Flood analyses at downstream of Cimadur River in Upper Cimadur Basin using HEC-RAS

Abstract

Cimadur Basin has faced recurring flood issues in recent years, particularly downstream of the Cimadur River during the rainy season. This condition has drawn the attention of local engineers and water resource managers. This study aims to address these flood problems by identifying the most critical floodprone areas along the Cimadur River. To achieve this, we simulated floodwater levels for various return periods (5, 10, 25, 50, and 100 years) using HEC-RAS software. Field measurements were conducted to obtain cross-sectional data for the Cimadur River, and land-use information for the Cimadur Basin was sourced from PT Saeba. The analysis using HEC-RAS revealed that seven downstream locations along the Cimadur River experience extreme floodwater levels during heavy rainfall, making them highly susceptible to severe flood impacts. In these locations, three are in proximity to residential areas, two are adjacent to rice fields, and the remaining two are close to crop areas. The flood events in these seven areas pose a significant risk to local residents’ safety, endanger surrounding structures, and threaten crop yields in rice and crop fields. Addressing these flood-prone zones is crucial for safeguarding the well-being of the community and minimizing damage.