Fragilisation et modification des formations littorales meubles sur l’île d’Anjouan (Comores) : Quand l’érosion d'origine anthropique se conjugue au changement climatique

Sinane, Kamardine Mohamed; David, Gilbert; Pennober, Gwenaëlle; Troadec, Roland

doi:10.4000/vertigo.10528

Cited by 10 publications

(6 citation statements)

References 17 publications

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“…The instrument used, called a "topometer" [81,82,83], makes it possible to establish beach profiles with a satisfactory degree of accuracy (Figure 4b). Indeed, the margin of error associated with each measurement is 0.5 cm vertically [43,84]. The difficulty is that this error is cumulative along the profile.…”

Section: Erosion Studymentioning

confidence: 99%

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An orientation for coastal disaster risks management and prevention policy in a global warming context: Case study in Ouvea (New Caledonia)

et al. 2020

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Section: Erosion Studymentioning

confidence: 99%

“…These strategies are increasingly criticised today due to their economic cost, systematic use, which sometimes causes subsequently decisive problems in construction, or their maladaptation to the dynamical context. They imply secondary effects on the environment [40,41,42,43]. These secondary effects can equally occur on a conscious and social level.…”

mentioning

confidence: 99%

An orientation for coastal disaster risks management and prevention policy in a global warming context: Case study in Ouvea (New Caledonia)

et al. 2020

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“…Monnereau and Abraham 2013;Worliczek et al 2010), Indian Ocean (e.g. Sinane et al 2010) and the Caribbean (e.g. Jackson Jr et al 2012;Mycoo and Chadwick 2012).…”

Section: Literature Reviewmentioning

confidence: 99%

“…The Comoros, a small island state in the Channel of Mozambique, faces many environmental challenges. Among other things, coastal erosion and flooding is widespread across the Comorian islands, including on Grande Comore (Abdou Rabi and Ali n.d.;ASCLME 2012;Sinane 2013;Sinane et al 2010) -though precise data on the extent of erosion is lacking (ASCLME 2012). During fieldwork conducted in March 2015, we interviewed national-level stakeholders as well as conducted an informal survey of community members in four different villages on Grande Comore (see figure 1 below and section 3.2) to obtain qualitative insights into local views and experiences regarding coastal erosion and flooding, climate change, and response measures, specifically seawalls, at different levels.…”

Section: Introductionmentioning

confidence: 99%

Seawalls as a response to coastal erosion and flooding: a case study from Grande Comore, Comoros (West Indian Ocean)

Betzold

Mohamed²

2016

Reg Environ Change

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Many coasts are eroding. In the Comoros, as in many other small island developing states (SIDS), communities frequently respond to coastal erosion by building seawalls -yet seawalls and other coastal defence structure are controversial, especially in a SIDS context, where they typically are poorly designed and constructed and thus tend to increase rather decrease erosion and are often unable to prevent flooding.Through an exploratory qualitative case study of Grande Comore, the main island of the Comoros (West Indian Ocean), we compare and contrast how local stakeholders, national elites and donors understand coastal erosion and flooding in the context of a changing climate and how they experience and perceive seawalls as a response measure. Our analysis suggests that although stakeholders are aware of different drivers of coastal erosion and flooding, including sand mining, seawalls are a frequent and customary response to coastal erosion and flooding. Little is known about their disadvantages or alternative response measures, especially among local community members. Further, a lack of capacity and resources leads not only to poorly designed and constructed seawalls but also to difficulties in enforcing rules and regulations such as bans on sand mining.From our exploratory study, three conclusions emerge: (1) local drivers of coastal erosion and flooding are more visible than global climate change while funding is more readily available for adaptation to climate change; (2) a mix of context and site-specific measures would be needed to adequately respond to coastal erosion and flooding -and (3) further information and knowledge about the extent and causes of coastal erosion and flooding as well as about the effects of different response measures would be needed to allow such context and site-specific measures.

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“…The weakening of these natural barriers prevents their attenuation e ciency of coastal hazards such as coastal erosion and marine submersion. Speci c studies on coastal erosion and ooding, coral reef, morphological evolution of beaches, and cyclonic hazard effects highlight the coastal vulnerability (Legoff 2011;Sinane et al 2011;Hauzer et al 2013;Freed and Granek 2014;Ratter et al 2016;Betzold and Mohamed 2017). In contrast, the concept of a Coastal Vulnerability Index (CVI) has been widely used to assess the level of physical vulnerability to sea-level rise.…”

Section: Introductionmentioning

confidence: 99%

A Preliminary Assessment of Coastal Vulnerability For Ngazidja Island, Comoros Archipelago, Western Indian Ocean

Mahamoud

Gzam

Mohamed³

et al. 2021

Preprint

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In previous studies, an emphasis on the particular vulnerability of small island states to future sea-level rise and the intensity of increasing storm surges has been discussed. This preliminary assessment develops a Coastal Vulnerability Index (CVI) along the 202 km long coastline of Ngazidja Island (formerly Grande Comore, Comoros Archipelago), using fieldwork, remote sensing, and geographic information system tools (GIS). The CVI considers five structural variables: (a) geology, (b) geomorphology, (c) topography, (d) shoreline change, and (e) shoreline exposure). It also considers three physical process variables: (f) relative sea-level rise, (g) significant wave height, and (h) mean tide range). The land-use variable was added in this analysis to highlight the human asset exposure in the surrounding areas. Each variable was ranked based on local physical and hydrodynamic conditions and their vulnerability contribution to sea-level rise. The CVI was computed in 270 sections. According to the vulnerability index, approximately 57.5% of the coastline is under low and moderate vulnerability. High and very-high vulnerabilities refer specifically to beaches and shores with old volcanic lava flows located mainly in the northern, northeastern, and southeastern parts of the island, approximately 42.5% of the coastline. The lowest value of CVI is 9.2 on high, rocky cliffs and the highest value is 160 on beaches. This vulnerability partition along the coastline is consistent with in situ indicators of coastal erosion and flooding. In a sea-level rise context, it is of prime importance to integrate coastal vulnerability maps with planning and sustainable management of the coastal zone.

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Fragilisation et modification des formations littorales meubles sur l’île d’Anjouan (Comores) : Quand l’érosion d'origine anthropique se conjugue au changement climatique

Cited by 10 publications

References 17 publications

An orientation for coastal disaster risks management and prevention policy in a global warming context: Case study in Ouvea (New Caledonia)

An orientation for coastal disaster risks management and prevention policy in a global warming context: Case study in Ouvea (New Caledonia)

Seawalls as a response to coastal erosion and flooding: a case study from Grande Comore, Comoros (West Indian Ocean)

A Preliminary Assessment of Coastal Vulnerability For Ngazidja Island, Comoros Archipelago, Western Indian Ocean

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