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RESPON SINGKAT KONSENTRASI KLOROFIL-A TERHADAP PERUBAHAN ARUS EDDY PERMUKAAN DI WILAYAH PERAIRAN TELUK TOLO DAN SEKITARNYA
Get PDFUpwelling, sebuah proses oseanografi yang sangat penting, memperkaya air permukaan dengan massa air yang kaya nutrisi dari lapisan yang lebih dalam. Upwelling dapat terjadi sebagai respon dari dinamika arus eddy, dan ini kami temukan salah satunya di perairan Teluk Tolo dan sekitarnya. Penelitian ini menganalisis pengaruh arus eddy terhadap upwelling di wilayah tersebut dengan menggunakan data citra satelit dari Copernicus Marine Environment Monitoring Service (CMEMS), Copernicus Climate Change Service (C3S) dan model klimat dari ECMWF Reanalysis v5 (ERA 5). Data suhu permukaan laut (SST), klorofil-a permukaan laut (SSC), tinggi permukaan laut (SSH), dan angin permukaan laut (SSW) digunakan untuk memahami bagaimana arus eddy memengaruhi upwelling di wilayah kajian selama periode 15 tahun pengamatan (tahun 2006 hingga 2020). Hasil penelitian menunjukkan jumlah arus eddy yang terbentuk adalah 341 buah (195 buah untuk eddy siklonik (CE) dan 146 buah untuk eddy antisiklonik (AE)). Jumlah maksimum CE (AE) ditemukan pada bulan Januari dan Juni (bulan Juli dan Oktober) serta minimum pada bulan September (bulan Mei). CE menyebabkan anomali negatif SST serta anomali positif SSC dengan perubahan signifikan setelah dua hari CE terbentuk. Karakteristik anomali SST dan SSC pada CE didukung melalui nilai EPV (Ekman pumping velocity) positif (maksimum 3,5x10-6 m/s) yang mengindikasikan adanya upwelling. Sedangkan AE menyebabkan anomali positif SST serta anomali negatif SSC, dan mulai berubah tiga hari setelah AE terbentuk dengan nilai EPV negatif (minimum -1,1x10-6 m/s) yang menandakan adanya downwelling. Pengaruh eddy pada perairan Teluk Tolo dan sekitarnya terhadap upwelling lebih dominan dibandingkan dengan pengaruh angin pada bulan Juni, Juli, dan Agustus
ANALISA PROFIL DASAR LAUT DAN KARAKTERISTIK SEDIMEN MENGGUNAKAN MULTIBEAM ECHOSOUNDER DI PERAIRAN JAKARTA
Get PDFProfil dan karakteristik sedimen dasar laut menjadi informasi penting dalam kegiatan pengerukan alur Pelabuhan. Dasar sedimen yang bervariasi dan area pengerukan yang luas harus dapat dipetakan, serta dianalisa secara tepat agar memudahkan kegiatan pengerukan. Teknologi multibeam echosounder(MBES) dapat digunakan untuk mendeteksi kedalaman dan merekam data pantulan dasar laut, yang kemudian diproses menjadi mozaik pantulan sehingga membantu mengidentifikasi jenis dan morfologi dasar laut. Penelitian ini dilaksanakan di alur Pelabuhan Rukindo perairan Jakarta yang merupakan ordo khusus dengan kedalaman bervariasi. Penelitian ini dilakukan menggunakan data in situ MBES dengan menganalisis nilai hamburan balik (backscatter) metode Angular Range Analysis dan Sediment Analysis Tools (ARA&SAT) dimana hubungan hamburan balik sangat erat dengan ukuran butiran sedimen. Validasi dilaksanakan dengan pengambilan sedimen, menggunakan grab sample sebanyak 12 titik di area penelitian, kemudian melaksanakan pengujian contoh sedimen di laboratorium untuk menghasilkan klasifikasi sedimen skala wenthworth. Penelitian ini bertujuan untuk memberikan gambaran hasil pengujian sedimen dengan nilai backscatter MBES dan hasil penelitian ini diharapkan menjadi dasar pengklasifikasian sedimen halus berdasarkan nilai backscatter di laut Jakarta. Hasil dari penelitian ini didapatkan nilai intensitas sedimen dari backscatter MBES antara -15 db s.d -30 db dengan 3 klasifikasi sedimen yang didominasi oleh sedimen pasir halus. Berdasarkan nilai backscatter MBES diharapkan diketahui klasifikasi jenis sedimen sehingga berkontribusi untuk perencanaan pengerukan alur pelabuhan terkait dengan jenis substrat bawah laut sehingga kegiatan pengerukan dapat dilakukan dengan aman dan efektif
MIOCENE PALEOGEOGRAPHIC RECONSTRUCTION IN THE SANGATTA AREA, EAST KALIMANTAN BASED ON CALCAREOUS NANNOFOSSIL BIOSTRATIGRAPHY AND BENTHONIC FORAMINIFERAL ANALYSIS
Get PDFThe Kutai Basin is a significant hydrocarbon potential basin with up to 15 km thickness of Tertiary sediments. It is dominated by a complex deltaic system to a marine shelf environment. Thus, it is crucial to understand the facies distribution in the area. This study was carried out to assess, correlate, and reconstruct the paleoceanographic evolution of the basin using lithological and microfossil data obtained from five exploration wells. The lithostratigraphic analysis was used to identify lithological units of each well, while the calcareous nannofossils biostratigraphy was applied to estimate the age and benthic foraminifera was analysed for paleoenvironmental interpretation. The findings reveal that the study region consisted of claystone, siltstone, shale, coal, and sandstone of the Gelingseh and Kelandasan Formation. The age of these lithological units is assigned from the Middle to Late Miocene epoch (NN6-NN11), based on the presence of some nannofossil index fossils such as Catinaster coalitus, Discoaster hamatus, Discoaster quinqueramus, Discoaster calcaris, and Coronocyclus nitescens. Benthic foraminifera assemblages are primarily composed of arenaceous species such as Trochamina spp. and Haplophragmoides spp., indicating a transitional environment, though some species such as Elphidium spp. and several planktonic foraminifera species appeared, which reflect marine influence on the research area. Based on the biofacies analysis; mudflats, tidal flats, delta front, prodelta-marine shelf, and fluvial plain were formed during the Middle to Late Miocene in the studied area
