Towards Comprehensive Tsunami Mitigation Study: a Case of Legundi Island

Sunda Strait Tsunami happened in December 2018 due to a flank collapsed of Mount of Anak Krakatoa. Lampung Province was affected by Sunda Strait Tsunami at various locations that close to Mount of Anak Krakatoa. The research is conducted to modelling the tsunami wave that happened at Legundi Island in 1D model using SwanOne software. The methodology of the research is using data input from bathymetric survey and apply the wave transformation equations in the nearshore using SwanOne software to do the 1D model. There are four scenarios to do the wave modelling. All scenarios consider from former study about Sunda Strait Tsunami 2018. The results from all scenarios are verified by prior research from Takabatake (2019) of inundation height in Legundi Island, it is 3,34 m. The result shows the inundation height from wave modelling is a combination of wave height (1,533 m), water depth (1,658 m) and wave setup (0,215 m), and the outcome is 3,406 m. The model shows a fine result because the percentage error of the model is only 0,769%, which is below 5%. This research can be a good approach for another wave modelling in other locations and also to do further research to wave modelling in 2D model

Efektifitas Pemecah Gelombang Tiang Pancang Bambu Bulat Bersekat

Salah satu permasalahan yang terjadi di wilayah pantai adalah erosi pantai. Erosi ini apabila terjadi terus menerus dapat mendatangkan permasalahan yang cukup serius terutama pada pantai berlumpur. Umumnya, kerusakan ini disebabkan oleh beberapa faktor dan salah satu yang sangat mempengaruhi pada jenis pantai ini adalah gelombang yang berasal dari lepas pantai. Untuk melindungi pantai berlumpur dari kerusakan akibat gelombang, diperlukan perlindungan pantai dengan tipe pemecah gelombang permeable. Jenis permeable ini salah satunya adalah pemecah gelombang tiang pancang dengan bahan bamboo bulat bersekat. Untuk mencapai optimasi dalam penggunaannya, maka diperlukan analisis refleksi dan transmisi terhadap hasil pengujian model fisik 2D terhadap pemecah gelombang ini dengan menghitung nilai koefisien refleksi dan koefisien transmisinya. Dari penelitian ini diketahui bahwa secara umum  memiliki hubungan berbanding terbalik terhadap nilai dan sedangkan  memiliki hubungan berbanding lurus terhadap nilai dan . Tinggi muka air yang paling efektif untuk pemecah gelombang ini adalah MSL atau muka air rendah daripada pada saat HWL. Skenario spasi yang paling efektif adalah skenario dengan spasi antar tiang = 1 cm

ANALISIS REFLEKSI DAN TRANSMISI GELOMBANG PADA PEMECAH GELOMBANG TIANG PANCANG

The muddy beach vulnerable to wave damage, coastal protection is needed by using permeable breakwaters type. Permeable breakwaters are being developed, namely with Pile Breakwater. The material used for the protoype in laboratory is rounded insulated bamboo, which is round bamboo from Pringgodani garden with a diameter of 1 cm, height of 20 cm with a multiblock wooden bulkhead with thick of 2 cm. Reflection and transmission analysis on the results of 2D physical modelling of the breakwater is needed to achieve optimization in its use. Breakwater is effective in scenarios that have smaller Kt  values and larger Kr  values. In this study the test was carried out with water level at Mean Sea Level (MSL) (44 cm) and High Water Level (HWL) (50 cm) with 2 spatial scenarios between 1 cm and 2 cm. Then the calculation results of Kt  and Kr are compared with nondimensional wave steepness variables (Hi/gT2 ) and wave slope (Hi/L)). From this laboratory study, it is shown that  has lower values at MSL and  has higher values at MSL. This fact shows that the permeable breakwater with bamboo more effective at low water level than at high water level.Pantai berlumpur rentan terhadap kerusakan akibat gelombang, sehingga diperlukan perlindungan pantai yang salah satunya menggunakan pemecah gelombang tipe permeable. Tipe permeable yang dikembangkan ini disebut sebagai Pemecah Gelombang Tiang Pancang. Bahan yang digunakan untuk memodelkan struktur tersebut (prototipe) di laboratorium adalah bambu bulat bersekat yaitu bambu bulat dari taman Pringgodani dengan diameter 1 cm, tinggi 20 cm dengan sekat kayu multiblok setebal 2 cm. Analisis refleksi dan transmisi terhadap hasil pengujian model fisik 2D terhadap pemecah gelombang diperlukan untuk mencapai optimasi dalam penggunaannya. Hasil pengujian laboratorium membuktikan bahwa Pemecah Gelombang ini cukup efektif pada skenario yang memiliki nilai Kt yang lebih kecil dan nilai Kr yang lebih besar. Pada percobaan ini pengujian dilakukan dengan skenario tinggi muka air pada Mean Sea Level (MSL) (44 cm) dan High Water Level (HWL) (50 cm) dengan 2 skenario spasi antar tiang yaitu 1 cm dan 2 cm pada masing-masing tinggi muka air. Kemudian hasil perhitungan Kt dan Kr dibandingkan dengan variabel non-dimensional kecuraman gelombang (Hi/gT2) dan kemiringan gelombang (Hi/L) . Hasil percobaan laboratorium menunjukkan bahwa nilai Kt lebih rendah pada saat kondisi MSL, dan nilai Kr lebih tinggi pada saat kondisi MSL hal ini menunjukkan bahwa Pemecah Gelombang Bambu Bulat Bersekat ini lebih efektif pada muka air rendah dari pada muka air tinggi

