In Maldives, 39 islands are significantly damaged among 200 inhabited islands and nearly a third ... more In Maldives, 39 islands are significantly damaged among 200 inhabited islands and nearly a third of the Maldivian people are severely affected by the Indian Ocean Tsunami in 26 December 2004. We surveyed tsunami impact in 43 islands by measuring island topography and run-up height, interview to local people and mapping of the flooded and destructed areas. The differences in tsunami height and disaster corresponding to the atoll shape and island topography are observed. In the northern atolls, atoll rims consist of many ring-shaped reefs, i.e. miniature atolls called `faro', and interrupted many channels between them. The interrupted atoll rim may play an important role to reducing tsunami run-up height. Severe damage was not observed in the eastern coast of the islands. Beach ridge also contribute to the protection against tsunami. However, in some islands, houses beside the lagoon are damaged by backwashing floodwater from the lagoon. Water marks show the run-up height of -1.8m above MSL. The lagoon water-level seems to set-up by tsunami which permeates into the lagoon through the interrupted atoll rim. The disaster was severe at the southern atolls of Meemu, Thaa and Laamu. The higher run-up heights of up to 3.2m above MSL and enormous building damages were observed at the islands on the eastern atoll rims. The continuous atoll rim of these atolls may reinforce tsunami impact at the eastern islands. In addition, tsunami surge washed the islands totally because of low island topography without beach ridge. Significant floodwater from lagoon was not observed in these atolls. It seems the lagoon water-level was not set-up largely. The continuous atoll rim reduces the tsunami influence to the lagoon and the western side of the atolls. The continuity of atoll rim is probably the major factor to cause the difference in water movement, i.e. tsunami run-up and lagoon set-up, which affects the disaster in the islands. Beach ridge contribute to reduce the tsunami impact to the settlement and agricultural land. Our results may elucidate secure atoll and island type to mitigate the risk of future tsunamis on atoll nations/districts in the Pacific and the Indian Ocean.
This study deals with the "safer island concept" implemented for the reconstruction and... more This study deals with the "safer island concept" implemented for the reconstruction and rehabilitation works after the 26 December 2004 Indian Ocean Tsunami in the Maldives. The safer island concept has been developed as an important adaptation strategy for tsunamis as well as the sea-level rise due to climate change. Reconstruction work in Dhuvaafaru Island to rehabilitate the entire population of Kandholhudhoo Island of Raa atoll is chosen as a case study. The appropriateness of the functionality of the redesigned island to provide security and safety for the island communities is evaluated using the digital elevation model. The study results show that the design enhanced mitigation measures of the island might show some resilience for less frequent natural disasters such as smaller tsunamis, while the implementation of the concept may create greater vulnerability for more frequent disasters, such as flash floods and storms. An integrated approach with appropriate risk a...
Die Dokumente in HENRY stehen unter der Creative Commons Lizenz CC BY 4.0, sofern keine abweichen... more Die Dokumente in HENRY stehen unter der Creative Commons Lizenz CC BY 4.0, sofern keine abweichenden Nutzungsbedingungen getroffen wurden. Damit ist sowohl die kommerzielle Nutzung als auch das Teilen, die Weiterbearbeitung und Speicherung erlaubt. Das Verwenden und das Bearbeiten stehen unter der Bedingung der Namensnennung. Im Einzelfall kann eine restriktivere Lizenz gelten; dann gelten abweichend von den obigen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. Documents in HENRY are made available under the Creative Commons License CC BY 4.0, if no other license is applicable. Under CC BY 4.0 commercial use and sharing, remixing, transforming, and building upon the material of the work is permitted. In some cases a different, more restrictive license may apply; if applicable the terms of the restrictive license will be binding.
