Evaluation of Reservoir Performance on Flood Discharge Plan Using HEC-HMS Modelling (Case Study: Selorejo Reservoir

Abstract

Water is a valuable resource for humanity, because of this fact humanity has to manage the amount of water resource whether it is in excess condition or scarce. excess water is a problem in water management. Because it can cause natural disasters and waste water in vain. Therefore, water needs to be properly regulated. One way to regulate water is by structural means or it can also be called water reservoirs. Reservoir is one of the structures that are suitable to hold water and become a means to regulate the water itself. Referring to the POW (dam operation pattern) and ROTW (annual reservoir operation plan) from the Ministry of PUPR, it is said that the condition of the reservoir must be reviewed for development and changes in its utilization at least every 5 years. The solution chosen to evaluate the selorejo reservoir is to use the Rain-runoff Relationship Model in this case using HEC-HMS version 4.2.1, to find out whether the reservoir is still able to accommodate the flood discharge that was planned at the beginning of construction. Due to the age of the Selorejo Reservoir which has reached 48 years, the Selorejo Reservoir itself is planned with an effective age of 50 years. From analysis result we can conclude that even there is change in reservoir capacity due to sedimentation, Selorejo Reservoir still able to accommodate 1000-year Period Flood and if the reservoir kept in +610 m level, it will be able to accommodate PMF Flood.