ANALISIS KONDISI EKSISTING PENAMPANG SUNGAI CISANGKUY HILIR MENGGUNAKAN HEC-RAS 4.1.0
Abstract
Abstrak: Banjir yang terjadi akibat meluapnya Sungai Cisangkuy Hilir mengakibatkan kerugian yang besar mencakup kerugian fisik maupun non fisik. Meluapnya Sungai Cisangkuy Hilir tersebut disebabkan karena sungai tidak mampu lagi menampung debit banjir yang terjadi. Makalah ini membahas mengenai analisis kondisi penampang eksisting Sungai Cisangkuy Hilir terhadap debit banjir rencana (periode ulang 20 tahun) menggunakan software HEC-RAS. Penelitian kali ini menggunakan HEC-RAS dari mulai pembuatan model tiruan Sungai Cisangkuy Hilir sampai simulasi aliran model tersebut. Berdasarkan hasil simulasi, ( steady flow analysis) menggunakan debit banjir rencana periode ulang 20 tahun (229, 27 m3/s) bahwa semua penampang mengalami banjir dan tidak memenuhi persyaratan tinggi jagaan (0.75 meter). Tinggi banjir tertinggi terdapat pada stasiun 17,4 yaitu mencapai 3,06 meter sedangkan tinggi banjir terendah terdapat pada stasiun 0 yaitu sebesar 0,03 meter. Banjir tersebut disebabkan karena tinggi sedimen yang mencapai tiga meter di sepanjang sungai yang membuat kapasitas penampang menjadi kecil. Sehingga dapat diambil kesimpulan bahwa Sungai Cisangkuy Hilir memerlukan upaya penanganan banjir khususnya dengan normalisasi penampang sungai.
Kata kunci: penampang, model, sedimen, simulasi, steady
Abstract: Floods caused by overflowing of the river downstream Cisangkuy cause large losses include loss of physical and non-physical. Cisangkuy River Downstream overflowing caused by the river no longer able to accommodate the flood discharge. This paper discusses the analysis of the existing conditions section Cisangkuy river downstream with discharge plan (20 year return period) using HEC-RAS software. This research using HEC-RAS ranging from artificial modeling Cisangkuy River downstream until flow simulation model. Based on simulation results, (steady flow analysis) using the flood discharge plan period of 20 years (229, 27 m3/s) that all the section was flooded and did not comply the freeboard (0.75 meters). The highest floods are on station 17.4, reaching 3.06 meters while the lowest was at station flood 0 is equal to 0.03 meters. The flood was caused by high sediment that reaches three meters along the river which makes a small cross-section capacity. So it can be concluded that the river downstream Cisangkuy require flood mitigation efforts in particular by normalizing the river section.
Keywords: cross section, models, sediment, simulation, steady
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