Pemodelan Numerik Genangan Banjir Akibat Keruntuhan Bendungan

Nadida, Zafira (2020) Pemodelan Numerik Genangan Banjir Akibat Keruntuhan Bendungan. Masters thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Pembangunan bendungan merupakan upaya yang dilakukan manusia untuk mengendalikan ketersediaan air di darat. Di sisi lain, adanya bendungan menyimpan resiko bencana yang besar jika terjadi keruntuhan bendungan. Tampungan air dari bendungan dapat mengalir dengan kecepatan tinggi sehingga memiliki daya hancur yang dapat menyebabkan kerusakan di daerah hilir hingga adanya korban jiwa. Salah satu upaya mitigasi menghadapi keruntuhan bendungan adalah dengan analisis resiko keruntuhan bendungan. Tesis ini meneliti dampak keruntuhan bendungan terhadap luas persebaran banjir. Penelitian ini mengambil objek Bendungan Way Sekampung, yang terletak di Kabupaten Pringsewu Lampung. Faktor pemicu keruntuhan bendungan yang dianalisis dalam penelitian ini disebabkan oleh piping dan overtopping, yang merupakan kasus terbanyak pada keruntuhan bendungan. Piping diteliti pada tiga titik tubuh bendungan yaitu berada di bagian atas, tengah dan bawah. Overtopping diteliti dengan melakukan simulasi debit PMF dengan asumsi pintu pelimpah tidak difungsikan. Simulasi keruntuhan bendungan menggunakan gabungan model 1D dan 2D pada aplikasi HEC-RAS. Input model terdiri dari Digital Elevation Model (DEM) yang digunakan untuk proses peniruan geometri sungai dan bendungan. Semua skenario akan menggunakan input Probable Maximum Flood (PMF). Data DEM didapatkan dari DEMNAS dengan skala 1:50.000. Debit PMF dihitung menggunakan data Curah Hujan selama 10 tahun dan data flood routing PMF Bendungan Batutegi. Hasil analisis keruntuhan bendungan menunjukkan luas genangan banjir terbesar disebabkan piping pada elevasi 120 yaitu seluas 43,17 km2, sedangkan kecepatan maksimum terjadi pada skenario Piping +120 yaitu sebesar 9,71 m/det. ============================================================================================================== Dam construction is an effort made by humans to control water availability on land. On the other hand, the existence of a dam saves a huge risk of disaster in the event of a dam failure. The water reservoir from the dam can flow at high speed, so that it has a destructive force that can cause damage in the downstream area as well as casualties. One of the mitigation efforts to deal with dam failure is by analyzing the risk of dam failure. This thesis examines the impact of dam failure on the extent of flood distribution. This study took the object of the Way Sekampung Dam located in Pringsewu Regency, Lampung. The trigger factors for dam failure analyzed in this study were caused by piping and overtopping, which were the most common cases of dam failure. Piping was examined at three points of the dam's body, namely at the top, middle and bottom. Overtopping was investigated by simulating PMF discharge with the assumption that the overflow gate was not functioning. The dam failure simulation used a combination of 1D and 2D models in the HEC-RAS application. The input model consisted of the Digital Elevation Model (DEM) which was used to simulate the geometry of rivers and dams. All scenarios used Probable Maximum Flood (PMF) input. DEM data were obtained from DEMNAS on a scale of 1: 50,000. PMF discharge was calculated using rainfall data for 10 years and flood routing data for the PMF of Batutegi Dam. The results of the dam failure analysis showed that the largest flood inundation area was due to piping at an elevation of 120, namely 43.17 km2, while the maximum velocity occurred in the Piping +120 scenario, which was 9.71 m/sec.

Item Type: Thesis (Masters)
Uncontrolled Keywords: piping, overtopping, floood innundation, Way Sekampung Dam, piping, overtopping, genangan banjir, bendungan way sekampung
Subjects: T Technology > TC Hydraulic engineering. Ocean engineering > TC167 Dams, reservoirs
Divisions: Faculty of Civil, Environmental, and Geo Engineering > Civil Engineering > 22101-(S2) Master Theses
Depositing User: Zafira Nadida
Date Deposited: 26 Aug 2020 02:34
Last Modified: 26 Aug 2020 02:34
URI: https://repository.its.ac.id/id/eprint/80800

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