Search

Aliran yang disebabkan oleh kegagalan bendungan memiliki potensi untuk menyebabkan terjadinya suatu bencana. Oleh sebab itu, aliran ini sering dikaji baik secara uji dilaboratorium ataupun simulasi numerik untuk mengetahui secara rinci proses terjadinya penjalaran aliran tersebut. Sehingga, hasil penelitian tersebut dapat diaplikasikan untuk mengurangi dampak yang dapat disebabkan oleh aliran tersebut. Saat ini aliran oleh kegagalan bendungan tidak hanya digunakan untuk mengkaji dampak dari kegagalan bendungan akan tetapi digunakan juga untuk mengkaji aliran gelombanmg tsunami. Penelitian ini bertujuan untuk mengevaluasi kemampuan model DualSPHysics dalam mensimulasi aliran yang disebabkan oleh kegagalan bendungan. Aliran dibangkitkan dengan dua cara, yaitu melepaskan air secara tiba-tiba (tanpa pergerakan pintu) dan mensimulasikan pergerakan dari pintu yang digeser kearah atas mengikuti proses pembangkitan yang telah dilakukan dilaboratorium. Proses validasi dilakukan dengan membandingkan fluktuasi muka air dan kecepatan aliran antara data hasil uji laboratorium yang telah dikeluarkan dan simulasi numerik menggunakan DualSPHysics. Hasil simulasi menunjukkan bahwa program DualSPHysics dapat mensimulasikan proses penjalaran aliran oleh kegagalan bendungan dengan baik. Model ini direkomendasikan untuk dapat diaplikasikan dalam mensimulasikan aliran yang disebabkan kegagalan bendungan pada kondisi nyata dengan daerah simulasi yang lebih luas.

There are numerous small populated islands near western Sumatra in Indonesia. The Weh, Banyak, Mentawai, and Enggano islands are home to many Indonesians. These small islands have been found to be effective at reducing tsunami wave energy on several occasions. At the same time, they are situated around Sumatras active subduction zone and are often among the areas most affected by tsunamisas in the case of Pulo Raya Island, in the western Aceh Jaya district about 800 m from Sumatra. Pulo Raya was devastated by the 2004 Indian Ocean tsunami. This study investigates the hydrodynamic processes of reflected tsunami waves and their impact on Pulo Raya, using a Cornell Multi-grid COupled Tsunami (COMCOT) model to simulate the tsunami wave runup and subsequent hydrodynamic processes. The simulation confirms eyewitness accounts that it was not the initial runup, but the reflected waves that devastated the worst-hit areas of the island. As a result, we can recommend that governments and communities on small islands need to anticipate the impacts of reflected waves following a tsunami, especially at lee side of of the island that was perceived to be a safer place by the island community before the 2004 Indian Ocean tsunami.

Fifteen years since the 2004 Indian Ocean tsunami, which caused massive destruction around the Andaman Sea, people have participated in efforts to reduce tsunami risks in Indonesia. However, the most important question continues to be on whether such efforts are sufficient in dealing with tsunami risks. Among the most striking challenges here is bridging the gap in tsunami risk reduction between the Sumatra mainland and among communities in several small islands. Thus, this research aims to investigate the recent conditions of selected towns/cities in tsunami-prone small islands and identify the impediments to their tsunami hazard preparedness. It focuses on comparing efforts in terms of available facilities for tsunami evacuation plans and the tsunami estimated time of arrival (ETA), which is computed based on deterministic tsunami propagation models. In this regard, five of the observed locations are classified as being in a critical tsunami preparedness condition, namely Balai island, Lahewa of Nias Island, Sabeugunggung of North pagai Island, Surat Aban of South Pagai island, and Enggano Island. Most of them have limited space for tsunami evacuation and a short tsunami ETA, which constitutes an extreme condition requiring immediate tsunami mitigation measures. One possible approach is to construct a vertical tsunami evacuation building or modify existing buildings that can be used for tsunami evacuation on the islands. This article also highlights societal aspects related to tsunami preparedness.

Ten years after the Indian Ocean Tsunami of 2004, the Aceh Province in Indonesia has made progress toward becoming a more tsunami resilient area. The government of Indonesia has undertaken a number of efforts to facilitate a better evacuation process, but a smooth evacuation process is still at large. A major issue is that the disaster management office for the districts are yet to have clear, accurate estimations of what would be the shortest time of the arrival of the tsunami waves.The worst scenario for these cities' tsunami evacuation procedures has yet to be determined. This study seeks to discern worst tsunami estimated times of arrival for the tsunami-prone cities in Aceh. A number of numerical simulations were performed using data from past events of tsunamis in this area and a future near-shore tsunami events anticipated by most of the disaster managers around the Mentawai Island. The Cornell Multi-grid COupled Tsunami (COMCOT) model was used as the tool for the simulations. Nine selected cities were determined as observation points, i.e., Sabang, Banda Aceh, Calang, Lageun, Teunom, Meulaboh, Singkil, Sinabang, and Tapaktuan. The results of this research show that the shortest ETAs are Banda Aceh 35 min, Sabang 22 min, Lageun 25 min, Calang 29 min, Teunom 29 min, Meulaboh 35 min, Sinabang 20 min, Singkil 53 min, and Tapaktuan 24 min.

Numerical simulation is one of the useful tools to analyze natural phenomena in the earth such as the tsunami disaster. Several numerical models can simulate the tsunami wave from its generation, propagation, and inundation. However, most tsunami models do not include the sediment transport module. The tsunami wave actually induces a lot of sediment during the propagation in the coastal area. In the case of Indian Ocean Tsunami in 2004, massive morphological changes were caused by the tsunami waves around Sumatra coast. In Aceh, some areas eroded by the tsunami wave were living place for a local community. It is indispensable for the resident in the coastal area to estimate the risk of morphological changes due to a tsunami wave. Therefore, a model that can investigate the morphological changes due tsunami wave is necessary. The result of this model can be used to consider a countermeasure for tsunami wave impact in the coastal area, such as land-use management and planning. The COMCOT-SED model had been developed by several researchers. This model combines the hydrodynamic module and the sediment module. The aim of this study is to get general information about performance of the COMCOT-SED model and to modify the model for more accurate results. Firstly, the model was demonstrated in the ideal condition to confirm the model validity. Then, we evaluated the model performance comparing the model results and the laboratory experiment data which was conducted by other researcher. The authors found that the results of water level and bottom profile by the original model in the ideal condition are not suitable. The model modification will give us more suitable results. The modified model will be applied to simulate the tsunami wave and sediment transport in the small area.

Coastal recovery at tsunami affected areas is another challenging work for practitioners. Pressures from demand to acquire ample and suitable land to restart economy activities and from harmonizing nature with the development are among the reasons why the coastal recovery may enter into complicated decision process. This chapter elaborates lessons learned from coastal recovery process around Banda Aceh to restore coastal lines around this area after severely damaged by the Indian Ocean Tsunami waves in 2004. A time series of maps to show the coastal morphological dynamics around Banda Aceh was used to compare the coastal features between 2004 and 2011 conditions. Other similar studies focusing on the coastal recovery around this area were also included to strengthen the lessons of the coastal recovery process orchestrated after the tsunami. Four coastal locations around Banda Aceh were selected to show the different approaches used to recover the coasts and impacts on the area after the efforts.