ANALISIS DISTRIBUSI CURAH HUJAN KAWASAN TANJUNG SENAI KABUPATEN OGAN ILIR

Rainfall is one of the important factors in water resource planning and management, both for social and economic aspects. The Tanjung Senai area in Ogan Ilir Regency, which is drained by the Kelekar sub-watershed, is highly dependent on water availability, especially for agriculture and settlements. This study aims to analyze rainfall distribution and determine design rainfall intensity with various return periods (5, 10, 20, 50, and 100 years). The research method uses a quantitative approach with analysis of secondary rainfall data from the BMKG for 10 years (2014–2023). The analysis stages included frequency analysis, probability distribution analysis (Normal, Log Normal, Log Pearson Type III, and Gumbel), distribution suitability tests (Chi-Square and Kolmogorov-Smirnov), rainfall intensity calculations using the Mononobe method, and the preparation of a design rainfall hyetograph using the Alternating Block Method (ABM). The results show that the analysis of rainfall distribution in the Kelekar Sub-DAS indicates that the Gumbel distribution method is the most appropriate for representing extreme rainfall in the region. The rainfall intensity analysis shows that the R24 rainfall value for a 5-year return period is 169.956 mm/hour, a 10-year return period is 187.392 mm/hour, a 20-year return period is 204.118 mm/hour, a 50-year return period is 225.767 mm/hour, and for a 100-year return period is 241.989 mm/hour. Thus, the results of this study are expected to make a significant contribution to the development of sustainable environmental policies and management in the Tanjung Senai area.Keywords: Rainfall data. Rainfall intensity, Frequency distributionA. Pendahuluan