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All Journal BULETIN OSEANOGRAFI MARINA Jurnal Kelautan Tropis JURNAL TEKNIK HIDRAULIK Indonesian Journal of Oceanography

Rikha Widiaratih

Departemen Oseanografi, Fakultas Perikanan Ilmu Kelautan, Universitas Diponegoro Jl. Prof. H. Sudarto, SH, Tembalang, Kota Semarang, Kode Pos 50275 Telp/fax (024) 7474698

Author-ID : 2958167

Agriculture, Biological Sciences & Forestry Civil Engineering, Building, Construction & Architecture Decision Sciences, Operations Research & Management Earth & Planetary Sciences Engineering Environmental Science

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Sedimentasi dan Abrasi di Pantai Bandengan, Kabupaten Jepara Daniel Giovanni Sihotang; Heryoso Setiyono; Petrus Subardjo; Alfi Satriadi; Hariyadi Hariyadi; Rikha Widiaratih; Azis Rifai
Indonesian Journal of Oceanography Vol 2, No 4 (2020): Indonesian Journal of Oceanography
Publisher : University of Diponegoro

Pantai Bandengan merupakan salah satu pantai wisata di Kabupaten Jepara dimana terjadi aktifitas pembangunan yang cukup massif sejak beberapa tahun terakhir yang bertujuan untuk menunjang kegiatan rekreasi wisatawan. Namun terdapat ancaman dalam pengembangan sektor wisata tersebut berupa perubahan garis pantai yang disebabkan oleh sedimentasi dan abrasi yang dapat mengganggu perekonomian masyarakat yang memiliki mata pencaharian di wilayah tersebut. Tujuan penelitian ini yakni untuk mengetahui dampak sedimentasi dan abrasi terhadap luas daratan serta mengidentifikasi wilayah-wilayah yang rawan terhadap perubahan garis pantai. Metode yang digunakan yaitu interpretasi citra satelit Google Earth Pro serta survei lapangan menggunakan alat Sediment trap dan bola duga. Pengolahan data citra diproses menggunakan software ArcGIS 10.2 untuk mendapatkan luasan wilayah sedimentasi serta abrasi. Sediment trap digunakan untuk mendapatkan laju sedimentasi dan karakteristik sedimen. Berdasarkan hasil penelitian, dalam lima tahun terakhir sejak 2015 hingga 2019 terjadi sedimentasi seluas ± 8062,9 m2, sedangkan abrasi seluas ± 12.502,1 m2. Sedimen penyusun perairan didominasi oleh lanau pasiran serta kecepatan arus permukaan berkisar 0,085 m/s hingga 0,197 m/s. Bandengan beach is one of the tourist beaches in Jepara Regency where there have been massive development activities since the last few years aimed at supporting tourist recreational activities. However, there is a threat in the development of the tourism sector in the form of changes in the coastline caused by sedimentation and abrasion that can disrupt the economy of people who have a livelihood in the region. The purpose of this research is to determine the impact of sedimentation and abrasion on land area and identify areas that are prone to shoreline changes. The method used is the interpretation of Google Earth Pro satellite imagery and field surveys using a Sediment trap and floating ball. Image data processing is processed using ArcGIS 10.2 software to get the area of sedimentation and abrasion. Sediment traps are used to obtain sedimentation rates and sediment characteristics. Based on the results of the study, in the last five years since 2015 until 2019 there is a sedimentation area of ± 8.062,9 m2, while abrasion area of ± 12.502,1 m2. The constituent sediments of the waters are dominated by the sandy silt and surface current velocity ranges from 0.085 m/s to 0.197 m/s.

