Perencanaan Pengendalian Banjir pada DAS Klagison Hilir Kota Sorong

Hidayah, Shofiatul (2025) Perencanaan Pengendalian Banjir pada DAS Klagison Hilir Kota Sorong. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Sungai Klagison merupakan salah satu sungai utama di Kota Sorong, Papua Barat, yang melintasi kawasan padat penduduk. Perkembangan wilayah yang pesat, alih fungsi lahan, dan kondisi hulu yang gundul akibat penambangan telah meningkatkan aliran permukaan dan sedimentasi sungai. Hal ini menyebabkan kapasitas aliran menurun dan risiko banjir meningkat, terutama di wilayah hilir. Tingginya pasang laut juga memicu fenomena backwater yang memperparah genangan. Pada 26 Agustus 2024, banjir besar menggenangi tujuh distrik dengan ketinggian air mencapai 60 cm. Untuk mengendalikan banjir di DAS Klagison, dilakukan perencanaan teknis. Curah hujan rencana dihitung dengan metode Gumbel periode ulang 10 tahun, sementara debit banjir dihitung menggunakan Hidrograf Satuan Sintetis Nakayasu. Debit maksimum tercatat sebesar 188,61 m³/s. Analisis kapasitas sungai dilakukan menggunakan HEC-RAS dengan pendekatan aliran seragam serta mempertimbangkan backwater dari pasang laut. Hasil simulasi menunjukkan bahwa penampang sungai eksisting tidak mampu mengalirkan debit rencana dengan periode ulang 25 tahun. Backwater menyebabkan kenaikan muka air hingga beberapa kilometer ke hulu. Sebagai solusi, dilakukan normalisasi sungai, pembangunan tanggul, dan pemasangan sheet pile. Di STA 0+000, penampang dirancang dengan lebar dasar 80 meter, kedalaman 2 meter, dan tinggi jagaan 0,6 meter. Pada STA 3+825, digunakan sheet pile 12 meter dengan kedalaman 2,8 meter. Rencana ini mampu menurunkan muka air banjir rata-rata 44,54% dari kondisi eksisting.
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The Klagison River is one of the main rivers in Sorong City, West Papua Province, flowing through densely populated areas. Rapid urban development, land-use changes, and deforestation in the upstream areas due to mining have increased surface runoff and sedimentation in the river. This has reduced the river's flow capacity and heightened flood risks, particularly in downstream regions. High tidal seawater levels also contribute to backwater effects in the river. On August 26th 2024, a major flood occurred, inundating seven districts with water levels reaching 60 cm. Therefore, technical planning for flood control in the Klagison Watershed is essential. The design rainfall was calculated using the Gumbel method with a 10-year return period, while flood discharge was estimated using the Nakayasu Synthetic Unit Hydrograph method. The peak discharge reached 188,61 m³/s. River capacity analysis was conducted using HEC-RAS under uniform flow conditions, considering the backwater effect from tidal seawater at the river mouth. The simulation results showed that the existing cross-section could not handle the 25 year return period design discharge, compounded by backwater effects raising water levels several kilometers upstream. As a solution, a new cross-section was designed through river normalization, embankment construction, and sheet pile installation. At STA 0+000, the cross-section was designed with a base width of 80 meters, a depth of 2 meters, and a freeboard of 0,6 meters. At STA 3+825, a 12-meter-long sheet pile with a depth of 2,8 meters was used to accommodate a discharge of 315,12 m³/s. The average flood water level reduction ranged from 44,54% from excisting condition. All river segments were designed to safely convey the design discharge.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Banjir, DAS Klagison, Normalisasi Sungai, Perencanaan Sheet Pile, Perencanaan Tanggul, Embankment, Flood, Klagison Watershed, Normalization, Sheet Pile
Subjects:	T Technology > TC Hydraulic engineering. Ocean engineering > TC530 Flood control
Divisions:	Faculty of Civil Engineering and Planning > Civil Engineering
Depositing User:	Shofiatul Hidayah
Date Deposited:	25 Jul 2025 02:40
Last Modified:	25 Jul 2025 02:40
URI:	http://repository.its.ac.id/id/eprint/121292

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