Statistical Analysis of 30 Year Rainfall Data: A Case Study for Langat River Basin

Abstract

Rainfall is an important factor in civil engineering as it affects the design of hydraulic structures, bridges and culverts, canals, storm water sewers, road drainage systems, etc. This paper presents the statistical analysis of 30-year rainfall data collected at eight rainfall stations within the Langat River Basin. Ten plotting position methods were utilised to evaluate the return period of annual rainfall. The yearly rainfall was computed to assess the variability of rainfall based on the determined results; the pattern of rainfall is irregular. Weibull Distribution from Plotting Position methods is found to best fit the annual rainfall data. The findings provide the insights for determining the correct commencement and cessation of monsoon results, which have the effect on land utilisation, flood forecasting and emergency planning. This analysis contributes to water management, water resource planners, farmers, and urban engineers to evaluate the availability of water and develop the storage accordingly.

Keywords

• Weibull distribution
• Rainfall
• Precipitation
• Langat river basin
• Plotting position.