Penilaian Risiko Banjir Berdasarkan Model Numerik 2D pada DAS Buntung Kabupaten Sidoarjo

Nanda, Nur Izzah Elsa (2026) Penilaian Risiko Banjir Berdasarkan Model Numerik 2D pada DAS Buntung Kabupaten Sidoarjo. Masters thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Banjir merupakan bencana alam dengan frekuensi kejadian tertinggi di Indonesia, mencakup 55,07% dari total bencana nasional. Kabupaten Sidoarjo, khususnya Kecamatan Waru, merupakan wilayah rawan banjir akibat luapan Sungai Buntung. Banjir akibat luapan Sungai Buntung pada tanggal 9 Maret 2025 menyebabkan dua desa yaitu Desa Ketegan dan Kedungturi di Kecamatan Taman tergenang setinggi 30-50 sentimeter dan pada tanggal 16 Maret 2025 terjadi genangan selama dua hari dengan ketinggian setinggi 30 – 40 sentimeter di Kecamatan Waru. Kawasan ini memiliki tingkat perkembangan aktivitas permukiman, industri, dan transportasi yang tinggi, mengakibatkan berkurangnya daerah resapan air. Tingginya curah hujan, pasang surut air laut, serta penyempitan dan penyumbatan aliran di hilir sungai turut memperburuk kondisi banjir di wilayah ini.
Penelitian ini bertujuan untuk menilai risiko banjir di DAS Buntung dengan menganalisis debit banjir dengan periode ulang tertentu, memodelkan sebaran aliran dan genangan, serta menilai hubungan antara debit banjir dengan luas, kedalaman, dan durasi genangan. Penelitian juga bertujuan untuk menyusun peta risiko banjir dan merumuskan strategi mitigasi yang efektif dalam penanganan banjir di wilayah studi.
Metode yang digunakan dalam penelitian ini meliputi pemodelan hidrologi menggunakan model hujan-debit untuk menghitung debit banjir dan pemodelan hidraulik dua dimensi untuk mensimulasikan penyebaran aliran dan genangan. Parameter yang digunakan meliputi data hujan, topografi, penggunaan lahan, serta karakteristik DAS Buntung. Penilaian risiko dilakukan dengan mengkaji kedalaman, luas, dan durasi genangan, yang diklasifikasikan dalam tingkat risiko tertentu.
Hasil penelitian diperoleh bahwa pada periode ulang Q25 debit sebesar 200,263 m3/detik, menghasilkan genangan seluas 46,162 km2, dengan kedalaman genangan rata-rata 0,281 m. Nilai risiko banjir eksisting 0,520 didominasi tingkat kategori sedang. Reduksi genangan banjir terbesar yaitu pada skenario kombinasi antara normalisasi, pompa, bozem, dan tanggul sungai mampu mereduksi nilai risiko genangan 31,03% menjadi risiko rendah.
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Flooding is the most frequent natural disaster in Indonesia, accounting for 55.07% of all national disasters. Sidoarjo Regency, particularly Waru District, is highly prone to flooding due to overflow from the Buntung River. On March 9, 2025, flooding caused by the Buntung River overflow inundated two villages—Ketegan and Kedungturi in Taman District—with water depths ranging from 30 to 50 centimeters. Subsequently, on March 16, 2025, inundation occurred again in Waru District, lasting two days with water levels reaching 30 to 40 centimeters. This area experiences rapid growth in residential, industrial, and transportation activities, which has significantly reduced water infiltration areas. High rainfall intensity, tidal influences, and narrowing or blockage in the downstream river sections further exacerbate flooding conditions.
This study aims to assess flood risk in the Buntung River Basin by analyzing flood discharges for specific return periods, modeling flow and inundation distribution, and evaluating the relationship between flood discharge and the extent, depth, and duration of inundation. The research also aims to develop a flood risk map and formulate effective mitigation strategies for managing floods in the study area.
The methodology involves hydrological modeling using a rainfall-runoff approach to estimate flood discharges, and two-dimensional hydraulic modeling to simulate the flow and inundation spread. Parameters used include rainfall data, topography, land use, and watershed characteristics of Buntung Basin. Flood risk assessment is conducted by analyzing flood depth, extent, and duration, which are classified into specific risk levels.
The results showed that the 25-year return period (Q25) generated a peak discharge of 200.263 m³/s, resulting in a flood inundation area of 46.162 km² with an average inundation depth of 0.281 m. Under the existing condition, the average flood risk index was 0.520, which was predominantly classified as a moderate risk level. The greatest reduction in flood inundation risk was achieved by the combined mitigation scenario consisting of river normalization, pumping stations, a retention pond (bozem), and river levees, which reduced the flood risk index by 31.03%, shifting the dominant flood risk classification to the low-risk category.

Item Type:	Thesis (Masters)
Uncontrolled Keywords:	Risiko Banjir, Hujan-Debit, HEC-RAS 2D, DAS Buntung, Flood Risk, Rainfall-Runoff, HEC-RAS 2D, Buntung Watershed
Subjects:	T Technology > T Technology (General) > T174.5 Technology--Risk assessment. T Technology > TC Hydraulic engineering. Ocean engineering > TC530 Flood control T Technology > TE Highway engineering. Roads and pavements > TE215 Drainage
Divisions:	Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Civil Engineering > 22101-(S2) Master Thesis
Depositing User:	Nur Izzah Elsa Nanda
Date Deposited:	29 Jul 2026 03:15
Last Modified:	29 Jul 2026 03:15
URI:	http://repository.its.ac.id/id/eprint/138848

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