Contribution of Manggarai gate improvement to flood in Manggarai Village based on recorded flood event

Manggarai Gate is one of the most important flood control structures of the Jakarta Flood Control System. Its performance capacity is a compulsory parameter for flood risk reduction of the Jakarta Flood Prone Area. This paper aims to evaluate the contribution of the capacity improvement of Manggarai Gate to reduce the flood hazard at Manggarai flood-prone areas located in the upper part of this gate. An additional gate section was conducted in 2015 as the structural flood hazard reduction effort to increase the capacity of this gate from 330 m3/s to 507 m3/s. Recorded floods characteristic event before and after this improvement was compared to determine the flood hazard changes during the flood observation period. Based on this determination results it is found that the contribution of the increment capacity of Manggarai gates in reducing the flood hazard depends on the sustainability of the river capacity, river water quality, and flood control operation. It could also be concluded the sustainability of the river capacity and river water quality is very sensitive to the social behavior of the community and the river stakeholder along the river catchment area in addressing the environmental condition of the river catchment area.