PEMODELAN GELOMBANG DAN ARUS PADA DESAIN GROIN DI PPI CISOLOK, SUKABUMI
Get PDFFasilitas pokok dermaga pendaratan ikan dan kolam pelabuhan di Pangkalan Pendaratan Ikan Cisolok tidak dapat menampung seluruh jumlah kapal ikan nelayan karena kondisi fasilitas yang ada sudah rusak dan terjadi sedimentasi di kolam pelabuhan. Tujuan penelitian ini adalah mengkaji pengaruh gelombang dan arus sejajar pantai di sekitar PPI Cisolok lalu merencanakan desain groin yang efektif agar dapat melindungi kolam pelabuhan dari arus sejajar pantai yang membawa sedimen. Simulasi hidrodinamika dan transformasi gelombang dilakukan dengan MIKE 21 Modul Flow Model Flexible Mesh dan Modul Spectral Wave. Pada alternatif 1 groin diperpanjang 85 m tegak lurus pantai dan alternatif 2 diperpanjang 90 m dengan posisi ke arah tenggara. Hasil analisis pada pemodelan transformasi gelombang menunjukan bahwa desain groin alternatif 2 lebih efektif untuk melindungi kolam pelabuhan dari gelombang dan arus sejajar pantai dengan persentase reduksi di musim barat sebesar 46% dan di musim timur sebesar 43.5%
GEOLOGICAL INTERPRETATION OF NORTH MADURA OFFSHORE SEDIMENTARY BASIN BASED ON GRAVITY DATA ANALYSIS
Get PDFThe area of north Madura offshore is one of the sedimentary basins within the North East Java Basin which has interesting paleogeographical developments. These developments are the result of various sedimentation processes and changes in the depositional environments. The purpose of this study is to identify subsurface geological structures, delineate sedimentary sub-basins, and estimate sediment thickness. For that, we do spectrum analysis, optimum upward continuation filtering, spectral decomposition analysis, 2D forward modeling and 3D inversion of gravity data. The results of the spectral analysis show that the average thickness of sedimentary rocks in the study area is around 3.788 km. From the gravity data analysis, 10 sedimentary sub-basins were delineated, indicating structural patterns of basement high, grabens, and faults. 2D and 3D modeling revealed four layers of stratigraphy, in order from youngest to oldest are Tertiary-Neogene sedimentary rocks with a density value of 2.1 gr/cc, the Tertiary-Neogene sedimentary rocks with a density of 2.3 gr/cc, the Tertiary - Paleogene sedimentary rocks with a density of 2.45 gr/cc, and the basement layer identified as volcanic igneous rock with a density of 2.67 gr/cc
LITHOLOGY AND RESERVOIR IDENTIFICATION IN THE “EL” WELL, EAST JAVA USING SEISMIC INVERSION
Get PDFThe acoustic impedance inversion seismic method, carried out at the "EL" well in East Java,provides a description of the physical properties of subsurface rocks. This method involves identifying rocklayers, lithology types, porosity values, the presence of hydrocarbons, and fluids in the target zone usingboth well data and integrated seismic data. The data processing included the cross-plotting of acousticimpedance (AI) with gamma ray logs, porosity logs, and resistivity logs. We integrated seismic and welldata, picked horizons, and created AI inversion models. The based model inversion technique was used tocompare the synthetic model with the seismic data, aiming to obtain an AI value that closely represents theactual model. AI seismic inversion effectively separates lithological boundaries vertically and laterally,based on the selected picking horizon and created model. To enhance understanding of the lithology andhydrocarbon prospect zone in the study area, a cross-plot analysis was used to correlate the seismic inversionmodel. The results reveal that the study area represents a hydrocarbon prospect zone, with reservoir rocksconsist of coral and foram at a depth range of 2320 - 2430 ft
ACOUSTIC CHARACTERISTICS OF SIDESCAN SONAR ALONG PROPOSED POWER CABLE ROUTE, DUMAI – RUPAT ISLAND
Get PDFCable power installation along the route with bedforms-sediment structures sometimes potentially to have problems in the future or near future. In order to mitigate the cable from exposure because of currents, it is important to know a detailed understanding of the seabed and its mobility. Seabed characteristics, either textures or sediment structures, could be interpreted from acoustic characters, one of which is based on sidescan sonar images. An automatic interpretation to classify seabed characteristics can be done by using an image processing software. Image processing has been done on sidescan sonar images along power cable route between Dumai and Rupat Island. The image processing was using simple textures and Grey-Level Co-occurrence Matrix (GCLM) textures. Manual interpretation of sidescan sonar images classifies the acoustic characters into six; (1) fine sand waves with ripple marks, wave length 2.5-4 meters, (2) fine sands, (3) fine sand waves with ripple marks, wave length 5-9 meters, (4) fine sand with ripple-mega ripples, (5) coarse sands with ripple-trawl marks, and (6) very fine sands. The results of automatic classification show that image processing with simple textures is unable to identify the textures and structures of sediments properly, but by combining simple texture classification and GCLM types of sediment textures and sediment structures are better identified. This classification results are in agreement with the results of manual interpretation of sidescan sonar images