STUDY OF TIDAL INFLUENCE ON FLOODING IN KECAMATAN SELAKAU

Kecamatan Selakau has a considerable risk of flooding, which occurs every year. Because it low topography, its location on the coast is undoubtedly greatly influenced by tides and prone to tidal flooding. In an effort anticipate reduce duration frequency rain arranging drainage system through technical study activities channels, especially Nyirih River channel, empties directly into River.This research aims examine effect River's flow combination rainfall incidence flooding in channel. The methodology used descriptive method. Hydrological analysis using maximum daily data from Tebas Station. Then water level readings design discharge are hydrodynamic model analysis.Based results HEC-RAS Version 6.1.0 software, elevation sta at highest tide conditions without rain. 0+000 sta. 1 + 466,682 exceeded existing channel cross-section so that experiences inundation with height 0.02 m–0.4 m, 694,439 2 073.878, still below cross-sectional no occurs. It shows there or increase for return periods 2, 5, 10, 20 years, same as rain, experience m-0.4 m. Normalization inefficient unsuccessful decreasing floods since sea extensively impact along river