Flood Control Rule in Bintang Bano Reservoir

Abstract Flood is a disaster that occur since ancient times until now, and even in the future. Flood can be caused by nature, humans, or both. Constructing new dams are a good method to reduce flood and losses caused by floods, one of them is Bintang Bano Dam. The purpose of this study is to analyze the capacity of the gated spillway and ungated spillway, so that the allowable return period of discharge can be estimated through the both spillways. This research activity divided into 4 (four) stages are: the identification and data processing stage, the rainfall-runoff modeling stage, the reservoir flood routing, and the simulation of the operation of opening gates on both spillways. The gated spillway can be operated at all return periods (2 years to PMF). Ungated spillway can only overflow discharge with ≥ 100 years return period. During the return period 2 years to 50 years, no runoff occurs through the ungated spillway. For the return period of 100 years to 1000 years there is runoff through the ungated spillway without any gate openings. It is recommended for floods with a return period of 2 years to 50 years, with upstream and downstream conditions of rainfall, the gate can be closed. But for floods with 100 years to 1000 years return periods, the discharge automatically overflows through the ungated spillway cannot be opened/damaged.