Analisis Hidrologi dan Debit Banjir Rancangan pada Sistem Drainase Jalan Pulau Roti Desa Pedungan Denpasar

Abstract

Denpasar has undergone rapid development, leading to reduced water absorption capacity and increased surface runoff. The Jalan Pulau Roti area in Pedungan Village frequently experiences flooding, with inundation depths ranging from 10 to 30 cm. This study aims to analyze hydrological characteristics, test rainfall data consistency, and determine design rainfall and design flood discharge. A quantitative hydrological research method was employed using maximum daily rainfall data (2011–2025) from the Sanglah, Suwung, and Sumerta stations. Data consistency was verified using the Double Mass Analysis (DMA) and Rescaled Adjusted Partial Sums (RAPS) methods. Design rainfall was calculated using the Log Pearson Type III distribution, with goodness-of-fit verified via the Smirnov-Kolmogorov and Chi-Square tests. Design flood discharge was calculated using the Rational Method. RAPS test results indicated data consistency (Q/√n = 0.235 < 1.10 and R/√n = 0.044 < 1.34). Log Pearson Type III calculations yielded design rainfall values (R₂₄) of 351.400 mm (5-year return period), 536.186 mm (10-year), and 875.007 mm (25-year). Rainfall intensities were calculated as I₅ = 53.580 mm/h, I₁₀ = 81.756 mm/h, and I₂₅ = 133.419 mm/h. The resulting design flood discharges were Q₅ = 1.192 m³/s, Q₁₀ = 2.007 m³/s, and Q₂₅ = 3.559 m³/s. These results serve as the primary quantitative basis for the redesign of the drainage system.