Study flood routing Mamak Dam and evaluate the River Mamak to convey the flood design, Lombok, Indonesia

Abstract

The purpose of this study was to determine the effectiveness of the Mamak Dam in controlling the volume of flooding and the capacity of the Mamak River to deliver the design flood. The investigation was carried out with a survey at the study site and collected secondary data. The methodology carried out was in the form of routing floods through reservoir by routing floods through the level pool routing. The profile of the Mamak River uses unsteady flow with the of HECRAS 4.1 software. The conclusions from this study are: 1). Mamak Dam can extend the peak flood time from 5 to 6 hours to 10 to 12 hours; reducing the flood of Mamak Dam between 107.51 m3/s to 232.96 m3/s or equivalent to 60.44% to 41.75% according to the return period of the flood discharge. 2). The flood discharge that comes from the overflow of the Mamak Dam is not able to be fully flowed by the Mamak River resulting in flooding, both annual flooding and for 25 years return period. 3). To overcome this flood, the flood dikes planned to vary in height from 0.81 m to 3.2 m.