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Wave Spectrum Change in The Vicinity of Artificial Reef Armono, Haryo D; Kurniawan, Andi; Akhwady, Rudhy; _, Sujantoko
Journal of Indonesian Coral Reefs Vol 1, No 2 (2011)
Publisher : Journal of Indonesian Coral Reefs

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Artificial reefs have capability to enhance the environment, improve aesthetics and provide protection needed in certain coastal areas. The perforated hollow cylindrical shape artificial reefs are proposed as submerged breakwater due to characteristics that are not found in conventional breakwaters such as the water circulation and fish habitat enhancement capability. As submerged breakwater, the performance of artificial reefs are displayed by their capabilities in reducing wave energy. The change of wave energy spectrum in the vicinity of perforated hollow cylindrical shape artificial reefs is presented in this paper. The influence of wave steepness, relative reef height and relative reef width to the spectrum wave transmission were studied by physical model. The change of the wave spectrum were observed by comparing the area of the incoming wave spectrum to the transmitted wave spectrum. It is shown that the energy of incoming wave were reduced significantly by artificial reefs, providing the quiescent area in the shoreline.

Model Simulasi Interaksi Gelombang dan Arus di Perairan Dangkal Sujantoko, Sujantoko; Natakusumah, Dantje Kardana
Jurnal Teknik Sipil Vol 10, No 3 (2003)
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (466.041 KB)

Abstrak. Persamaan mild-slope yang diturunkan Kirby (1986) dapat diterapkan untuk simulasi transformasi gelombang dari perairan dalam menuju pantai. Pada paper ini dikembangkan model Kirby dengan memperhatikan factor arus. Pengaruh arus pada transformasi gelombang tersebut diselesaikan dengan metode selisih hingga. Berdasarkan verifikasi model numerik dengan analitik menunjukkan bahwa perbedaan kecepatan rata-rata arus longhsore kurang dari 5%, artinya model numerik ini dapat mensimulasikan arus akibat induksi gelombang dengan baik. Verifikasi model gelombang dengan hasil penelitian Johnson (1952), Wiegel (1962) dan Wei (1998) menunjukkan adanya kemiripan, sedangkan perbedaan yang ada karena pada model mempertimbangkanfaktor arus.Abstract. Mild-slope equations have been derived by Kirby (1986) can be applied on simulation of wave transformation from deep water to coastal. This paperâs developed Kirbyâs model with considering current factor. The effect of current on wave transformation have been modeled with finite difference methods. According to verification of numerical models and analytical model, the difference of mean longshore current velocity less than 5%, it means that this numerical modelÂ provide good simulation of current caused by wave induction. Verification of wave model on Johnson (1952), Wiegel (1962) and Wei (1998) result similarity, but thereâs still any difference thismodel considering current factor.Abstrak. Persamaan mild-slope yang diturunkan Kirby (1986) dapat diterapkan untuk simulasi transformasi gelombang dari perairan dalam menuju pantai. Pada paper ini dikembangkan model Kirby dengan memperhatikan factor arus. Pengaruh arus pada transformasi gelombang tersebut diselesaikan dengan metode selisih hingga.Berdasarkan verifikasi model numerik dengan analitik menunjukkan bahwa perbedaan kecepatan rata-rata aruslonghsore kurang dari 5%, artinya model numerik ini dapat mensimulasikan arus akibat induksi gelombangdengan baik. Verifikasi model gelombang dengan hasil penelitian Johnson (1952), Wiegel (1962) dan Wei(1998) menunjukkan adanya kemiripan, sedangkan perbedaan yang ada karena pada model mempertimbangkanfaktor arus.Â Abstract. Mild-slope equations have been derived by Kirby (1986) can be applied on simulation of wave transformation from deep water to coastal. This paperâs developed Kirbyâs model with considering current factor. The effect of current on wave transformation have been modeled with finite difference methods. According to verification of numerical models and analytical model, the difference of mean longshore current velocity less than 5%, it means that this numerical model provide good simulation of current caused by wave induction. Verification of wave model on Johnson (1952), Wiegel (1962) and Wei (1998) result similarity, but thereâs still any difference thismodel considering current factor.

