DAM BREAK MODELLING BY USING HEC-RAS AND HEC-GEO RAS: A CASE STUDY OF DIRE EMBANKMENT DAM ON LEGADADI RIVER

Abstract

Dam is essential hydraulic structure constructed across river for the purpose of creating reservoir to store water. The study focused on piping dam breach analysis of Dire dam located in Oromiya region. The analysis was carried out through HEC-RAS and HEC-Geo RAS model integrates with GIS. Unsteady flow simulation was done in HEC-RAS model. HEC-Geo RAS model prepares geometric data of Legadadi River in GIS. Input data for HEC-RAS model, dam breach parameters were calculated by using the empirical method of Froehlich 2008. The breach parameters value of breach bottom width (B), breach formation time (tf), and breach side slopes (bss) for piping failure mode were 45.98 m, 0.75 hr, and 0.7. The maximum breach outflow discharge 7712.10 m3 /sat the dam location due to piping failure was found through unsteady flow simulation performed in HEC-RAS model.