ANALISIS HIDRODINAMIKA PADA PERENCANAAN JETTY SIANTAN SELATAN, KEPULAUAN ANAMBAS

ANALISIS HIDRODINAMIKA PADA PERENCANAAN JETTY  SIANTAN SELATAN, KEPULAUAN ANAMBAS

Prelimenary Modeling for Assessing Tidal Stream Energy Potential at the Alas Strait, Indonesia

This study is on ocean current prelimenary modelling in Alas Strait, Indonesia, to be compared with the field observation data. The model maps coordinate for ocean current so that the potential energy resource can be identified. The model simulation is established with two different scenarios; the first scenario is using windspeed factor and the second without using that factor. Complementary variables such as bathymetry, water elevation, bottom friction, and eddy viscosity have the same value for both scenarios. This ocean current modelling use finite element method with flexible mesh. This method use two dimension numerical solution from the average incompressible Reynolds Navier – Stokes equation with the assumption from Boussinesq dan hydrostatic pressure. This model consists of continuity equation and momentum which closed by turbulen scheme. This study concludes the first scenario is a success and valid with the water surface elevation mean error is 4.2% and water current speed mean error is 10.7%. The second scenario is unseccesful as indicated by the water surface elevation mean error of 13.4% and the water current speed mean error of 11,7%, and also the phase and the trend of current speed is verging the field observation data

The Analysis of Wafe Refraction using SWAN Model

Wave simulation is important problem in nearshore coastal design process. Determination of proper wave parameter will provide reliable and accurate design, therefore modeling usually needed to simulate this process where numerical model is the right choice because of its cost is cheaper and the result is quite accurate. SWAN (Simulating Wave Nearshore) is numerical model that already used widely to simulate wave in coastal area. In this research we analyze wave refraction by SWAN model with any coastal profile (m) i.e. 0,01 , 0,03 and 0,05. This simulation also applied in the real problem at Tegal port in Central Java Province. According to the result of this model we find that in the same direction, height, and period, the height of wave break will increase as the coastal slope increase. These problems arise due to decreasing in value of db/Hb that means the peak wave is become steep. Coastal Profile affect the wave height (duo to refraction) about 2%-34%. The jetty at Tegal Port induce the wave height big alteration at dock pond (228,91%) at wave direction 30o, while at groove, back and head of the jetty, wave reduction reach until 12,96% ; 0,02% and 3,55% at incoming wave direction 45o. In the head of the jetty, the wave almost doesn’t being reduced because diffraction and wave reflection doesn’t have significant effect

Wave Transmission Analysis on Hexagonal Shape Floating Breakwater

Coastal areas have many benefits for activities, such as port construction, fishing activities, recreation areas, resource utilization, alternative energy-producing places, etc. However, many factors limit this use due to water wave activity, such as storm surges and the potential for tsunamis. These factors also cause abrasion and coastal erosion that can damage the coastal environment. To overcome this problem, it can be done by building a coastal protective structure, one of which is a floating breakwater. In this study, analysis of wave transmission on a hexagonal floating breakwater will be carried out to determine the effectiveness of its performance. The wave transmission test on the floating breakwater was carried out with variations of irregular waves (Jonswap spectrum) and mooring angles. The position of the wave probe is set at 100 cm and 220 cm behind the structure. The largest transmission coefficient occurs at a mooring angle of 30o in both scenario 1 and scenario 2. The smallest transmission coefficient value is at an angle of 60o in both scenarios of wave probe placement. The plotting results show that the transmission coefficient is directly proportional to the period and height of the incident wave and vice versa the transmission coefficient is inversely proportional to the steepness of the wav

A Study on the Reservoir Capacity to Control Mud Flood Derived from Mud Volcano: A Phenomenon in Sidoarjo

This paper is an extended research of Coastal Zone Management of Sidoarjo mud phenomenon. The idea is to find special concept of management to control mud flood using reservoir system. This method, in the mud fluid, is intentionally used to make separation of the solid materials from water. The concept is to calculate sediment velocity in order to find the time of sedimentation then to estimate the volume of mud. Therefore, the reservoir will be determined from this calculation. The result of this research is the dimension of the reservoir: area of 3,704,144.36 m2, the depth of 5.94 m, and the volume 22.018.856.07 m3. The time of sedimentation is calculated of 28.33 hours for 42.2 % of material volume sedimentation. Consequently, the suspension material is 57.8 %. The correction of calculation is depending on the calculation of the velocity of sedimentation, about 2 %

