SIMULASI PERHITUNGAN PROFILMUKA AIR BANJIR DI SUNGAI SANGATA UNTUK MENENTUKAN ELEVASI DASAR JEMBATAN MENGGUNAKAN APLIKASI HEC-RAS --

ABSTRACT
The Sangatta River is located on the island of East Kalimantan and one of
the ship transportation routes, with the bridge project around the Sangatta river
and in addition the Sangatta River experienced a significant increase in water
level, the bridge construction process underwent a design change for the bridge
floor. Therefor water level profile simulation is aimed at providing information
about the flood elevation and the flow rate of the river during the flood. HECRAS software was used for water level profile simulation modeling. The flood
discharge design is calculated with a return period of 1 year 2 years, 5 years, 10
years, 25 years and 50 years using a synthetic unit hydrograph (HSS), the
boundary conditions at the upstream are the discharge design from the HSS and at
the downstream is the normal depth with a slope value of 0.0029. The simulation
results show that around the riverbanks of Sangatta there is an increase in flood
water level of 3.6 m and to determine the elevation of the bridge body (Clearance)
by increasing the MAB height with a minimum clearance of 1 m and the elevation
is 16.6 m
Keywords : Sangatta River, Flood Water Level Modeling, HEC-RAS