Model Gelombang di sekitar Hexagonal Artificial Reef sebagai Submerged Breakwater Menggunakan DUALSPHYSICS Armono, Haryo Dwito; Manurung, Adelbert; Sujantoko, Sujantoko
Rekayasa Vol 15, No 1: April 2022
Publisher : Universitas Trunojoyo Madura

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21107/rekayasa.v15i1.13484

The functions and uses of artificial reef have evolved from a method of coral reefs restoration to a coastal protection system. Artificial reef can reduce the hydraulic load on the coast to the level required to maintain shoreline balance. Various materials and shape of artificial reefs have been introduced. This paper discussed the wave transmission over hexagonal-shaped artificial reef with 6 holes on each side. The study was conducted using the Smoothed Particle Hydrodynamic (SPH) method integrated in DualSPHysics software to see the effect of gaps between structures with a predetermined configuration to the value of the transmission coefficient (Kt). It was found that the configuration with no gap was able to absorb waves better than the configuration with a gap of 0.15 m and 0.112 m based on the Kt value obtained. In terms of hydrodynamics, it was found that: (1) The increment of the wave steepness, the smaller the Kt value obtained, (2) The larger the wave height, the smaller the Kt value at 0.1 m freeboard depth, while on the freeboard with a depth of 0.2 m and 0.3 m, it was found that the greater the wave height, the greater the Kt value, (3) the increment of the wave period, the Kt were higher, and also (4) the higher the freeboard, the higher the Kt.

STUDI KARAKTERISKTIK GELOMBANG PADA FLOATING BREAKWATER TIPE TERPANCANG DAN TAMBAT Sujantoko Sujantoko; Wisnu Wardhana; Eko Budi Djatmiko; Haryo Dwito Armono; Wahyu Suryo Putro; Rizki Haryono A.
JURNAL TEKNIK HIDRAULIK Vol 12, No 1 (2021): JURNAL TEKNIK HIDRAULIK
Publisher : Pusat Litbang Sumber Daya Air, Kementerian Pekerjaan Umum dan Perumahan Rakyat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32679/jth.v12i1.650

Floating breakwater (PGT) is designed to be applied as a wave barrier to reduce beach abrasion and wave energy so that waves coming to the beach have their energy reduced. Compared to conventional breakwater structures, PGT structures are more advantageous if the area to be protected from impact waves has a large enough depth. This structure is more flexible because the elevation follows the tides, so this structure can be used as a wharf at the same time. It is also free from the scouring and sedimentation that often occurs on the feet of conventional breakwater structures. This study aims to attenuate and reflect waves from various PGT configurations of piling and mooring types, by testing the physical model of PGT in the wave flume laboratory of the Department of Ocean Engineering ITS, at a water depth of 80 cm, a wave height of 3.5-5.5 cm, a wave period of 0.5-2 seconds, and the angle of the mooring rope (45o, 60o, 90o). PGT is arranged in a variety of longitudinal and transverse directions to the coast. Based on the experiment, it is known that the effect of configuration and width on the PGT structure on wave transmission and reflection is influenced by the mooring angle. Configuration 3 with the largest width can give the best transmission coefficient Kt = 0.797 at 45o mooring angle and reflection coefficient Kr = 0.572 at 90o mooring angle. In type 3 fixed-configuration gives the greatest value Kt = 0.431-0.623 and Kr = 0.053-0.997 compared to other configurations. Because in configurations 1 and 2 the back of the structure is not supported by piles, so a swing occurs which generates waves. While the effect of the slope of the wave, Kt will increase as the number of waves slopes decreases, conversely the value of Kt decreases with the increase in the slope of the wave.Keywords: Floating breakwater, piling, tethered, mooring

Pemodelan Penjalaran Tsunami Akibat Erupsi Gunung Anak Krakatau Beserta Skenario Dike, Studi Kasus Teluk Jakarta Nur Chasanah; Haryo Dwito Armono; Sujantoko Sujantoko; Juventus Welly Radianta Ginting
Jurnal Teknik ITS Vol 9, No 1 (2020)
Publisher : Direktorat Riset dan Pengabdian Masyarakat (DRPM), ITS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j23373539.v9i1.50609

