Electronic Theses and Dissertation

Perairan Aceh terletak diantara Samudera Hindia, Pulau Sumatera, dan Selat Malaka. Adapun aktivitas di perairan Aceh dan sekitarnya adalah kegiatan pelayaran, pelabuhan, penambangan, pertambakan dan perikanan serta pariwisata. Segala aktivitas tersebut dipengaruhi hidrodinamika dan dinamika sedimen. Penelitian hidrodinamika dan sedimen yang dilakukan sebelumnya di Aceh antara lain tentang pasang surut laut, sirkulasi arus, energi laut, statistik sedimen dasar dan sedimen tersuspensi. Selanjutnya penelitian transpor sedimen dekat pantai dan estuari umumnya disebabkan oleh gelombang, arus pasang surut, dan arus akibat gelombang. Gelombang dan arus adalah faktor penting transpor sedimen pada perairan pantai dan estuari dalam mendukung, menjaga atau memproteksi segala aktivitas di sekitar perairan, sehingga kajian sirkulasi arus dan transpor sedimen perlu dilakukan secara mendalam. Permasalahan dalam penelitian ini adalah bagaimanakah sirkulasi arus dan transpor sedimen di perairan Aceh untuk diteruskan ke stakeholders untuk kontrol marine protected area (MPA), kontrol kualitas air, pengembangan pelabuhan, industri sekitar pantai, lepas pantai, dan aktivitas penangkapan ikan. Berdasarkan masalah tersebut, maka tujuan penelitian ini adalah (1) menelaah proses sirkulasi arus perairan Aceh; (2) mengkaji pola transpor sedimen di wilayah perairan Aceh serta (3) menganalisis arus dan distribusi konsentrasi sedimen di lingkungan laut.
Hasil-hasil penelitian menghasilkan hidrodinamika 2D hidrostatik akibat pasang surut dan hidrodinamika 3D non hidrostatik akibat angin, pasang surut laut, perbedaan densitas yang dikombinasikan dengan transpor sedimen. Hasil penelitian hidrodinamika 2D hidrostatik di Western Waters of Aceh (WWA) menunjukkan bahwa amplitudo pasang surut M2 berkisar antara 14 cm dan 17 cm. Nilai terendah berada di tengah WWA, sedangkan nilai tertinggi berada di barat laut (NW). Di tenggara (SE), amplitudo adalah 15 cm. Nilai fase berada dalam kisaran 0 sampai 40 derajat yang menunjukkan bahwa gelombang pasang surut M2 bergerak dari SE ke NW. Elips arus menunjukkan rotasi berlawanan arah jarum jam. Arus residu yang diperoleh dari elips arus bergerak dari SE ke NW. Berdasarkan amplitudo pasang surut M2, disimpulkan bahwa gelombang pasang surut M2 berdampak lemah terhadap arus pasang surut di WWA. Amplitudo semi-mayor elips arus menunjukkan nilai yang relatif lebih tinggi di WWA bagian barat dibandingkan dengan WWA bagian timur. Arus residu cukup kuat di perairan dangkal dekat garis pantai WWA.
Hasil penelitian hidrodinamika 3D non hidrostatik menunjukkan kesesuaian yang baik dengan data TMD. Begitu juga time series pasang surut yang dihasilkan dari model menunjukkan kesesuaian dengan data TMD pada stasiun Lhoknga, Ulee Lheue, Lampulo dan Alue Naga. Dari hasil simulasi diperoleh bahwa arus permukaan dan dasar laut pada Agustus 2019 lebih kuat bila dibandingkan dengan Februari 2019 pada bagian barat NWA, kecuali pada 5,57LU; 5,59LU; 5,60LU. Arus permukaan lebih besar di bagian utara NWA jika dibandingkan pada bagian barat NWA. Sedangkan sirkulasi arus dasar laut pada Februari 2019 di bagian Utara menuju Barat, Utara, Selatan NWA dan pada Agustus 2019 menuju Barat, Utara, Selatan, Timur NWA. Selanjutnya berdasarkan hasil model hidrodinamika dan transpor sedimen, nilai distribusi konsentrasi total suspended sediment (TSS) permukaan lebih rendah di bulan Agustus 2019 daripada di bulan Februari 2019. Berikut hasil verifikasi konsentrasi TSS permukaan antara model dan Visible Infrared Imaging Radiometer Suite (VIIRS) menunjukkan kesesuaian.
