Studi Pengendalian Banjir Pada Daerah Aliran Sungai Kali Lamong

Saputra, Bagas Maulana (2025) Studi Pengendalian Banjir Pada Daerah Aliran Sungai Kali Lamong. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Kali Lamong merupakan salah satu sungai utama di Jawa Timur yang selalu mengalami banjir tahunan, terutama pada wilayah hilir yang meliputi Kecamatan Cerme, Benjeng, Menganti dan Balongpanggang. Proyek akhir ini bertujuan untuk menganalisis pengendalian banjir pada segmen outlet DAS hulu hingga hilir melalui pendekatan normalisasi sungai. Perhitungan debit banjir rencana yang digunakan dalam studi ini menggunakan HSS Nakayasu pada DAS Hulu dan HSS SCS pada masing-masing SubDAS dengan kala ulang 25 tahun. Selanjutnya, pemodelan analisis hidraulika dilakukan menggunakan perangkat lunak HEC-RAS 2D dengan mempertimbangkan geomteri penampang eksisting sungai dan pengaruh pasang surut. Pada DAS Hulu Kali Lamong didapatkan debit sebesar 306.735 m³/s. Sementara itu, masing-masing SubDAS memiliki debit puncak berbeda, antara lain SubDAS Benowo sebesar 123,976 m³/s, Menganti sebesar 49,688 m³/s, Prambangan sebesar 50,324 m³/s, Jono sebesar 24,973 m³/s, Menganti II sebesar 208.981 m³/s, dan Iker-Iker sebesar 168.468 m³/s. Hasil simulasi menunjukkan bahwa kondisi eksisting sungai tidak mampu menampung debit banjir, sehingga mengakibatkan luapan pada beberapa titik penampang, terutama pada bagian hilir, simulasi juga mempertimbangkan kondisi pasang surut pada bagian hilir dengan pasang maksimum1.36 meter. Kondisi ini menyebabkan terjadinya genangan yang meluas di wilayah sekitar alur sungai. Penanganan banjir pada DAS Kali Lamong dilakukan dengan normalisasi dilakukan pada STA 06 - 600 menggunakan penampang majemuk dengan variasi lebar dasar 10 m, 15 meter, 20 meter, 25 meter, dan 30 meter, serta lebar dataran banjir 26 sampai 46 m, kedalaman disesuaikan, dan kemiringan lereng 1:2. Hasil analisis dengan pemodelan menunjukkan bahwa strategi normalisasi sungai mampu menurunkan risiko banjir secara signifikan terhadap luas genangan. Luas genangan eksisting mencapai 451.794 hektar setelah dilakukannya normalisasi, luas genangan menjadi 157.164 hektar dengan demikian, terjadi reduksi genangan sebesar 65,21%. Normalisasi sungai dapat menjadi model implementatif bagi pengendalian banjir di wilayah DAS Kali Lamong yang mengalami tekanan banjir akibat keterbatasan alur sungai.
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Kali Lamong is one of the major rivers in East Java that frequently experiences annual flooding, particularly in the downstream areas, including the subdistricts of Cerme, Benjeng, Menganti, and Balongpanggang. This final project aims to analyze flood control along the outlet segment of the upstream watershed to the downstream using a river normalization approach. The design flood discharge in this study was calculated using the Nakayasu Unit Hydrograph (UH) for the upstream watershed and the SCS UH for each sub-watershed, based on a 25-year return period. Hydraulic analysis modeling was conducted using HEC-RAS 2D software, incorporating the existing river cross-sectional geometry and the influence of tidal conditions. The peak discharge from the upstream watershed of Kali Lamong was found to be 306.735 m³/s, while each sub-watershed produced varying peak discharges: Benowo Sub-watershed at 123.976 m³/s, Menganti at 49.688 m³/s, Prambangan at 50.324 m³/s, Jono at 24.973 m³/s, Menganti II at 208.981 m³/s, and Iker-Iker at 168.468 m³/s. Simulation results show that the existing river condition is incapable of accommodating the flood discharge, leading to overflow at several cross-sections, particularly in the downstream areas. The simulation also considered tidal conditions in the lower reaches, with a maximum tide of 1.36 meters. This situation causes widespread inundation around the river corridor. Flood management in the Kali Lamong watershed was addressed through river normalization in the critical segment STA 06–600, using compound cross-sections with bottom widths of 10 m, 15 m, 20 m, 25 m, and 30 m, floodplain widths ranging from 26 to 46 meters, slope ratio of 1:2, and depths adjusted to the existing terrain. The analysis results indicate that the normalization strategy significantly reduces flood risk by decreasing the inundation area. The existing inundated area of 451.794 hectares was reduced to 157.164 hectares after normalization, resulting in a 65.21% reduction. River normalization can serve as an implementable model for flood control in the Kali Lamong watershed, which suffers from flooding due to the limited capacity of the river channel.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Kali Lamong, Pengendalian Banjir, Normalisasi Sungai,Pemodelan Hidraulik, Flood Control, River Normalization, Hydraulic Modelling,
Subjects:	T Technology > TC Hydraulic engineering. Ocean engineering > TC530 Flood control
Divisions:	Faculty of Vocational > Civil Infrastructure Engineering (D4)
Depositing User:	Bagas Maulana Saputra
Date Deposited:	04 Aug 2025 03:31
Last Modified:	04 Aug 2025 03:31
URI:	http://repository.its.ac.id/id/eprint/126492

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