Pemodelan Penjalaran Tsunami Akibat Erupsi Gunung Anak Krakatau Beserta Skenario Dike, Studi Kasus Teluk Jakarta

Gunung Anak Krakatau merupakan gunung api aktif di Indonesia. Gunung Anak Krakatau terus memperlihatkan aktifitas vulkanik, hal ini dibuktikan oleh tsunami pada 22 Desember 2018 yang di akibatkan oleh erupsi Gunung Anak Krakatau. Jakarta sebagai ibukota negara dan memiliki jumlah penduduk terpadat di Indonesia sudah sewajarnya memiliki rencana mitigasi dini untuk mengurangi dampak dari bencana tsunami. Sejalan dengan usaha mitigasi tersebut, Pemda DKI Jakarta mengemukakan rencana tata ruang wilayah Jakarta tahun 2030 yang dikenal sebagai Master Plan NCICD (National Capital Integrated Coastal Development). Panduan Master Plan NCICD memiliki proyek utama dalam pengembangan pesisir Teluk Jakarta yaitu dengan pembangunan tanggul laut. Akan tetapi menurut penelitian sebelumnya, desain tanggul laut Master Plan NCICD yang berbentuk garuda dinilai kurang efektif dalam segi hydraulic. Penelitian ini bertujuan untuk memodelkan penjalaran tsunami yang disebabkan oleh erupsi Gunung Anak Krakatau ke Teluk Jakarta. Selain itu, penelitian dilanjutkan dengan memodelkan skenario jamak tsunami dike sebagai upaya dalam mereduksi ketinggian tsunami yang sampai ke Teluk Jakarta. Adapun kondisi awal kenaikan muka air laut merujuk pada tsunami akibat erupsi Gunung Krakatau tahun 1883. Pemodelan tsunami dilakukan dengan bantuan software MIKE 21. Hasil dari penelitian ini menunjukkan penjalaran tsunami selama 6 jam, dan diperoleh ketinggian elevasi muka air 1.437 meter pada titik validasi. Sedangkan tinggi elevasi muka air dari data validasi adalah 1.451 meter. Pemodelan dengan skenario dike dapat mengurangi tinggi elevasi muka air di dalam area dike masing – masing adalah 100% untuk skenario dike 1 (tipe dike tertutup), 99.58% untuk skenario dike 2 (tipe dike semi tertutup dengan 1 gap), 86.26% untuk skenario dike 3 (tipe dike terbuka dengan 11 gap)

MODEL NUMERIK PENGARUH ARTIFICIAL REEF DALAM REDUKSI GELOMBANG DAN PERUBAHAN MORFOLOGI PANTAI MENGGUNAKAN DELFT3D

MODEL NUMERIK PENGARUH ARTIFICIAL REEF DALAM REDUKSI GELOMBANG DAN PERUBAHAN MORFOLOGI PANTAI MENGGUNAKAN DELFT3

Numerical Modeling of Hydrodynamic Performance on Porous Slope Type Floating Breakwater

A floating breakwater is a coastal building that aims to break up or withstand wave energy that enters the beach so that the characteristics of the incoming waves are by calculations and can reduce abrasion on the shoreline. Designing a floating breakwater is very complicated because it depends on many aspects. These fundamental aspects depend on each other, so if one of these aspects changes, the integrity of the floating breakwater structure will also change. One of these aspects is the magnitude of the transmission and reflection coefficients generated by the floating breakwater. This research will study the hydrodynamic performance of floating breakwater due to variations in slope and porosity in reducing and reflecting waves with computational fluid dynamics (CFD). The slope-porous floating breakwater dimension is based on previous experimental data, including a constant water depth of 0.75 m, a wave height of 0.05 - 0.125 m, and a wave period of 1.1 - 2 sec on regular waves. The results of the numerical model validation and experiments on all variations of the floating breakwater model are quite good, which is less than 10% for both wave transmission and reflection. Analysis of the influence of changes in the mooring line angle, the simulation is carried out at an angle of 30 deg to 90 deg and produces an average transmission coefficient of 0.79 and a reflection of 0.21. While the effect of changes in water level elevation (0.85 m, 0.75 m, and 0.65 m) gives a reasonably significant average transmission coefficient of 0.85 and a reflection of 0.13. The mooring line angle will be gentler at high tide, and the transmission and reflection coefficients will be higher. However, the mooring line will loosen at low tide, causing the structure to move more freely and eliminating the function of the floating breakwater itself so that the tidal phenomenon becomes a challenge for coastal experts in designing structures to produce effective and efficient hydrodynamic performance