Bulletin of Engineering Geology and the Environment, 2010
This paper discusses the influence of the geological setting of islands and reefs in the Maldives... more This paper discusses the influence of the geological setting of islands and reefs in the Maldives on the impact of the 26 December 2004 Indian Ocean Tsunami. Geological and geomorphological data (including orientation, location, size, ellipticity, reef-island distance, proportion of reef area to island area) were collected for completely flooded and \25% flooded islands. The results show that although the different parameters may interact to reduce or magnify the impact, the reef-island distance is the most important factor. The critical minimum distance between the reef and the island shoreline required for the wave to set up is estimated as 89 m on the eastern and 140 m on the western sides of the island, respectively. Circular islands with short reef-island distance and small percent of reef area seem to be safer in the context of tsunami. The result of this study can be applied to identify islands that are naturally protected/resilient against natural disasters such as tsunami and those where the hazard is greatest.
• The Republic of Maldives is one of the most biodiverse countries in the world, yet it is among ... more • The Republic of Maldives is one of the most biodiverse countries in the world, yet it is among the most vulnerable to climate change. The country needs to ensure the sustainable management of natural resources in spite of the impacts and consequences of climate change.
This study presents a tsunami hazard analysis for the Maldives using integrated statistical appro... more This study presents a tsunami hazard analysis for the Maldives using integrated statistical approaches, such as the WE (weight of evidence) method and a LR (logistic regression) model, using historical flooding records from the Maldives following the 2004 Indian Ocean Tsunami. The data with respect to the geological and geomorphological parameters of the islands and reefs, which were collected from 202 inhabited islands and seven resorts in the Maldives, were weighted by the presence/absence of evidence from the impacted islands. The tsunami hazard and risk were evaluated using spatial weights calculated for each variable. The predicted tsunami risk was compared with the impact of the 2004 Indian Ocean Tsunami. The results show that for the three cases, the success rate of the estimated hazard and risk prediction ranged between 74% and 90% for the low and high impact islands, respectively. However, the predictability for medium impact islands in the three cases was within the range ...
The 2004 Indian Ocean tsunami was one of the most devastating tsunamis in world history. The tsun... more The 2004 Indian Ocean tsunami was one of the most devastating tsunamis in world history. The tsunami caused damage to most of the Asian and other countries bordering the Indian Ocean. After a decade, reconstruction has been completed with different levels of tsunami countermeasures in most areas; however, some land use planning using probabilistic tsunami hazard maps and vulnerabilities should be addressed to prepare for future tsunamis. Examples of early-stage reconstruction are herein provided alongside a summary of some of the major tsunamis that have occurred since 2004, revealing the tsunami countermeasures established during the reconstruction period. Our primary objective is to report on and discuss the vulnerabilities found during our field visits to the tsunami-affected countries-namely, Indonesia, Sri Lanka, Thailand and the Maldives. For each country, future challenges based on current tsunami countermeasures, such as land use planning, warning systems, evacuation facilities, disaster education and disaster monuments are explained. The problem of traffic jams during tsunami evacuations, especially in well-known tourist areas, was found to be the most common problem faced by all of the countries. The readiness of tsunami warning systems differed across the countries studied. These systems are generally sufficient on a national level, but local hazards require greater study. Disaster reduction education that would help to maintain high tsunami awareness is well established in most countries. Some geological evidence is well preserved even after a decade. Conversely, the maintenance of monuments to the 2004 tsunami appears to be a serious problem. Finally, the reconstruction progress was evaluated based on the experiences of disaster reconstruction in Japan. All vulnerabilities discussed here should be addressed to create longterm, disaster-resilient communities.
This study deals with the "safer island concept" implemented for the re... more This study deals with the "safer island concept" implemented for the reconstruction and rehabilitation works after the 26 December 2004 Indian Ocean Tsunami in the Maldives. The safer island concept has been developed as an important adaptation strategy for tsunamis as well as the sea-level rise due to climate change. Reconstruction work in Dhuvaafaru Island to rehabilitate the entire population of Kandholhudhoo Island of Raa atoll is chosen as a case study. The appropriateness of the functionality of the redesigned island to provide security and safety for the island communities is evaluated using the digital elevation model. The study results show that the design enhanced mitigation measures of the island might show some resilience for less frequent natural disasters such as smaller tsunamis, while the implementation of the concept may create greater vulnerability for more frequent disasters, such as flash floods and storms. An integrated approach with appropriate risk assessment of floods, storms, and other physical aspects of the island is recommended for the future development of the safer island concept.
