Evaluation of Krueng Tripa River Capacity in Ujung Krueng Village, Nagan Raya Regency, Indonesia

Abstract

Flood events are very common in the lowlands as often happens in Ujong Krueng Village, Tripa Makmur District. This study aims to determine the magnitude of the design flood discharge using the Nakayasu method and evaluating the cross-sectional capacity of the Krueng Tripa River in Ujong Krueng Village. The data used are both primary and secondary. Primary data consists of measurements of river slope, river flow velocity, river depth and river width, while secondary data consists of rainfall data, Krueng Tripa watershed maps and Krueng Tripa River situation maps. The results of the design flood discharge calculation using the Nakayasu method show that the 2-year return period (RP) is 3237.46 m3/s, the 5-year RP is 4389.53 m3/s, the 10-year RP is 5177.08 m3/s, the 10-year RP is 5177.08 m3/s, the 25-year RP is 6199.32 m3/s, the 50-year RP is 6979.04 m/s, and the 100-years RP is 7778.23 m3/s. From the results of hydraulic analysis on the section of the Krueng Tripa river in Ujong Krueng Village using the HEC-RAS 6.1.0 software, it shows that in the 2-year return period, on pias 1, 7 and 8 experienced overflows on both sides while on pias 2, 3, 4, 5 and 6 only overflow on the right side. In the return periods of 5th, 10th, 25th, 50th - year and 100th, all the streams had overflowed, the highest overflow reached 4.84 m, while the lowest overflow reached 0.30 m.