Hydraulic Effect Analysis Of Channel Short-Cut In Meandering River

Abstract

Short-cut is one offlood control technique in meandering river especially in downstream reach. In some cases, this technique is still used although in eco-hydraulic concept, it is less effective and on the contrary, it causes bigger flood on downstream river. This research is to know the effect of short-cut on flood characteristic by using DonginRiver in Banggai Regency as model.This research is conducted with hydrology analysis to the rainfall and watershed data to set flood hydrograph as upstream boundary condition. The simulation deals with flood routing by using HEC-RAS hydrodynamic models to know the hydrograph, water surface, velocity and energy line along the river reach. To obtain the optimal parameter value, formerly, HEC-RAS must be calibrated by adjusting simulated water surface with observed water surface in a cross section.The result of simulation using annual discharge (Q =123.54 m3/s) showed that the short-cut affect the flood characteristic and water surface profile. In downstream, the short-cut cause the peak time of hydrograph (tp) shorter (1 hour) and increase the velocity (insignificant) and water surface (5.4 %). In upstream, the short-cut decrease water surface (10.14 %), increase the velocity (31.80 %) and energy line.Therefore, short cut is recommended to control the flood.