation), potential solar radiation, slope curvature (profile and plan), lithological units and geologic structure. The predictive susceptibility models were computed for each type of landslide using a bi-variate statistical method -the Information Value Method. The degree of fit and the predictive capacity of the models were assessed using the Effectiveness Ratio, the standard Receiver Operator Characteristic curves and the respective Area Under Curve. Results show that each landslide typology occurs in particular terrain conditions. Individual susceptibility models evidence better predictive capacity than susceptibility model for total landslides.

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“…These two main directions have different energetic conditions that when combined with morphological, lithological, and structural frames determine differential cliff hazard ratings (Nunes et al, 2009) and evolution due to mass movements.…”

Section: Discussionmentioning

confidence: 99%

“…90%) classified as having high or very high susceptibility to cliff erosion (Nunes et al, 2009). The coastline exposes mainly the Miocene Lagos-Portimã o Carbonate Formation (Manuppella, 1992), which is mainly composed of alternating biocalcarenites, siltstones, and limestones, in meter-thick beds, trending up to 10u SW. From W to E the cliffs progressively expose the upper part of the sequence eastward.…”

Section: Study Areamentioning

confidence: 99%

Influence of Wave Action and Lithology on Sea Cliff Mass Movements in Central Algarve Coast, Portugal

Bezerra¹,

Moura²,

Ferreira³

et al. 2011

Journal of Coastal Research

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The vulnerability of a rocky cliff to direct wave attack is a function of its lithological, structural, and morphological characteristics. The intensity of wave attack at the cliff foot depends on incident wave characteristics, nearshore bathymetry, beach and shore platform topography, coastline orientation, storm surges, and tidal range. The main goal of this paper is to relate the role of wave action as a geomorphic process influencing coastal cliff erosion with the control imposed by lithological and structural characteristics. For that purpose, a numerical wave propagation model (STWAVE) was used to evaluate differences in breaking wave height and energy along the study area (Galé-Olhos de Á gua, South Portugal) for a set of representative wave conditions and compared with existing mass movement data. As the study area presents wide longshore variation in wave exposition and breaking wave energies, five sectors were defined with contrasting wave action. When the distribution of mass movements along the coast is analyzed without considering the lithological variation, there is no relationship between the number and displaced volumes of mass movements and wave energy for each sector, with the majority of the movements and the greater volumes occurring in the least energetic sector. Therefore, lithology represents the dominant control on mass movement occurrence. However, if lithological variation is controlled by analyzing only the most common lithology in the study area (Miocene carbonate rocks), spatial variations in nearshore wave energy driven by the interaction of wave conditions with coastline orientation are found to influence mass movement occurrence.www.JCRonline.org ADDITIONAL INDEX WORDS: Wave energy, rocky coasts, wave modeling, rock lithology, volume displaced, erosion, south Portuguese coast.

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Hazard assessment in rock cliffs at Central Algarve (Portugal): A tool for coastal management

Cited by 43 publications

References 15 publications

Sea cliff instability susceptibility at regional scale: a statistically based assessment in the southern Algarve, Portugal

Sea cliff instability susceptibility at regional scale: a statistically based assessment in the southern Algarve, Portugal

Susceptibility assessment to different types of landslides in the coastal cliffs of Lourinhã (Central Portugal)

Influence of Wave Action and Lithology on Sea Cliff Mass Movements in Central Algarve Coast, Portugal

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