In Maldives, 39 islands are significantly damaged among 200 inhabited islands and nearly a third ... more In Maldives, 39 islands are significantly damaged among 200 inhabited islands and nearly a third of the Maldivian people are severely affected by the Indian Ocean Tsunami in 26 December 2004. We surveyed tsunami impact in 43 islands by measuring island topography and run-up height, interview to local people and mapping of the flooded and destructed areas. The differences in tsunami height and disaster corresponding to the atoll shape and island topography are observed. In the northern atolls, atoll rims consist of many ring-shaped reefs, i.e. miniature atolls called `faro', and interrupted many channels between them. The interrupted atoll rim may play an important role to reducing tsunami run-up height. Severe damage was not observed in the eastern coast of the islands. Beach ridge also contribute to the protection against tsunami. However, in some islands, houses beside the lagoon are damaged by backwashing floodwater from the lagoon. Water marks show the run-up height of -1.8m above MSL. The lagoon water-level seems to set-up by tsunami which permeates into the lagoon through the interrupted atoll rim. The disaster was severe at the southern atolls of Meemu, Thaa and Laamu. The higher run-up heights of up to 3.2m above MSL and enormous building damages were observed at the islands on the eastern atoll rims. The continuous atoll rim of these atolls may reinforce tsunami impact at the eastern islands. In addition, tsunami surge washed the islands totally because of low island topography without beach ridge. Significant floodwater from lagoon was not observed in these atolls. It seems the lagoon water-level was not set-up largely. The continuous atoll rim reduces the tsunami influence to the lagoon and the western side of the atolls. The continuity of atoll rim is probably the major factor to cause the difference in water movement, i.e. tsunami run-up and lagoon set-up, which affects the disaster in the islands. Beach ridge contribute to reduce the tsunami impact to the settlement and agricultural land. Our results may elucidate secure atoll and island type to mitigate the risk of future tsunamis on atoll nations/districts in the Pacific and the Indian Ocean.
This study deals with the "safer island concept" implemented for the reconstruction and... more This study deals with the "safer island concept" implemented for the reconstruction and rehabilitation works after the 26 December 2004 Indian Ocean Tsunami in the Maldives. The safer island concept has been developed as an important adaptation strategy for tsunamis as well as the sea-level rise due to climate change. Reconstruction work in Dhuvaafaru Island to rehabilitate the entire population of Kandholhudhoo Island of Raa atoll is chosen as a case study. The appropriateness of the functionality of the redesigned island to provide security and safety for the island communities is evaluated using the digital elevation model. The study results show that the design enhanced mitigation measures of the island might show some resilience for less frequent natural disasters such as smaller tsunamis, while the implementation of the concept may create greater vulnerability for more frequent disasters, such as flash floods and storms. An integrated approach with appropriate risk a...
Die Dokumente in HENRY stehen unter der Creative Commons Lizenz CC BY 4.0, sofern keine abweichen... more Die Dokumente in HENRY stehen unter der Creative Commons Lizenz CC BY 4.0, sofern keine abweichenden Nutzungsbedingungen getroffen wurden. Damit ist sowohl die kommerzielle Nutzung als auch das Teilen, die Weiterbearbeitung und Speicherung erlaubt. Das Verwenden und das Bearbeiten stehen unter der Bedingung der Namensnennung. Im Einzelfall kann eine restriktivere Lizenz gelten; dann gelten abweichend von den obigen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. Documents in HENRY are made available under the Creative Commons License CC BY 4.0, if no other license is applicable. Under CC BY 4.0 commercial use and sharing, remixing, transforming, and building upon the material of the work is permitted. In some cases a different, more restrictive license may apply; if applicable the terms of the restrictive license will be binding.
