Pengendalian Banjir Pada Sungai Kolokoso

Laksono, Ramandika Kukuh (2026) Pengendalian Banjir Pada Sungai Kolokoso. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Kapasitas Sungai Kolokoso menurun hal ini di sebabkan perubahan tata guna lahan dan pertumbuhan penduduk serta tingginya intensistas hujan, sehingga Sungai Koloksoso tidak lagi mampu mengalirkan air dengan baik dan meningkatkan risiko banjir. Banjir yang terjadi pada Januari 2023 menimbulkan genangan setinggi 20–50 cm di beberapa desa, terutama Desa Kaliboto. Kondisi ini diperparah oleh tersumbatnya aliran sungai. Genangan banjir merendam lahan persawahan warga sehingga mengakibatkan kerusakan tanaman padi, gagal panen, dan kerugian ekonomi yang dirasakan langsung oleh petani sebagai sumber mata pencaharian utama masyarakat setempat. Tujuan penelitian ini untuk mengatasi permasalahan banjir di Sungai Kolokoso melalui beberapa tahapan analisis, yaitu melalui pengolahan data hujan historis, analisis frekuensi (Log-Pearson Type III/Gumbel), penghitungan curah hujan rencana (R25) dengan metode Thiessen, transformasi hujan menjadi hidrograf satuan (Synthetic Unit Hydrograph Nakayasu), analisis kondisi hidraulika sungai menggunakan program HEC-RAS, serta penentuan solusi yang tepat untuk pengendalian banjir dengan mempertimbangkan kondisi stabilitas lereng sungai. Hasil analisis menunjukkan debit banjir kala ulang 25 tahun pada Sub-DAS Kolokoso sebesar 647,76 m³/detik, setelah dilakukan analisa hidraulika dengan simulasi HEC-RAS menunjukkan hasil limpasan air setinggi 0,5 - 1 m di atas tanggul sungai. Analisis stabilitas lereng dengan GeoStudio juga menunjukkan nilai faktor keamanan (FS) tanpa perkuatan masih di bawah kriteria minimum SNI 8460:2017, dengan nilai terendah 1,353 pada STA 10+040. Sebagai solusi utama pengendalian banjir, dilakukan perubahan dimensi luas penampang sungai dari semula 109,74 m² menjadi 155,46 m², solusi ini meningkatkan kapasitas aliran sungai sebesar 41,6 % dari kondisi eksisting sehingga risiko banjir di kawasan hilir sungai berkurang secara signifikan. Serta sebagai solusi tambahan direncanakan perkuatan tambahan berupa shotcrete pada STA 9+720–11+140 guna meningkatkan FS dari 1,353 menjadi 1,516.
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The capacity of the Kolokoso River has decreased due to changes in land use, population growth, and high rainfall intensity, resulting in the river’s inability to drain water properly and increasing the risk of flooding. The flood that occurred in January 2023 caused water levels of 20–50 cm in several villages, particularly Kaliboto Village. This situation was exacerbated by blockages in the river’s flow. The floodwaters submerged residents’ rice fields, resulting in damage to rice crops, crop failure, and economic losses directly felt by farmers, who rely on rice farming as the primary source of livelihood for the local community. The objective of this study is to address the flooding issues in the Kolokoso River through several stages of analysis, namely the processing of historical rainfall data, frequency analysis (Log-Pearson Type III/Gumbel), calculation of design rainfall (R25) using the Thiessen method, transformation of rainfall into a unit hydrograph (Nakayasu Synthetic Unit Hydrograph), analysis of river hydraulic conditions using the HEC-RAS program, and determination of appropriate solutions for flood control while considering riverbank stability. The analysis results indicate a 25-year return period flood discharge in the Kolokoso Sub-Watershed of 647.76 m³/s; following hydraulic analysis using HEC-RAS simulation, the results show water overflows of 0.5–1 m above the river embankment. Slope stability analysis using GeoStudio also showed that the safety factor (FS) without reinforcement remained below the minimum criteria of SNI 8460:2017, with the lowest value of 1.353 at STA 10+040. As the primary flood control solution, the river cross-sectional area was increased from 109.74 m² to 155.46 m². This solution increases the river’s flow capacity by 41.6% compared to the existing conditions, thereby significantly reducing the risk of flooding in the downstream area. Additionally, as a supplementary measure, reinforced shotcrete is planned for the section at STA 9+720–11+140 to increase the FS from 1.353 to 1.516.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Debit banjir, HSS Nakayasu, HEC-RAS, Pengendalian banjir, Stabilitas lereng, Flood discharge, Nakayasu HSS, HEC-RAS, Flood control, Slope stability
Subjects:	T Technology > TC Hydraulic engineering. Ocean engineering > TC530 Flood control
Divisions:	Faculty of Vocational > 22301-Civil Infrastructure Engineering (D4)
Depositing User:	Ramandika Kukuh Laksono
Date Deposited:	03 Aug 2026 08:54
Last Modified:	03 Aug 2026 08:54
URI:	http://repository.its.ac.id/id/eprint/142356

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