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 Simulasi Interaksi Gelombang dan Arus di Perairan Dangkal Sujantoko Sujantoko; Dantje Kardana Natakusumah
Jurnal Teknik Sipil Vol 10 No 3 (2003)
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/jts.2003.10.3.3

Abstrak. Persamaan mild-slope yang diturunkan Kirby (1986) dapat diterapkan untuk simulasi transformasi gelombang dari perairan dalam menuju pantai. Pada paper ini dikembangkan model Kirby dengan memperhatikan factor arus. Pengaruh arus pada transformasi gelombang tersebut diselesaikan dengan metode selisih hingga. Berdasarkan verifikasi model numerik dengan analitik menunjukkan bahwa perbedaan kecepatan rata-rata arus longhsore kurang dari 5%, artinya model numerik ini dapat mensimulasikan arus akibat induksi gelombang dengan baik. Verifikasi model gelombang dengan hasil penelitian Johnson (1952), Wiegel (1962) dan Wei (1998) menunjukkan adanya kemiripan, sedangkan perbedaan yang ada karena pada model mempertimbangkanfaktor arus.Abstract. Mild-slope equations have been derived by Kirby (1986) can be applied on simulation of wave transformation from deep water to coastal. This paper's developed Kirby's model with considering current factor. The effect of current on wave transformation have been modeled with finite difference methods. According to verification of numerical models and analytical model, the difference of mean longshore current velocity less than 5%, it means that this numerical model provide good simulation of current caused by wave induction. Verification of wave model on Johnson (1952), Wiegel (1962) and Wei (1998) result similarity, but there's still any difference thismodel considering current factor.

Analisa Tegangan Mooring pada Floating breakwater Tipe Gergaji dengan Pemodelan Fisik Sujantoko Sujantoko; Eko Budi Djatmiko; Wisnu Wardhana; Aditya Hidayatullah
Jurnal Teknik Sipil Vol 28 No 3 (2021): Jurnal Teknik Sipil
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/jts.2021.28.3.6

Abstrak Floating breakwater dapat diaplikasikan sebagai alternatif dari fixed breakwater di perairan pantai dengan kondisi tertentu secara efisien dan efektif, desainnya dapat dielaborasi dengan fleksibel, dan instalasinya lebih mudah. Salah satu aspek dasar dalam desain floating breakwater adalah sistem mooring yang baik, sehingga struktur tersebut dapat berada pada posisinya dan kinerjanya meningkat. Penelitian ini bertujuan untuk menentukan besarnya tegangan mooring maksimum melalui eksperimen pada model floating breakwater tipe gergaji dan ponton. Model floating breakwater dibuat dari bahan polylactic acid dan model tali mooring digunakan jenis polyethylene. Pengujian fisik dilakukan dengan gelombang irreguler dan spektrum JONSWAP di wave flume. Selama pengujian dilakukan berbagai variasi input tinggi gelombang (Hs), periode gelombang (T), kedalaman air (d), dan sudut mooring (q). Hasil penelitian ini menunjukkan nilai tegangan mooring maksimum baik floating breakwater tipe gergaji dan ponton terjadi pada sudut mooring 30⁰ dan kedalaman air 45 cm secara berturut turut sebesar 5.28 N dan 4.91 N, sedangkan tegangan terkecil terjadi pada sudut mooring 60⁰ dan kedalaman air 41 cm yaitu 1,03 N dan 1,27 N. Perbandingan nilai tegangan mooring tipe gergaji pada sudut mooring (30o, 45o, 60o) adalah lebih besar 10.82%-19.71%, 24.00-40.94%, dan 22.2%-39.42% dari tipe ponton pada kedalaman air 41cm, 43cm dan 45cm. Kata-kata kunci: Floating breakwater, model fisik, sudut mooring, tegangan mooring. Abstract Floating breakwater can be applied as an alternative to the fixed breakwater in coastal waters with certain conditions efficiently and effectively, the design can be elaborated flexibly, and the installation is easier. One of the basic aspects in the design of a floating breakwater is a good mooring system so that the structure can be in position and its performance is increased. This study aims to determine the maximum mooring tension through experiments on the saw and pontoon-type floating breakwater models. The floating breakwater model is made of polylactic acid and the mooring rope model is made of polyethylene. Physical testing was carried out with irregular waves and the JONSWAP spectrum in the wave flume. During the test, various input variations of wave height (Hs), wave period (T), water depth (d), and mooring angle (q) were carried out. The results of this study indicate that the maximum mooring tension value for both saw and pontoon floating breakwater occurs at a mooring angle of 30⁰ and a water depth of 45 cm respectively 5.28 N and 4.91 N, while the smallest tension occurs at a mooring angle of 60⁰ and a water depth of 41 cm, namely 1 .03 N and 1.27 N. Comparison of saw-type mooring tension values at mooring angles (30o, 45o, 60o) were 10.82%-1971%, 24.00-40.94%, and 22.2%-39.42% higher than the pontoon type at water depth 41cm, 43cm and 45cm. Keywords: Floating breakwater, physical model, mooring angle, mooring tension.

