Electronic Theses and Dissertation

Bencana alam banjir dapat terjadi karena limpasan air sungai yang keluar dari alur sungai saat kapasitas sungai tidak mampu menampung aliran yang terjadi. Banjir akibat luapan air sungai juga terjadi di salah satu Daerah Aliran Sungai (DAS) yang ada di Aceh yaitu DAS Tripa. Banjir yang terus berulang tentu menjadi keresahan bagi masyarakat yang tinggal di sekitar daerah Sungai Krueng Tripa. Maka dari itu diperlukan kajian awal untuk melihat sebaran genangan banjir akibat dari meluapnya Sungai Krueng Tripa. Dalam menetapkan sebaran genangan banjir diperlukan analisis banjir rencana dengan metode Hidrograf Satuan Sintetis Soil Conservation Service (SCS) untuk mengetahui besaran debit banjir yang terjadi di Krueng Tripa dengan periode ulang 2, 5, 10, 25, 50 dan 100 tahun. Nilai debit banjir maksimum yang didapatkan untuk tiap periode ulang ialah sebesar 1273,35 m³/dt, 2092,41 m³/dt, 2670,03 m³/dt, 3361,64 m³/dt, 4036,57 m³/dt, dan 4664,72 m³/dt. Hasil perhitungan debit banjir di-input kedalam software Hydrologic Engineering Centers River Analysis System (HEC-RAS) 2D dengan aliran unsteady flow untuk melihat sebaran genangan banjir. Pembentukan peta genangan banjir dibantu dengan software ArcGIS 10.8.2. Pemodelan genangan banjir menggunakan software HEC-RAS menghasilkan luasan sebaran genangan banjir pada periode ulang 2, 5, 10, 25, 50, dan 100 tahun sebesar 41,29 km², 68,14 km², 86,66 km², 108,35 km², 128,58 km², dan 142,54 km². Validasi genangan banjir hasil pemodelan HEC-RAS dengan titik sebaran banjir didapatkan persentase genangan banjir dengan periode ulang 2, 5, 10, 25, 50, dan 100 tahun masing-masing menggenangi 3,45%, 27,59%, 46,55%, 77,59%, 82,76%, dan 91,38% titik sebaran banjir di DAS Tripa.

Flood natural disasters can occur due to river water runoff coming out of the river channel when the river capacity is unable to accommodate the flow. Flooding due to overflowing river water also occurred in one of the watersheds in Aceh, namely the Tripa Watershed. Recurring floods are certainly a concern for the people living around the Krueng Tripa River area. Therefore, a preliminary study is needed to see the distribution of flood inundation resulting from the overflowing of the Krueng Tripa River. In determining the distribution of flood inundation, a planned flood analysis using the Soil Conservation Service (SCS) Synthetic Unit Hydrograph method is required to determine the magnitude of flood discharge in Krueng Tripa with return periods of 2, 5, 10, 25, 50, and 100 years. The maximum flood discharge values obtained for each return period were 1273,35 m³/s, 2092,41 m³/s, 2670,03 m³/s, 3361,64 m³/s, 4036,57 m³/s, and 4664,72 m³/s. The results of flood discharge calculations were input into the Hydrologic Engineering Centers River Analysis System (HEC-RAS) 2D software with unsteady flow to see the distribution of flood inundation. The formation of flood inundation maps is assisted by ArcGIS 10.8.2 software. Flood inundation modeling using HEC-RAS software produced flood inundation distribution areas for return periods of 2, 5, 10, 25, 50, and 100 years were 41,29 km², 68,14 km², 86,66 km², 108,35 km², 128,58 km², and 142,54 km². Validation of flood inundation results from HEC-RAS modeling with flood distribution points showed that the percentage of flood inundation with return periods of 2, 5, 10, 25, 50, and 100 years respectively inundated 3,45%, 27,59%, 46,55%, 77,59%, 82,76%, and 91,38% of flood distribution points in the Tripa Watershed.