Studi Alternatif Penggunaan Data Hujan Satelit GPM dalam Analisis Banjir pada Sungai Bendokrosok di Desa Maron, Kabupaten Kediri

Mahendra, Yusif Fikri Ihza (2026) Studi Alternatif Penggunaan Data Hujan Satelit GPM dalam Analisis Banjir pada Sungai Bendokrosok di Desa Maron, Kabupaten Kediri. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Kejadian banjir pada 22 Desember 2024 yang merendam koridor Jalan Raya Nganjuk–Kediri, khususnya di sekitar Desa Maron yang dipengaruhi aliran Sungai Bendokrosok, menunjukkan pentingnya analisis banjir yang andal pada DAS berukuran kecil. Di sisi lain, keterbatasan sebaran dan kontinuitas data stasiun hujan di Indonesia mendorong perlunya studi pemanfaatan data hujan satelit sebagai alternatif sumber data analisis hidrologi. Penelitian ini bertujuan mengevaluasi keandalan data hujan satelit GPM-IMERG Final Run sebagai alternatif untuk analisis banjir pada DAS Bendokrosok melalui pembandingan terhadap curah hujan wilayah berbasis stasiun serta penerapan koreksi bias. Data hujan wilayah stasiun (Poligon Thiessen) dan GPM-IMERG (area-averaged) dievaluasi pada skala harian selama 2000-2025. Hasil evaluasi menunjukkan bahwa data GPM-IMERG mentah memiliki kesamaan pola distribusi (r = 0,9979), namun memiliki bias deviasi absolut yang tinggi pada kejadian ekstrem (overestimation dan underestimation) sehingga wajib dikoreksi. Penerapan koreksi bias metode Quantile Mapping berbasis Cumulative Distribution Function (CDF) terbukti sangat efektif mereduksi galat statistik GPM-IMERG tanpa indikasi overfitting, ditandai dengan penurunan RMSE menjadi 0,0005 dan MAE menjadi 0,0000. Analisis frekuensi ekstrem pada data terkoreksi menghasilkan curah hujan rencana kala ulang 25 tahun sebesar 112,25 mm. Melalui pemodelan Hidrograf Satuan Sintetis (HSS) Nakayasu, diperoleh debit banjir puncak rencana sebesar 49,14 m³/s. Pemodelan hidrolika HEC-RAS 1D (steady flow) mengonfirmasi bahwa penampang terkini Sungai Bendokrosok tidak mampu mengalirkan debit tersebut secara aman, memicu limpasan (overtopping) setinggi 1 meter pada segmen kritis antara STA 10+300 hingga STA 9+920. Sebagai alternatif pengendalian banjir, dirumuskan skenario normalisasi penampang dan pemasangan sheet pile yang terbukti efektif menampung debit rencana kala ulang 25 tahun dengan menurunkan elevasi muka air banjir sebesar 1 meter.
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The flood event on December 22, 2024, which inundated the Nganjuk–Kediri Highway corridor, around Maron Village affected by the flow of the Bendokrosok River, highlights the importance of reliable flood analysis in small-sized watersheds. On the other hand, the limited distribution and continuity of rainfall station data in Indonesia prompt the need for studies utilizing satellite rainfall data as an alternative source for hydrological analysis. This study aims to evaluate the reliability of GPM-IMERG satellite rainfall data as an alternative for flood analysis in the Bendokrosok Watershed by comparing it against station-based areal rainfall and applying bias correction. Station areal rainfall data (Thiessen Polygon) and GPM-IMERG data (area-averaged) were evaluated on a daily scale for the period of 2000–2025. The evaluation results show that the GPM-IMERG data shares a similar distribution pattern (r = 0.9979) but exhibits high absolute deviation biases in extreme events (overestimation and underestimation), thus requiring correction. The application of the Cumulative Distribution Function (CDF)-based Quantile Mapping bias correction method proved highly effective in reducing the error of GPM-IMERG without overfitting, marked by a reduction in RMSE to 0.0005 and MAE to 0.0000. Extreme frequency analysis on the corrected data yielded a 25-year return period design rainfall of 112.25 mm. Through the Nakayasu Synthetic Unit Hydrograph (SUH) modeling, a design peak flood discharge of 49.14 m³/s was obtained. The HEC-RAS 1D hydraulic modeling (steady flow) confirmed that the current cross-section of the Bendokrosok River is incapable of safely conveying this discharge, triggering an overtopping of 1 meter at the critical segment between STA 10+300 and STA 9+920. As a flood control alternative, scenarios of river channel normalization and sheet pile were formulated, which proved effective in accommodating the 25-year return period design discharge by lowering the flood water surface elevation by 1 meters.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	koreksi bias, GPM-IMERG, HEC-RAS, Nakayasu, quantile mapping, Bendokrosok, bias correction, GPM-IMERG, HEC-RAS, Nakayasu, quantile mapping, Bendokrosok
Subjects:	T Technology > TC Hydraulic engineering. Ocean engineering > TC530 Flood control T Technology > TD Environmental technology. Sanitary engineering > TD481 Water distribution systems
Divisions:	Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Civil Engineering > 22201-(S1) Undergraduate Thesis
Depositing User:	Yusif Fikri Ihza Mahendra
Date Deposited:	01 Aug 2026 06:00
Last Modified:	01 Aug 2026 06:00
URI:	http://repository.its.ac.id/id/eprint/138645

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