Dengan demikian novelty penelitian ini yaitu distribusi konsentrasi total suspended solid (TSS) dengan model hidrodinamika 3D non hidrostatik telah berhasil dicapai dan stabil dengan menyesuaikan parameter faktor gesekan dasar r, koefisien eddy horizontal A_H dan vertikal A_Z.
Kata Kunci: Arus permukaan laut (0-10 m), Arus dasar laut, Pasang surut, Distribusi konsentrasi TSS.

The waters of Aceh are situated between the Indian Ocean, Sumatra Island, and the Malacca Strait. Various activities take place in and around Aceh waters, such as shipping, port operations, mining, aquaculture, fishing, and tourism. These activities are influenced by hydrodynamics and sediment dynamics. Previous research in Aceh has focused on tidal fluctuations, current circulation, marine energy, bottom sediment statistics, and suspended sediments. Transport of sediment near the coast and estuaries is mainly driven by waves, tidal currents, and wave-induced currents. Waves and currents play crucial roles in sediment transport in coastal waters and estuaries, impacting and supporting various activities in the surrounding areas. Therefore, in-depth studies on current circulation and sediment transport are essential for stakeholders involved in marine protected area (MPA) management, water quality control, harbor development, coastal and offshore industries, and fishing activities. The objectives of this research are to (1) examine the processes of current circulation in Aceh waters, (2) investigate sediment transport patterns in the region, and (3) analyze current and sediment concentration distributions in the marine environment. The research results revealed both 2D hydrostatic hydrodynamics due to tidal fluctuations and 3D non-hydrostatic hydrodynamics influenced by wind, tidal currents, and density differences combined with sediment transport. The 2D hydrostatic study in the Western Waters of Aceh (WWA) showed tidal amplitudes for M2 ranging from 14 cm to 17 cm. The lowest values were found in the central WWA, while the highest values were observed in the northwest (NW). In the southeast (SE) area, the amplitude was 15 cm. The phase values ranged from 0 to 40 degrees, indicating that the M2 tidal wave moved from SE to NW. Ellipses of current showed counterclockwise rotation, and the residual currents obtained from the ellipse showed movement from SE to NW. The study concluded that the M2 tidal wave had a weak impact on tidal currents in WWA. The semi-major axis of the current ellipses showed relatively higher values in the western part of WWA compared to the eastern part. Strong residual currents were found in shallow waters near the WWA coastline. In the 3D non-hydrostatic hydrodynamics study, the results demonstrated good agreement with TMD data. The tidal time series generated by the model also showed agreement with TMD data at stations Lhoknga, Ulee Lheue, Lampulo, and Alue Naga. The simulations showed that surface and bottom currents were stronger in August 2019 than in February 2019 in the western part of the study area, except for certain latitude points. Surface currents were larger in the northern part of the study area compared to the western part. As for the circulation of bottom currents, in February 2019, they moved northward and westward, while in August 2019, they moved westward, northward, southward, and eastward. Based on the hydrodynamic and sediment transport model results, the distribution of surface total suspended sediment (TSS) concentrations was lower in August 2019 than in February 2019. Verification of the surface TSS concentrations between the model and Visible Infrared Imaging Radiometer Suite (VIIRS) data showed agreement. The novelty of this research lies in the successful and stable achievement of the distribution of total suspended solids (TSS) concentrations using a 3D non-hydrostatic hydrodynamic model, adjusting the parameters of the bottom friction factor (r), horizontal eddy coefficient (A_H), and vertical eddy coefficient (A_Z). Keywords: Sea surface current (0-10 m), sea bottom current, tides, distribution of TSS concentration.