Studi Sebaran Material Padatan Tersuspensi Di Muara Sungai Sambong, Kabupaten Batang Ahmad Fikri Delardi; Siddhi Saputro; Warsito Atmodjo; Heriyoso Setyono; Rikha Widiaratih; Aris Ismanto
Indonesian Journal of Oceanography Vol 1, No 1 (2019): Indonesian Journal of Oceanography
Publisher : University of Diponegoro

Muara Sungai Sambong berpotensi mengalami pendangkalan akibat pengendapan sedimen tersuspensi. Kali Sambong terus mengalami pendangkalan karena sedimentasi dan sampah sekaligus alur menuju muara pantai yg mengalami penyempitan. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh arus dalam persebaran MPT di Muara Sungai Sambong, Kabupaten Batang, Jawa Tengah. Penelitian dimulai dari tahap pengambilan data di lapangan pada tanggal 7-9 Maret 2017 di Perairan Muara Sungai Sambong, Batang dan tahap pengolahan serta analisis data hasil pengukuran lapangan. Materi yang digunakan meliputi data primer berupa sampel air laut serta data lapangan kecepatan dan arah arus saat pasang maupun surut selama 3 hari, sedangkan data sekunder berupa data pasang surut bulan Maret 2017 dan citra GeoEye tahun 2017. Penelitian ini menggunakan metode analisis kuantitatif model, penentuan lokasi pengambilan sampel air menggunakan metode purposive sampling, pengambilan data arus menggunakan metode lagrange. Model matematik yang digunakan adalah Mike21 Flow Model FM untuk pola arus dan metode interpolasi sebaran MPT dengan ArcGIS menggunakan metode Natural Neighbor. Berdasarkan hasil dari penelitian ini menunjukkan bahwa kecepatan arus pada kondisi pasang menuju surut memiliki nilai antara 0,168 m/dt – 1,111 m/dt, sedangkan pada kondisi surut menuju pasang memiliki nilai antara 0,164 m/dt – 1,25 m/dt. Nilai material padatan tersuspensi pada kondisi pasang menuju surut memiliki nilai antara 0,08 – 0,29 g/L, sedangkan pada kondisi surut menuju pasang memiliki nilai antara 0,06 – 0,35 g/L. Berdasarkan hasil penelitian dapat disimpulkan bahwa pengaruh arus terhadap sebaran konsentrasi MPT, cukup tinggi. Sambong Estuary potentially suffering to shallow as the result of suspended sedimentation. Sambong River is shallowing due to sedimentation and debris which also narrowing the river channel. The purpose of this study is to observe the effect of current to Total Suspended Solid (TSS) distribution in Sambong Estuary, Batang Regency, Central Java. The study was begin from field collecting data on 7-9 March 2017 in Sambong Estuary waters, Batang and then the data proceed and analized. Material of this study was consist of primary data, which are seawater sampel, current velocity and direction while tide and neap, and secondary data, which are tidal data on March 2017 and GeoEye image on 2017. Quantitative model analysis was used in this study, purposive sampling method was used on collecting the water sampel and lagrange method was used for current data collecting. Mike21 Flow Model FM was used for current model and TSS interpolation method was using ArcGIS by Natural Neighbor method. The result of this study showed that current velocity in tide to neap condition was 0.168 m/s – 1.111 m/s, while in neap to tide condition was 0.164 m/s – 1.25 m/s. Total Suspended Solid value tide to neap condition was 0.08 g/L – 0.29 g/L, while in neap to tide condition was 0.06 g/L – 0.35 g/L. According to this study the effect of current to TSS was high.

Spatial Structure Analysis of Benthic Ecosystem Based on Geospatial Approach at Parang Islands, Karimunjawa National Park, Central Java, Indonesia Muhamamd Helmi; Afrina Aysira; Munasik Munasik; Anindya Wirasatriya; Rikha Widiaratih; Raden Ario
Indonesian Journal of Oceanography Vol 2, No 1 (2020): Indonesian Journal of Oceanography
Publisher : University of Diponegoro