Analisis Regresi Pada Tren Perubahan Garis Pantai di Pantai Krui dari Digitasi Citra Landsat

Krui is a capital of Pesisir Barat Regency of Lampung Province which has important values on residential areas, business centers, government centers, and tourism destination. Kruis coast is adjacent to the Indian Ocean, which has the high wave characteristic cause the dynamic coastal process similarly to other sandy beaches on the west coast of Sumatera Island. The coastal process can be shown in the form of either coastline accretion due to sedimentation or shoreline reduction caused by the phenomenon of erosion and abrasion. The coastal process can be observed as a natural process to achieve an equilibrium of sediment transport along the coast. Also, Shoreline change is influenced by the height waves and the direction of incoming waves towards onshore depending on the season. The aims of this study is to get an overview of the shoreline changes that occur on the Krui Coast. Then it can be predicted the position of the coastline in the future. The regression model was chosen to estimate the position of shoreline in the future by utilizing a set of time-series data that refers to shoreline change within certain periods. Digitized Landsat-7 ETM+ satellite imagery is conducted in order to obtain shoreline position data in every year determinate as historical data. Based on this study, the rate of shoreline change in Krui Coast is within range of 0,12 meters/year to 41,35 meters/year, where is the shoreline change tends to increase. Keywords: Digitization, Landsat, Shoreline, Regressio

Field Survey of Flank Collapse and Run-up Heights due to 2018 Anak Krakatau Tsunami

Dataset: https://data.4tu.nl/articles/dataset/Bathymetry_data_underlying_the_publication_Field_survey_of_flank_collapse_and_run-up_heights_due_to_the_2018_Anak_Krakatau_Tsunami/1421561

Application MuTsunami in Mentawai Island Indonesia

Software MuTsunami as research tool in Coastal Research Group Institut Teknologi Bandung, was applied to simulate propagation of tsunami and sediment transport in Mentawai. The Tsunami occurred in 25 October 2010, 21:42:22 (GMT +7). The hydrodynamic model was based on Non-Orthogonal curvilinear coordinate in spherical coordinate. The results of simulation were compared with observational data, which was collected by group of researcher from Institut Teknologi Bandung, Waseda University, and Yokohama National University. The agreement between the model and observational data are very good

Application MuTsunami in Mentawai Island Indonesia

Software MuTsunami as research tool in Coastal Research Group Institut Teknologi Bandung, was applied to simulate propagation of tsunami and sediment transport in Mentawai. The Tsunami occurred in 25 October 2010, 21:42:22 (GMT +7). The hydrodynamic model was based on Non-Orthogonal curvilinear coordinate in spherical coordinate. The results of simulation were compared with observational data, which was collected by group of researcher from Institut Teknologi Bandung, Waseda University, and Yokohama National University. The agreement between the model and observational data are very good

Towards Comprehensive Tsunami Mitigation Study: A Case of Legundi Island

Sunda Strait Tsunami happened in December 2018 due to a flank collapsed of Mount of Anak Krakatoa. Lampung Province was affected by Sunda Strait Tsunami at various locations that close to Mount of Anak Krakatoa. The research is conducted to modelling the tsunami wave that happened at Legundi Island in 1D model using SwanOne software. The methodology of the research is using data input from bathymetric survey and apply the wave transformation equations in the nearshore using SwanOne software to do the 1D model. There are four scenarios to do the wave modelling. All scenarios consider from former study about Sunda Strait Tsunami 2018. The results from all scenarios are verified by prior research from Takabatake (2019) of inundation height in Legundi Island, it is 3,34 m. The result shows the inundation height from wave modelling is a combination of wave height (1,533 m), water depth (1,658 m) and wave setup (0,215 m), and the outcome is 3,406 m. The model shows a fine result because the percentage error of the model is only 0,769%, which is below 5%. This research can be a good approach for another wave modelling in other locations and also to do further research to wave modelling in 2D model