Analisis Pola Erosi dan Sedimentasi, serta Perubahan Morfologi Muara dan Pantai Manikin, Pulau Timor, Nusa Tenggara Timur

Kolo, Alexandro Timotius (2025) Analisis Pola Erosi dan Sedimentasi, serta Perubahan Morfologi Muara dan Pantai Manikin, Pulau Timor, Nusa Tenggara Timur. Masters thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Sungai Manikin bermuara di bagian utara Kabupaten Kupang, Nusa Tenggara Timur. Pada kawasan muara Sungai Manikin dan sekitarnya, terdapat pemukiman penduduk, persawahan, perkebunan, tempat aktivitas nelayan, dan sebagainya. Muara Sungai Manikin merupakan area yang cukup vital sebagai penghubung aliran sungai dengan laut, dan mempengaruhi ekosistem pesisir serta aktivitas manusia. Penelitian ini bertujuan menganalisis sedimentasi dan erosi, juga perubahan morfologi di muara dan pantai oleh pengaruh debit sungai, pasang surut, dan gelombang.
Studi ini mengadopsi pendekatan dengan melakukan pemodelan numerik Delft3D untuk mensimulasikan pengaruh sungai, pasang surut dan gelombang laut dalam menginduksi proses angkutan sedimen yang terjadi. Data sedimen yang digunakan adalah sedimen dasar (d50) dan konsentrasi sedimen suspensi. Sementara itu, data debit diperoleh dari data tinggi muka air yang dikonversi menjadi data debit sungai. Gelombang laut menggunakan model gelombang spectral SWAN dengan menggunakan data analisis tinggi dan periode gelombang dari ECMWF ERA 5-Reanalysis. Model dilakukan dengan kombinasi arus dan gelombang (flow coupling wave), dan model arus tanpa gelombang untuk melihat pengaruh arus dan gelombang dalam proses angkutan sedimen. Adapun pemodelan dalam empat musim yakni musim barat (basah), peralihan musim barat-timur, musim timur (kering), dan peralihan musim timur-barat untuk melihat tingkat erosi dan sedimentasi yang terjadi di musim yang berbeda.Hasil penelitian menunjukkan bahwa proses erosi dan sedimentasi umunya terjadi di kawasan muara dan pantai dengan pengaruh gelombang laut yang lebih dominan. Musim barat terjadi erosi dan sedimentasi oleh pengaruh gelombang tinggi dan peningkatan debit yang tinjukkan dengan erosi dan sedimentasi yang menyusur pantai dan kawasan muara dengan ketebalan erosi 0,10 – 0,60 m sedimentasi 0,10 -0,50 m. Angkutan sedimen total pada musim basah berkisar 0,00001 – 0,6550 kg/s/m. Aliran sungai dan proses pasang surut umumnya lebih berpengaruh terhadap proses erosi dan sedimentasi di area sungai. Pada musim timur erosi dan sedimentasi lebih rendah dibandingkan musim barat yang hanya dipengaruhi oleh gelombang dan arus balik pasang surut dengan ketebalan erosi 0,10 – 0,40 dan sedimentasi 0,10 – 0,40 m. Angkutan sedimen total pada musim berada di bawah 0,05 kg/m/s. Debit sungai yang kecil saat musim kemarau menunjukkan pengaruh yang lebih dominan dari gelombang laut saat proses angkutan sedimen yang terjadi di musim timur, meskipun ketinggian gelombang relative lebih rendah dibandingkan tinggi gelombang di musim barat. Adapun perubahan garis pantai selama pemodelan 185 hari (01 Jun-02 Des 2024) menunjukkan garis Pantai Manikin mengalami erosi rata-rata 6,21 m dan akresi rata-rata 1,10 m.
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The Manikin River flows empties into the northern part of Kupang Regency, East Nusa Tenggara. In the Manikin River estuary and surrounding areas, there are settlements, rice fields, plantations, fishing activities, and so on. The Manikin River estuary is a vital area that connects the river flow with the sea, and affects coastal ecosystems and human activities. This research aims to analyze sedimentation and erosion, as well as morphological changes in the estuary and beach as a result of these processes by considering the influence of river discharge, tides, and waves.
This study adopts the Delft3D numerical modeling approach to simulate the influence of river and ocean waves in inducing the sediment transport process. Sediment data was obtained from direct sampling in the field which was then tested in the laboratory to obtain bed load (d50) and suspended load concentration. Meanwhile, discharge data was obtained from automatic water level data converted into river discharge data. Ocean waves were modeled using the SWAN spectral wave model using wave height and period analysis data from ECMWF ERA 5-Reanalysis. The model was carried out with a combination of currents and waves (flow coupling wave), and a current model without waves to see the influence of currents and waves in the sediment transport process. Modeling in four seasons, namely the west (wet) season, west-east season transition, east (dry) season, and east-west season transition to see the level of erosion and sedimentation that occurs in different seasons.
The results showed that the process of erosion and sedimentation generally occurs in the estuary and coastal areas with the influence of ocean waves being more dominant. The west season erosion and sedimentation occurs by the influence of high waves and increased discharge which is indicated by erosion and sedimentation along the coast and estuary area with an erosion thickness of 0.10 - 0.60 m sedimentation 0.10 -0.50 m. Total sediment transport in the wet season ranges from 0.00001 - 0.6550 kg/s/m. River flow and tidal processes generally have more influence on erosion and sedimentation processes in river areas. In the east season erosion and sedimentation are lower than the west season which is only influenced by waves and tidal backflow with erosion thickness of 0.10 - 0.40 and sedimentation of 0.10 - 0.40m. Total sediment transport in the season is below 0.05 kg/m/s. The small river discharge during the dry season shows the more dominant influence of ocean waves during the sediment transport process that occurs in the east season, although the wave height is relatively lower than the wave height in the west season. The shoreline changes during the 185-day modeling (01 Jun-02 Dec 2024) showed that the Manikin Beach line experienced an average erosion of 6.21m and an average accretion of 1.10m.

Item Type:	Thesis (Masters)
Uncontrolled Keywords:	Sedimen, Morfologi, Muara Sungai, garis pantai, debit sungai, pasang surut, gelombang, Delft3D Sediment, Morphology, River Estuary, Shoreline, River Discharge, Tides, Waves, Delft3D
Subjects:	T Technology > TC Hydraulic engineering. Ocean engineering > TC175.2 Sediment transport
Divisions:	Faculty of Civil Engineering and Planning > Civil Engineering > 22101-(S2) Master Thesis
Depositing User:	Alexandro Timotius Kolo
Date Deposited:	25 Jul 2025 04:44
Last Modified:	25 Jul 2025 04:44
URI:	http://repository.its.ac.id/id/eprint/121770

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