This research examines the spatial structure of live coral based on its patches on a geospatial data. Spatial structure is a part of the landscape ecology approach that has been applied on terrestrial and applied on marine ecosystems on this research. It is including Mean Shape Index (MSI), Number of Patches (NumP), Mean Patch Size (MPS), Total Seascape Area (TLA) and Class Area (CA). Live coral patches were extracted based on GeoEye-1 satellite image with several tasks, such as ortho-rectification, atmospheric calibration, water column correction; Lyzenga transform and supervised classification. A field survey was done in 2015 - 2016 with 38 verification sites and 16 sites of manta tow. Live coral patches produced a significant accuracy (overall accuracy=84.1%, user accuracy= 81.8%, producer accuracy = 90%, and Kappa Index k = 0.81%). Live coral was found 35% (CA: 201.99 ha) of seascape TLA area 814.19 ha and spread over a large number of patches (NumP: 5613-21087 patches). The live coral had a mean shape index (MSI) between 1.23 to 1.25 and the average size of patches (MPS) between 0.0029 - 0.0082. This approach could be applied to reef ecosystems and becomes a baseline data to anticipate future damage.

Karakteristik Mikroplastik Di Perairan Pulau Tengah, Karimunjawa Salsabila Salsabila; Elis Indrayanti; Rikha Widiaratih
Indonesian Journal of Oceanography Vol 4, No 4 (2022): Indonesian Journal of Oceanography
Publisher : University of Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/ijoce.v4i4.15420

Abstrak Mikroplastik merupakan partikel plastik berukuran mikro (<5 mm). Ukurannya yang kecil dan ketahanannya yang lama menyebabkan mikroplastik berbahaya jika terakumulasi di dalam tubuh makhluk hidup. Tujuan dari penelitian ini adalah untuk mengidentifikasikan karakteristik mikroplastik yang berada di Pulau Tengah, Karimunjawa. Sampel mikroplastik diambil pada 12 April 2021 di 4 stasiun. Sampel air laut diambil menggunakan plankton net dan diukur parameter fisika dan kimianya. Sampel kemudian dilarutkan dalam larutan etanol 96%, H2O2 30%, selanjutnya disaring menggunakan vacuum pump untuk didapatkan partikel mikroplastik. Partikel mikroplastik diamati kelimpahan dan bentuknya menggunakan mikroskop stereo, lalu dianalisis jenis polimernya dengan alat FTIR. Hasil penelitian menunjukkan kelimpahan total mikroplastik yang terdapat di perairan Pulau Tengah sebesar 142,44 partikel/m3. Jenis mikroplastik dalam sampel air laut adalah fiber, fragment, film, dan pellets. Warna mikroplastik yang ditemukan adalah hitam, biru, merah, cokelat, kuning, tranparant, dan hijau. Hasil Uji FT-IR jenis polimer mikroplastik yang ditemukan adalah Nitril, HDPE, LDPE, PVA, dan PP. Mikroplastik berbentuk fragmen paling banyak ditemukan di semua stasiun, dengan kelimpahan 90,3 partikel/m3 dan mikroplastik berwarna hitam paling banyak ditemukan, dengan kelimpahan 74,1 partikel/m3. Mikroplastik yang berada di Perairan Pulau Tengah memiliki potensi untuk mengkontaminasi terumbu karang yang berada di sekitar perairan tersebut.Kata kunci : Pulau Tengah, Mikroplastik, Kelimpahan, FTIRAbstractMicroplastics are micro-sized plastic particles (<5 mm). Its small size and long durability make microplastics dangerous if they accumulate in the body of living things. The purpose of this study was to identify the characteristics of microplastics in Central Island, Karimunjawa. Microplastic samples were taken on April 12, 2021 at 4 stations. Sea air samples were taken using a plankton net and measured physical and chemical parameters. The sample was then dissolved in 96% ethanol solution, 30% H2O2, then filtered using a vacuum pump to obtain microplastic particles. Microplastic particles were observed and their shape using a stereo microscope, then the type of polymer was analyzed by means of FTIR. The results showed that the total microplastic found in the waters of Central Island was 142.44 particles/m3. The types of microplastics in seawater samples are fiber, fragment, film, and pellet. The colors of the microplastics found were black, blue, red, brown, yellow, transparent, and green. The results of the FT-IR test of the types of microplastic polymers found were Nitrile, HDPE, LDPE, PVA, and PP. Microplastics in the form of fragments were found at all stations, with 90.3 particles/m3 and black microplastics were the most commonly found, with 74.1 particles/m3. Microplastics in Central Island waters have the potential to contaminate coral reefs around these waters.Keywords : Central Island, Microplastics, Abundance, FTIR

