Analisis Frekuensi Curah Hujan Maksimum di Stasiun Abepura-Waena, Jayapura

Abstrak

Rainfall is a crucial hydrological parameter for the planning of hydraulic structures, drainage systems, and flood control measures. This study aims to determine design rainfall using three frequency analysis methods—Log-Pearson Type III, Gumbel, and Log-Normal—based on annual maximum rainfall data from the Abepura-Waena Station (2001–2010) obtained from BMKG Region V Jayapura. The analysis process involved identifying annual maximum rainfall, calculating statistical parameters for each distribution, determining frequency factors, calculating design rainfall for return periods of 2, 5, 10, 25, 50, and 100 years, and performing goodness-of-fit tests using the Kolmogorov-Smirnov method. The results indicate that all three distributions passed the goodness-of-fit test at a 5% significance level, with calculated $D_{max}$ values ​​of 0.0901 (Gumbel), 0.1022 (Log-Normal), and 0.1024 (Log-Pearson Type III)—all of which were lower than the critical value ($D_{critical}$) of 0.410. Based on the $D_{max}$ values ​​and the lowest average error relative to empirical probability, the Gumbel distribution demonstrated the best fit among the three methods. The design rainfall values ​​derived using the Gumbel method for return periods of 2 to 100 years ranged from 307.9 mm to 849.8 mm. Consequently, the Gumbel distribution is recommended as the basis for planning water resource infrastructure in the Abepura-Waena area, with the Log-Normal and Log-Pearson Type III distributions serving as viable alternative methods for comparison.