Navigating Environmental Risks Exploring the Effects of Flood Hydrographs and Probable Maximum Floods in a Series Cascade Reservoir System A Case Study

The Saguling, Cirata, and Jatiluhur reservoirs in Indonesia form a crucial Series Cascade Reservoir System (SCRS) that provides numerous benefits, including energy production, irrigation support, and a reliable clean water supply to diverse regions. However, the presence of these reservoirs also poses the risk of flooding, underscoring the necessity of maintaining their long-term functionality while considering environmental perspectives. In this study, an analysis of daily inflow data from 2000-2015 was conducted to investigate the water loss aspect of each reservoir, compare distribution characteristics, and assess the potential for unit hydrological analysis and probable maximum flood (PMF). Utilizing four distribution approaches, the study aimed to determine the maximum flood discharge with return periods ranging from 25 to 1000 years. Results revealed that the maximum peak discharge was measured at 37.4 m3 /s for the Saguling reservoir, 52 m3 /s for the Cirata reservoir, and 43.4 m3 /s for the Jatiluhur reservoir. Additionally, the PMF analysis identified sequential delays of 4 hours for each reservoir, with confirmed PMFs occurring at the 10th, 14th, and 18th hour for Saguling, Cirata, and Jatiluhur reservoirs, respectively. The corresponding maximum capacities for these events were determined as 18510.5 m3 /s, 44316.2 m3 /s, and 66418.2 m3 /s.