The area of flood run-off with HEC-RAS modeling in Cabang Dua River, Manokwari Regency, West Papua Province

Abstract

Abstract Wosi watershed is one of the watersheds with a Classification Restored Carrying capacity, and it is also indicated to have decreased hydrological function. this study aims to find out the extent of the flood discharge plan/peak runoff (m3/s) and plan/peak of the flood affected (ha). This research was conducted in 3 months (September - November 2020). The observed object is Cabang Dua river Wosi, in Manokwari, West Papua. The data of the research results are analyzed descriptively quantitatively with the technique of interpretation and analysis of maps. The results showed the value of flood discharge plan on repeat 2, 5, 10, 25, 50, 100 years respectively are 89.05 m3/s, 118.50 m3/s, 128.46 m3/s, 135.01 m3/s, 137.57 m3/s, and 138.94 m3/s. It is known that Cabang Dua river is unable to accommodate the discharge and causes flooding at any time (2-100 years) with successive areas of 13.88 ha, 14.36 ha, 14.52 ha, 14.60 ha, 14.67 ha, and 14.71 ha.