No abstract

The challenge of protecting communities in tsunami-prone populated small islands is difficult to meet. Likewise, the islands are often found with a lack of disaster mitigation infrastructure. A tsunami that occurred around the Mentawai Islands of Indonesia on October 25, 2010, causing around 500 dead, is the inspiration for this paper. This study was aimed at elaborating practices in protecting communities of small islands from tsunamis by incorporating information about the estimated time of arrival of a tsunami into the islands mitigation measures. A field survey to obtain the impacts of the tsunami on the number of casualties and damages was conducted in February 2011 around the Mentawai Islands. In the survey, a set of questionnaires were distributed in the Mentawai Islands to investigate the small island residents' responses just after the shock from the tsunami waves. This study was also followed by numerical simulations to obtain tsunami wave Estimated Time of Arrival (ETA) for the Mentawai islands. Numerical simulations were conducted using Delft3D software coupled with Tsunami toolkit. This research found that the ETAs for the Mentawai Islands range between 9–20 min. With the existing tsunami early warning system in Indonesia, the ETAs are quite short. Comparing the Simulated ETAs to the findings from the Mentawai Islands tsunami survey led to the recommendation that the best way to increase the community's preparedness for a tsunami would be by managing village-based spatial planning. Such spatial planning may include relocating the residents far away from the coastal area. This would enable the community to have more time to evacuate should a tsunami threat occur.

Since 2014 sedimentation at the estuary of Jelitik river, Sungailiat, Bangka has continued to increase. At this estuary, the ship traffic is very busy and there is National Fisheries Port Sungailiat. When the tide is low, the river mouth closes thus disrupting ship traffic. The Bangka Belitung Provincial Government is currently planning to build a sediment control infrastructure to reduce the sedimentation rate. To plan and determine the effectiveness of the jetties requires knowledge of sedimentation patterns around Jelitik estuary. Therefore this study was conducted to determine the pattern of sedimentation (distribution and rate) at the existing and ultimate conditions. The methods are field survey, analysis of field data, and computational modeling of sediment transport. Modeling of sediment transport was done using the Sand Transport Module of MIKE 21. Two scenarios were simulated for the existing and ultimate conditions. Based on this modeling, the sedimentation rate at Jelitik estuary is found uneven. In the existing condition, a large rate of sedimentation occurs on the southern side of the Jelitik River estuary, which reaches a maximum value of 2.75 m/year, with an average of 4.44 cm/year. Whereas in the ultimate condition, the sedimentation rate decreases to 0.0377 m/year.

No abstract

BPPT-lock was developed by the Agency for The Assessment and Application of Technology (BPPT) and was awarded patent in 2012. The hydraulic stability (KD) of BPPT-lock armor unit was compared to Tetrapod, Dolos and Xbloc armor units. The results indicate that, BPPT-lock performs far better KD in comparison to each of these armor units. A comparative analysis on the economical use of material was also carried out among BPPT-lock, Dolos, Tetrapod and rough stone and rounded stones for similar design condition, the armor unit weight is 4.68ton, 4.97ton, 9.95ton, 19.89ton, and 39.79ton respectively, means that BPPT-lock is more efficient in this comparison. Considering its feasible performance, BPPT-lock is designed as the armor units for the maintenance and reparation of the existing rubble mound breakwater of Pacitan Coal Fired Power Plant port. The 110 m parts of the existing breakwater was hardly damaged and the new structure is designed to stand against a 30 yrs RP waves of Hs = 7m. BPPT-lock armor unit of W = 11 ton on the breakwater slope 1:1,5 is implemented. The first phase construction works was completed in December 2018 and visual observation has shown the great integrity and stability of BPPT-lock armor units.