Analisis Keruntuhan Bendungan Telaga Pasir Kabupaten Magetan Melalui Simulasi HEC-RAS dan Berbasis InaSAFE
Authors: Siregar Jeremi Ishak , Dermawan Very , Sisinggih Dian 
Published: January 2023

Telaga Pasir Dam is one of Indonesia's natural lakes which provides irrigation water and tourist spot. Despite that, Telaga Pasir Dam is not free from the risk of a dam break along with the age of the dam. The purpose of this study is to determine the maximum flood discharge in the Telaga Pasir Dam catchment area, the flood inundation due to the collapse of Telaga Pasir Dam based on the HEC-RAS 5.0.7 simulation, to classify the hazard level of the collapse, and to estimate the economic losses caused by the collapse of the dam using InaSAFE. The analysis results show that the PMF discharge from Nakayasu method is 56,285 m3/sec. Which then, is used in HEC-RAS for several scenarios. The maximum area affected by the collapse of Telaga Pasir Dam is 14,496 km2 with a maximum flood height of 34.61 m. Based on the results of the flood distribution entered into the InaSAFE program, the collapse of Telaga Pasir Dam is categorized as a high-level flood hazard. The estimated economic loss caused by the collapse of the Telaga Pasir Dam is Rp. 154.225.241.802.
Bendungan Telaga Pasir yang berada pada Kabupaten Magetan adalah salah satu bendungan alam (telaga alami) yang terdapat di Indonesia. Bendungan Telaga Pasir berfungsi untuk penyediaan air irigasi dan sebagai tempat wisata. Selain fungsi tersebut, Bendungan Telaga Pasir juga tidak lepas dari resiko dari terjadinya sebuah keruntuhan bendungan seiring dengan usia bendungan yang semakin menua. Tujuan dari penelitian ini yaitu untuk mengerti besarnya debit banjir rancangan maksimum pada wilayah daerah tangkapan air Bendungan Telaga Pasir, mengetahui sebaran banjir akibat keruntuhan Bendungan Telaga Pasir berdasarkan simulasi HEC-RAS 5.0.7, mengetahui klasifikasi tingkat bahaya, dan estimasi kerugian ekonomi yang disebabkan keruntuhan Bendungan Telaga Pasir berbasis InaSAFE. Hasil analisis menunjukkan debit banjir maksimum PMF dari metode HSS Nakayasu didapatkan sebesar 56,285 m3/dt, maka dilakukan simulasi keruntuhan bendungan menggunakan HEC-RAS 5.0.7 dari beberapa skenario. Luas sebaran genangan banjir terluas akibat keruntuhan Bendungan Telaga Pasir yaitu seluas 14,496 km2 dengan ketinggian banjir maksimum 34,61 m. Berdasarkan hasil sebaran banjir yang dimasukan pada aplikasi InaSAFE maka keruntuhan Bendungan Telaga Pasir dikategorikan bahaya banjir tingkat tinggi. Estimasi kerugian ekonomi yang ditanggung oleh pemerintah dan warga Kabupaten Magetan yang terdampak akibat keruntuhan Bendungan Telaga Pasir penduduk sebesar Rp. 154.225.241.802.
Telaga Pasir Dam is one of Indonesia's natural lakes which provides irrigation water and tourist spot. Despite that, Telaga Pasir Dam is not free from the risk of a dam break along with the age of the dam. The purpose of this study is to determine the maximum flood discharge in the Telaga Pasir Dam catchment area, the flood inundation due to the collapse of Telaga Pasir Dam based on the HEC-RAS 5.0.7 simulation, to classify the hazard level of the collapse, and to estimate the economic losses caused by the collapse of the dam using InaSAFE. The analysis results show that the PMF discharge from Nakayasu method is 56,285 m3/sec. Which then, is used in HEC-RAS for several scenarios. The maximum area affected by the collapse of Telaga Pasir Dam is 14,496 km2 with a maximum flood height of 34.61 m. Based on the results of the flood distribution entered into the InaSAFE program, the collapse of Telaga Pasir Dam is categorized as a high-level flood hazard. The estimated economic loss caused by the collapse of the Telaga Pasir Dam is Rp. 154.225.241.802.