Pengaruh Distribusi Hujan Rancangan Terhadap Luas Dan Kedalaman Genangan Pada Sistem Drainase Kalibokor Kota Surabaya

Yelisa, Aulia Putri (2026) Pengaruh Distribusi Hujan Rancangan Terhadap Luas Dan Kedalaman Genangan Pada Sistem Drainase Kalibokor Kota Surabaya. Masters thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Kota Surabaya menghadapi tantangan besar dalam pengelolaan sistem drainase, terutama di kawasan Kalibokor yang menjadi salah satu wilayah rawan genangan saat musim hujan. Salah satu faktor yang memengaruhi genangan namun belum banyak dikaji adalah distribusi hujan temporal, yaitu pola perubahan intensitas hujan selama kejadian hujan berlangsung. Perbedaan pola distribusi hujan dapat menghasilkan kondisi genangan yang berbeda meskipun total curah hujan yang terjadi sama. Oleh karena itu, kajian mengenai pengaruh distribusi hujan temporal terhadap karakteristik genangan diperlukan untuk mendukung perencanaan sistem drainase yang lebih adaptif terhadap variasi karakteristik hujan. Penelitian ini bertujuan untuk menganalisis distribusi curah hujan temporal, membangun model hidrolika aliran dua dimensi (2D) yang representatif, serta mensimulasikan pengaruh variasi durasi hujan dan posisi waktu puncak hujan (time of peak) terhadap luas dan kedalaman genangan pada Sistem Drainase Kalibokor, Surabaya Timur. Pemodelan dilakukan menggunakan HEC-RAS 2D dengan metode Rain on Grid. Model dikalibrasi menggunakan data genangan pada 21 titik pengamatan saat kejadian hujan 31 Januari 2020, kemudian digunakan untuk mensimulasikan 21 skenario hujan periode ulang 10 tahun dengan variasi durasi hujan 1–6 jam dan tiga distribusi waktu puncak hujan, yaitu early peak (Mononobe), middle peak (Alternating Block Method), dan late peak (Mononobe modifikasi). Hasil penelitian menunjukkan bahwa distribusi hujan temporal di Sistem Drainase Kalibokor cenderung berpola early peak dan mendekati distribusi Mononobe. Model hidrolika 2D yang dikembangkan menunjukkan kesesuaian yang baik terhadap kondisi genangan aktual sehingga dinilai representatif untuk simulasi. Variasi distribusi hujan temporal terbukti memengaruhi luas dan kedalaman genangan. Luas genangan menurun dari 3,895 km² pada hujan berdurasi 1 jam menjadi 3,318 km² pada hujan berdurasi 6 jam atau berkurang sebesar 14,814%. Pada variasi posisi waktu puncak hujan, semakin akhir waktu puncak hujan terjadi, semakin besar luas dan kedalaman genangan yang terbentuk. Distribusi late peak menghasilkan luas dan kedalaman genangan terbesar, distribusi middle peak menghasilkan kondisi di antara keduanya, sedangkan distribusi early peak menghasilkan genangan terkecil. Selain itu, distribusi late peak menghasilkan kedalaman genangan lebih besar dibandingkan early peak pada 92,5% kombinasi titik dan durasi pengamatan, dengan selisih luas genangan maksimum mencapai 0,287 km² (8,65%).
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Surabaya faces major challenges in managing the drainage system, especially in the Kalibokor area, which is prone to inundation during the rainy season. The temporal rainfall distribution, which describes the variation in rainfall intensity throughout a rainfall event, is a factor that may influence the characteristics of inundation, but it has received limited attention. Different temporal rainfall patterns may produce different inundation characteristics even under the same total rainfall. Understanding the influence of temporal rainfall distribution on inundation characteristics is essential for developing more adaptive drainage systems to varying rainfall patterns. This study aims to analyze the temporal rainfall distribution, develop a representative two-dimensional (2D) hydraulic model, and evaluate the effects of rainfall duration and peak timing (time of peak) on inundation extent and depth in the Kalibokor Drainage System, East Surabaya. The hydraulic model was developed using HEC-RAS 2D with the ROG approach. The model was calibrated using inundation observations at 21 monitoring points during the rainfall event on January 31, 2020. The calibrated model was then applied to simulate 21 design rainfall scenarios with a 10-year return period, consisting of rainfall durations of 1–6 h and three temporal rainfall distributions: early peak (Mononobe), middle peak (Alternating Block Method), and late peak (Modified Mononobe). The results indicate that the temporal rainfall distribution of the Kalibokor drainage system is characterized by an early peak pattern and closely follows the Mononobe distribution. The developed 2D hydraulic model showed good agreement with the observed inundation conditions and was therefore considered suitable for simulation. Temporal rainfall distribution significantly affected inundation extent and depth. The inundation extent decreased from 3.895 km² for a 1-h rainfall duration to 3.318 km² for a 6-h rainfall duration, representing a 14.814% reduction. Regarding peak timing, later peak occurrences resulted in greater extent and depth of inundation. The largest inundation was generated by the late peak distribution, the middle peak distribution produced intermediate conditions, and the smallest inundation was produced by the early peak distribution. Furthermore, the late peak distribution produced greater inundation depths than the early peak distribution in 92.5% of all point-duration combinations, with a maximum difference in inundation extent of 0.287 km² (8.65%).

Item Type:	Thesis (Masters)
Uncontrolled Keywords:	distribusi hujan, HEC-RAS 2D, rain on grid, Sistem Drainase Kalibokor, time of peak, HEC-RAS 2D, Kalibokor Drainage System, rain on grid, temporal rainfall distribution,time of peak
Subjects:	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:	Aulia Putri Yelisa
Date Deposited:	29 Jul 2026 01:40
Last Modified:	29 Jul 2026 01:40
URI:	http://repository.its.ac.id/id/eprint/139351

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