<![CDATA[Abstrak Pembangunan kolam retensi Arafuru belum mampu mengurangi frekuensi terjadinya banjir secara optimal karena Jalan Arafuru masih termasuk dalam lokasi titik banjir yang terdapat pada DAS Buah dengan ketinggian banjir antara 50-100 cm dengan durasi 24 jam. Kolam tambahan yang akan dibangun direncanakan seluas 5950 m2 untuk menampung kelebihan kapasitas kolam retensi eksisting. Optimalisasi kapasitas tampung kolam retensi Arafuru dapat dilakukan dengan mengkoneksikan outlet kolam retensi eksisting dengan inlet kolam retensi baru yang memiliki luasan 5950 m2 dengan kedalaman minimal 3 m untuk memenuhi daerah layanan/catchment area dengan luasan ±96,17 Ha. Pendugaan debit puncak limpasan permukaan dilakukan dengan metode SCS-CN dan didapatkan tinggi elevasi muka air maksimum inflow sebesar 11,4 m3/s terjadi pada menit ke 60, sedangkan elevasi puncak yaitu 2,7 m. Simulasi reduksi debit banjir dilakukan dengan software HEC-HMS, didapatkan bahwa penambahan kolam retensi dapat mengurangi debit inflow puncak dari 11,4 m3/s menjadi 7,1 m3/s atau sebesar 37,72%. Kata Kunci: Kolam retensi, analisa hidrologi, analisa spasial, pengendalian banjir Abstract The construction of Arafuru retention basin has not been able to optimally reduce the frequency of flooding since Jalan Arafuru district is still included as one of the flood points within Buah Watershed with flood depths between 50-100 cm and duration of 24 hours. The additional basin is designed to be 5950 m2 in accordance with the area of land that has been acquired to accommodate the over capacity of the existing retention basin. The optimization of Arafuru retention basins capacity can be done by connecting outlet from existing basin to the inlet of the new basin. Retention basin of 5950 m2 with a minimum depth of 3 meters is expected to accommodate runoff from ± 96,17 ha catchment area. The estimation of the peak runoff discharge was carried out using the SCS-CN method and the maximum inflow water level elevation was 11,4 m3 / s occurring in the 60th minute, while the peak elevation was 2,7 m. The simulation of flood discharge reduction using HEC-HMS resulted that the addition of a retention basin could reduce the peak inflow from 11,4 m3 / s to 7,1 m3 / s or as much as 37,72%. Keywords: retention basin, hydrological analyses, spatial analyses, flood control]]>