Analisis ENSO terhadap Variabilitas Kedalaman Mixed Layer di Laut Maluku Adinda Rizki Amalia; Anindya Wirasatriya; Rikha Widiaratih
Indonesian Journal of Oceanography Vol 5, No 1 (2023): Indonesian Journal of Oceanography
Publisher : University of Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/ijoce.v5i1.15697

Kondisi oseanografi di perairan Maluku dipengaruhi oleh variabilitas iklim ENSO salah satunya adalah kedalaman mixed layer. Menggunakan data satelit observasi dan data model untuk mengetahui kondisi angin, suhu permukaan laut dan kedalaman mixed layer tebal jangka waktu 10 tahun, penelitian ini bertujuan untuk mengetahui pengaruh ENSO terhadap ketebaln mixed layer di perairan Maluku. Dengan mengginakan data kedalaman mixed layer dari Marine Copernicus, kami menemukan bahwa saat periode El-Niño (2015/2016) pada wilayah upwelling mengalami penipisan sebesar 2 meter sedangkan pada wilayah yang tidak terjadi upwelling mengalami penebalan sebesar 1- 2 meter. Saat periode La-Niña (2010/2011) tidak mengalami upwelling sehingga perairan ini mengalami penipisan hingga 7 meter pada seluruh perairan Maluku. Fenomena ini sangat berkaitan dengan kondisi angin di perairan Maluku.Kata kunci: ENSO, Suhu Permukaan Laut, Angin, Kedalaman Mixed Layer dan Perairan Maluku Oceanographic conditions in Maluku Seas are influenced by ENSO climate variability, one of which is the mixed layer depth. Using satellite observation and model data to determine wind, sea surface temperature and mixed layer depth condition in a period 10 years, this study aims to determine the influence of ENSO on the mixed layer depth in Maluku Seas. Using mixed layer depth data from Marine Copernicus, we found that during the El-Niño (2015/2016) the upwelling area experienced a shallower 2 meters while in the area that did not occur upwelling experienced a deeper 1-2 meters. During the La-Niña (2010/2011) there was no upwelling so that these seas experienced shallower up to 7 meters in Maluku Seas. This phenomenon is clearly related to wind conditions in the Maluku Seas.Keywords: ENSO, Sea Surface Temperature, Mixed Layer Depth, Winds, and Maluku Seas

Co-Authors A Aziz Alfani Abdillah Ranadipura Adinda Rizki Amalia Afrina Aysira Ahmad Fikri Delardi Alfi Satriadi Anindya Wirasatriya Aris Ismanto Azis Rifai Bagaskoro Cahyo Fauzan Baskoro Rochaddi Daniel Giovanni Sihotang Denny Nugroho Sugianto Durmont Siahaan Dwi Haryo Ismunarti Elis Indrayanti Fernandito Suryo Hutomo Gentio Harsono Gentur Handoyo Ginnia Julianti Utomo Hariyadi Hariyadi Heriyoso Setyono Heryoso Setiyono Ibnu Pratikto Jarot Marwoto Kunarso Kunarso Larosa Nurfikri Gamellia Lilik Maslukah Maratus Khasanah Humairah Maria Griselda Novita Muh Dandi Firmansyah Muhamad Adnan Kurnianto Muhamamd Helmi Muhammad Helmi Muslim Muslim Nanda Rahmadi Nugroho Agus D Nurfatin Adibah Petrus Subardjo Purwanto Purwanto Putranto Kondang Wijaya Raden Ario Salsabila Salsabila Siddhi Saputro Sri Yulina Wulandari Sugeng Widada Surya Nugraha Syaiful Tamara Centong Mandey Theresa Pinkan Gustya Primasti Warsito Atmodjo Yeremia Sudibyo

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