Bulletin of Engineering Geology and the Environment, 2010
This paper discusses the influence of the geological setting of islands and reefs in the Maldives... more This paper discusses the influence of the geological setting of islands and reefs in the Maldives on the impact of the 26 December 2004 Indian Ocean Tsunami. Geological and geomorphological data (including orientation, location, size, ellipticity, reef-island distance, proportion of reef area to island area) were collected for completely flooded and \25% flooded islands. The results show that although the different parameters may interact to reduce or magnify the impact, the reef-island distance is the most important factor. The critical minimum distance between the reef and the island shoreline required for the wave to set up is estimated as 89 m on the eastern and 140 m on the western sides of the island, respectively. Circular islands with short reef-island distance and small percent of reef area seem to be safer in the context of tsunami. The result of this study can be applied to identify islands that are naturally protected/resilient against natural disasters such as tsunami and those where the hazard is greatest.
• The Republic of Maldives is one of the most biodiverse countries in the world, yet it is among ... more • The Republic of Maldives is one of the most biodiverse countries in the world, yet it is among the most vulnerable to climate change. The country needs to ensure the sustainable management of natural resources in spite of the impacts and consequences of climate change.
This study presents a tsunami hazard analysis for the Maldives using integrated statistical appro... more This study presents a tsunami hazard analysis for the Maldives using integrated statistical approaches, such as the WE (weight of evidence) method and a LR (logistic regression) model, using historical flooding records from the Maldives following the 2004 Indian Ocean Tsunami. The data with respect to the geological and geomorphological parameters of the islands and reefs, which were collected from 202 inhabited islands and seven resorts in the Maldives, were weighted by the presence/absence of evidence from the impacted islands. The tsunami hazard and risk were evaluated using spatial weights calculated for each variable. The predicted tsunami risk was compared with the impact of the 2004 Indian Ocean Tsunami. The results show that for the three cases, the success rate of the estimated hazard and risk prediction ranged between 74% and 90% for the low and high impact islands, respectively. However, the predictability for medium impact islands in the three cases was within the range ...
The 2004 Indian Ocean tsunami was one of the most devastating tsunamis in world history. The tsun... more The 2004 Indian Ocean tsunami was one of the most devastating tsunamis in world history. The tsunami caused damage to most of the Asian and other countries bordering the Indian Ocean. After a decade, reconstruction has been completed with different levels of tsunami countermeasures in most areas; however, some land use planning using probabilistic tsunami hazard maps and vulnerabilities should be addressed to prepare for future tsunamis. Examples of early-stage reconstruction are herein provided alongside a summary of some of the major tsunamis that have occurred since 2004, revealing the tsunami countermeasures established during the reconstruction period. Our primary objective is to report on and discuss the vulnerabilities found during our field visits to the tsunami-affected countries-namely, Indonesia, Sri Lanka, Thailand and the Maldives. For each country, future challenges based on current tsunami countermeasures, such as land use planning, warning systems, evacuation facilities, disaster education and disaster monuments are explained. The problem of traffic jams during tsunami evacuations, especially in well-known tourist areas, was found to be the most common problem faced by all of the countries. The readiness of tsunami warning systems differed across the countries studied. These systems are generally sufficient on a national level, but local hazards require greater study. Disaster reduction education that would help to maintain high tsunami awareness is well established in most countries. Some geological evidence is well preserved even after a decade. Conversely, the maintenance of monuments to the 2004 tsunami appears to be a serious problem. Finally, the reconstruction progress was evaluated based on the experiences of disaster reconstruction in Japan. All vulnerabilities discussed here should be addressed to create longterm, disaster-resilient communities.
This study deals with the "safer island concept" implemented for the re... more This study deals with the "safer island concept" implemented for the reconstruction and rehabilitation works after the 26 December 2004 Indian Ocean Tsunami in the Maldives. The safer island concept has been developed as an important adaptation strategy for tsunamis as well as the sea-level rise due to climate change. Reconstruction work in Dhuvaafaru Island to rehabilitate the entire population of Kandholhudhoo Island of Raa atoll is chosen as a case study. The appropriateness of the functionality of the redesigned island to provide security and safety for the island communities is evaluated using the digital elevation model. The study results show that the design enhanced mitigation measures of the island might show some resilience for less frequent natural disasters such as smaller tsunamis, while the implementation of the concept may create greater vulnerability for more frequent disasters, such as flash floods and storms. An integrated approach with appropriate risk assessment of floods, storms, and other physical aspects of the island is recommended for the future development of the safer island concept.
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