The Analysis of Wafe Refraction using SWAN Model Sujantoko Sujantoko
IPTEK The Journal for Technology and Science Vol 20, No 2 (2009)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v20i2.123

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.

Study of Changes in Coastal Morphology Due to Utilization of the Surabaya City Coastal Area Sujantoko Sujantoko; Widi Agus Pratikto; Rudi Waluyo Prastianto; Muh. Ilham Maulana; Anggie Vibriyanti
International Journal of Marine Engineering Innovation and Research Vol 7, No 1 (2022)
Publisher : Institut Teknologi Sepuluh Nopember

Indonesia is an archipelagic country with a vast coastal area, so proper management is needed in the development of coastal areas. The city of Surabaya is one of the cities that carry out the development of coastal areas by projecting strategic areas of its coastal areas as regulated in the regional medium-term development plan 2016-2021. The strategic area of the coastal area of Surabaya city is divided into two, namely strategic areas to support economic growth and save the environment. One of the efforts to optimize the development of coastal areas is to examine changes in coastal morphology due to coastal utilization. Analysis of the study was carried out by comparing historical maps of the last 10 years with existing maps from google earth and map analysis using ArcGIS 10.8. The results show that most in the coastal area of north Surabaya there is a change in coastal morphology covering an area of 360,121 m2 as a result of the reclamation of the construction of the Lamong bay port and 623.12 m2 in the coastal area of east Surabaya due to the addition of mangroves. Regular monitoring and improvement efforts on the coast of Surabaya city must be carried out on an ongoing basis, so that coastal threats such as sedimentation and erosion can be minimized

Young Human Resource Development to Support Village SDGs Shade Rahmawati; Mukhtasor Mukhtasor; Agoes Pratikto; Sujantoko Sujantoko; Haryo Dwito Armono; Wisnu Wardhana; Muhammad Zikra; Hasan Ikhwani; Rudi Walujo Prastianto
IPTEK Journal of Proceedings Series No 1 (2023): The 1st International Conference on Community Services and Public Policy (ICCSP) 2022
Publisher : Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j23546026.y2023i1.16377

All states have different histories, cultures and local wisdom which then influence how the Sustainable Development Goals (SDGs) are applied to their development plan. The specific characters of Indonesian villages leads the government to establish the 18th SDGs called Village SDGs in 2020. The Village SDGs program emphasizing one message: no one left behind. In relation to this, the roles of young human resources in order to succeed the bottom-to- top development in the villages are crucial. In an effort to develop the village, the community, especially the youth, must not lose their identity. Following those condition, a community service program regarding young human resource development has been executed in partnership with Youth Information and Counseling Center (or Pusat Informasi dan Konseling Remaja) of Krecek Village, Kediri Regency. The development program is concentrating on the basic understanding of their role in society, moral values, adolescent health and family functioning. Two- days coaching which involves Family Planning Counseling Center (or Balai Penyuluhan KB) and Bureau of Population Control, Family Planning, Women's Empowerment and Child Protection (DP2KBP3A) of Kediri Regency was held as the first step. Evaluation regarding further needs from the participants are being obtained.

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