Analisis Peta Risiko Banjir Akibat Keruntuhan Bendungan Jragung Menggunakan Hec-Ras 2d

Salam, Ahmad Firdaus (2023) Analisis Peta Risiko Banjir Akibat Keruntuhan Bendungan Jragung Menggunakan Hec-Ras 2d. Diploma thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Bendungan memiliki banyak manfaat bagi masyarakat yaitu sebagai penyimpan air, pencegah banjir, penyediaan air irigasi, objek wisata, penyediaan energi pembangkit listrik tenaga air (PLTA) dan lainnya. Namun, di balik banyaknya manfaat yang dimiliki bendungan, tersembunyi bahaya bagi kehidupan masyarakat di hilir bendungan. Salah satu ancaman yang ditimbulkan ketika adanya bendungan adalah keruntuhan bendungan, keruntuhan bendungan menyebabkan banjir dahsyat di hilir bendungan. Mempertimbangkan besarnya ancaman keruntuhan bendungan, diperlukan pengkajian risiko sebagai acuan dalam penyusunan dokumen rencana tindak darurat.
Pada proyek akhir ini penulis mengambil objek Bendungan Jragung yang berlokasi di Kabupaten Semarang, Jawa Tengah. Sebelum melakukan simulasi keruntuhan bendungan, dilakukan analisis rembesan menggunakan GeoStudio SEEP/W dan analisis angka keamanan terhadap piping. Simulasi keruntuhan bendungan pada proyek akhir ini menggunakan HEC-RAS 6.3.1. Simulasi dilakukan dengan skenario piping pada tiga kondisi, yaitu PMF, debit banjir 1000 tahun, dan kondisi muka air normal. Analisis spasial dampak keruntuhan bendungan dilakukan menggunakan ArcGIS, di mana dampak keruntuhan digunakan sebagai dasar pemetaan risiko. Berdasarkan hasil perhitungan banjir rancangan, didapatkan debit PMF sebesar 1177,995 m3/detik. Penelusuran banjir pada saat PMF didapatkan bahwa elevasi muka air PMF tidak melewati puncak bendungan. Simulasi keruntuhan bendungan dilakukan dengan skenario piping saja, karena tidak terjadi overtopping. Simulasi keruntuhan bendungan yang disebabkan piping saat PMF memiliki dampak terbesar dengan luas banjir 16747,85 hektare dan ketinggian banjir maksimum sebesar 32,61 meter. Daerah yang terdampak kerusakan yang luas akibat keruntuhan Bendungan Jragung sebanyak 34 desa, meliputi 22 desa di Kabupaten Demak dan 12 desa di Kabupaten Grobogan. Total daerah berisiko adalah 15738,27 hektare dengan kelas risiko tinggi mendominasi 52% dari daerah berisiko, kemudian diikuti oleh kelas risiko sedang 25% dari daerah berisiko dan kelas risiko rendah 22% dari daerah berisiko. Desa Padang dan Kebonagung merupakan lokasi berisiko tinggi karena kerusakan yang luas dan dekat dengan bendungan.
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Dams have many benefits for the community, namely as water storage, flood prevention, irrigation water supply, tourist attractions, hydroelectric power plant (PLTA) energy supply and others. However, behind the many benefits that the dam has, hidden dangers to the lives of people downstream of the dam. One of the threats posed when there is a dam is the collapse of the dam, the collapse of the dam causes a devastating flood downstream of the dam. Considering the magnitude of the threat of dam collapse, a risk assessment is needed as a reference in the preparation of emergency action plan documents.
In this final project, the author took the object of Jragung Dam located in Semarang Regency, Central Java. Before simulating dam collapse, seepage analysis was carried out using GeoStudio SEEP/W and piping safety figure analysis. Simulated dam collapse in this final project using HEC-RAS 6.3.1. The simulation was carried out with piping scenarios under three conditions, namely PMF, 1000-year flood discharge, and normal water table conditions. Spatial analysis of dam collapse impacts is performed using ArcGIS, where the impact of the collapse is used as the basis for risk mapping.
Based on the results of the design flood calculation, a PMF discharge of 1177,995 m3/s was obtained. Flood routing at the time of PMF found that the PMF water level elevation did not pass the top of the dam. The dam collapse simulation was carried out with piping scenarios only, because overtopping did not occur. Simulated dam collapse caused by piping during PMF had the largest impact with a flood area of 16747,85 hectares and a maximum flood height of 32,61 meters. The area affected by extensive damage due to the collapse of the Jragung Dam was 34 villages, including 22 villages in Demak Regency and 12 villages in Grobogan Regency. The total risk area is 15738,27 hectares with high risk class dominating 52% of the risk area, followed by medium risk class 25% of the risk area and low risk class 22% of the risk area. The villages of Padang and Kebonagung are high-risk locations due to extensive damage and close proximity to dams.

Item Type:	Thesis (Diploma)
Uncontrolled Keywords:	Banjir, HEC-RAS, Keruntuhan Bendungan, Peta Risiko Flood, HEC-RAS, Dam Break, Risk Map
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) > TA169.5 Failure analysis T Technology > TA Engineering (General). Civil engineering (General) > TA590 Topographical surveying T Technology > TC Hydraulic engineering. Ocean engineering > TC167 Dams, reservoirs
Divisions:	Faculty of Vocational > Civil Infrastructure Engineering (D4)
Depositing User:	Ahmad Firdaus Salam
Date Deposited:	10 Aug 2023 08:57
Last Modified:	10 Aug 2023 08:57
URI:	http://repository.its.ac.id/id/eprint/103369

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