Study of Drought Using the Theory of Run and Hydrological Drought Index and its Relationship to Reservoir Storage at the Batujai Dam and Pengga Dam

Abstract

Drought is a frequent disaster in Indonesia, particularly in areas with long dry seasons. Several factors influencing drought in Indonesia include irregular rainfall patterns, climate change, and unsustainable water resource usage. This study was conducted to provide an overview of drought and its impact on the storage of the Batujai Dam and Pengga Dam. This research utilizes drought analysis and reservoir simulation analysis. The results of this study are as follows: a) The drought condition at the Batujai Dam based on the Theory of Run method has a maximum deficit value of -644.66 mm, and the drought based on the Hydrological Drought Index using inflow data from 2013 to 2022 has a maximum deficit value of -2.88 m³/s. Meanwhile, the drought condition at the Pengga Dam based on the Theory of Run method has a maximum deficit value of -407.86 mm, and the drought based on the Hydrological Drought Index using inflow data has a maximum deficit value of -2.371 m³/s. b) The impact of drought on the simulation of the Batujai Dam and Pengga Dam over specific periods shows that the Batujai Dam was full (overflowing) for 7 dekadal periods, whereas under existing conditions, it was never full. The Pengga Dam was full (overflowing) for 6 dekadal periods, while under existing conditions, it was only full once, with a K Factor (ratio of water supply to water demand) having a minimum value of 20% from October I to October III, 2018.