ANALISA KERUNTUHAN BENDUNGAN KEUREUTO DENGAN MENGGUNAKAN BANTUAN SOFTWARE ZHONG XING HY21

Roid Ghozi, Heri Suprijanto

Abstract


ABSTRAK: Keruntuhan bendungan yang sering terjadi diakibatkan oleh overtopping dan piping, kerutuhan tersebut dapat mengakibatkan banjir yang  besar di hilirnya, sehingga perlu dilakukan analisa keruntuhan bendungan (Dam Break Analysis) serta simulasi keruntuhan bendungan (Dam Break Simulation). Setelah melakukan perhitungan uji kesesuaian, selanjutnya adalah menghitung debit banjir rencana menggunakan HSS Nakayasu, didapat debit Inflow Q100 sebesar 1039,817 m3/det, Q1000 sebesar 1360,967 m3/det PMF nya sebesar 2530,454 m3/det, setelah menghitung debit banjir rencana, selanjutnya adalah menghitung penelusuran banjir (flood routing) terhadap pelimpah berpintu dengan hasil: dengan kondisi pintu beroperasi adalah Outflow sebesar 389,15 m3/det pada elevasi 103,92 m ketika menggunakan Q100. Outflow sebesar 605,60 m3/det pada elevasi 104,63 m ketika menggunakan Q1000. Outflow sebesar 887,496 m3/det pada elevasi 106,72 m ketika menggunakan QPMF. Dengan Elevasi puncak bendungan berada pada elevasi +107,50 m. Hasil yang diperoleh dari software Zhong Xing HY21 berupa peta genangan banjir, waktu tiba, waktu puncak, kedalaman, kecepatan dan elevasi banjir. Kondisi yang digunakan adalah piping dengan kondisi muka air banjir dan overtopping. Sehingga diperoleh luas genangan untuk kondisi overtopping sebesar 125,2187 km2 sedangkan pada kondisi piping atas 124,3683 km2, piping tengah 124,2162 km2, piping bawah 124,4965 km2. Kemudian dilakukan perhitungan total kerugian pada 140 desa terdampak yang mencapai Rp. 383,489,826,728.

ABSTRACT: Dam break that often occur are caused by overtopping and piping, the fragility can result in very large floods in the downstream, so dam break analysis is needed and simulation of dam break is simulated. After calculating the suitability test, the next step is to calculate the planned flood discharge using Nakayasu HSS which obtained an Inflow Q100 discharge of 1039.817 m3/sec, Q1000 of 1360.967 m3/sec QPMF discharge of 2530.454 m3/sec, after counting planned flood discharge, the next step is to calculate flood routing of the spillway with door and the results: with the condition of the operating door the Outflow is 389.15 m3/sec at 103.92 m elevation when using Q100. The outflow was 605.60 m3/sec at 104.63 m elevation when using Q1000. The outflow was 887,496 m3/sec at an elevation of 106.72 m when using QPMF. With the top elevation of the dam at an elevation of +107.50 m. The results obtained from Zhong Xing HY21 software are flood inundation maps, arrival time, peak time, depth, speed and flood elevation. The conditions used are piping with flood water conditions and overtopping. So that the inundation area for overtopping conditions is 125.2187 km2 while in piping conditions above 124.3683 km2, the middle piping is 124.2162 km2, piping below 124.4965 km2. Then the last step after running the software is to calculate the analysis of the losses caused by the dam break of the Keureuto Dam in accordance with existing guidelines. So that after the calculation was made, the total losses in 140 impacted villages reached Rp. 383,489,826,728.


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