Normalization of Suak Ujong Kalak estuary as a flood reduction effort for Meulaboh city

Abstract Meulaboh City frequently experiences flooding, with runoff flowing into the Suak Ujong Kalak Estuary, a natural outlet for the city’s drainage system. Currently, the estuary is unable to effectively accommodate the runoff, exacerbating the flood risk. This study aims to evaluate the existing condition of the Suak Ujong Kalak Estuary and propose a normalization plan to improve flood control. The research employs a descriptive-quantitative methodology, involving field surveys, data collection, and hydrological and hydraulic analyses. The hydrological analysis includes rainfall frequency analysis, chi-square testing, and rainfall intensity calculation using the Mononobe method. Flood discharge estimation is based on the Rational method for a 25-year return period. Hydraulic analysis is conducted using HEC-RAS 6.3.1 software. The results show that the estuary receives an inflow of 79.33 m 3 /second, which exceeds its current capacity. Hydraulic analysis reveals that the estuary cannot accommodate the discharge, causing overflow with an average height of 0.6 meters and a storage capacity of 40,798.43 m 3 . To address this, the study recommends a normalization effort, involving excavation with an average depth of 1 meter, to improve the estuary’s capacity and reduce flooding in Meulaboh City.