Modeling the Distribution of Rainfall Intensity using Hourly Data

Abstract

Problem statement: Design of storm water best management practices to control runoff and water pollution can be achieved if a prior knowledge of the distribution of rainfall characteristics is known. Rainfall intensity, particularly in tropical climate, plays a major role in the design of runoff conveyance and erosion control systems. This study is aimed to explore the statistical distribution of rainfall intensity for Peninsular Malaysia using hourly rainfall data. Approach: Hourly rainfall data were collected from twelve stations spread across the Peninsular. Six hour separation time was used to divide the data into individual rainfall events and four probability distributions namely, Generalized Pareto (GP), Exponential (EXP), Beta (BT) and Gamma (GM) distributions were used to model the distribution of the hourly rainfall intensity. Kolmogorov-Sminov anderson-Darling and Chi-squared goodness-of-fit tests were used to evaluate the best fit. Results: The rainfall frequency, based on 6 h minimum inter-event time, ranges from 115-198 events. The distribution of the rainfall frequency and that of the highest intensity observed, over the recorded period, across the peninsular, is however irregular. The mean rainfall intensity ranges from 2.32-3.88 mm h −1. Kuala-Lumpur and Penang received the highest, while Segamat and Kedah received the lowest. Conversely, over the period of record, Segamat recorded the highest CV, skewness and kurtosis while Pahang has the least value for these parameters. Goodness-of-fit tests at 5% level of significance indicate that all the models can be used to model the distribution of rainfall intensity in Peninsular Malaysia. However, GP is found to be the most suitable model among the four probability distributions tested. Conclusion: Basic statistics of hourly rain intensity were obtained and probability distributions compared. It was found that GP is the most suitable model. Results can be useful, particularly, to agricultural and storm water management planning.

Frequency Analysis of Annual Maximum Flood for Segamat River

“…These result is differ from the finding by Mohd Daud et al [14], which stated that GEV is the most suitable distribution for annual maximum rainfall in Peninsular Malaysia. However, it is in agreement with those obtained by Dan'azumi et al [16] where in their study, GP is found to be the most suitable distribution for modelling the hourly rainfall intensity in Peninsular Malaysia. Furthermore, this findings are in accord with another study by Wan Zin et al [17], indicating that GP is the most frequently selected fitting distribution of annual maximum rainfall in Peninsular Malaysia based on LQ-moment methods, together with Generalized Logistic distribution.…”

Level of Water Awareness at Some Jordanian Universities Student’s

“…Many Studies discussed some aspects of Water awareness such as- (Damanhouri, 2010;Dan'azumi et al, 2010) that study discuses the effect of raising the environmental awareness on reducing kitchen water, the result showed that the average consumption of kitchen water was 59/L/day/family, reduced after raising environmental awareness to 49.5 L/day/family, with an average of 9.5 L/day/ /family, which is very vital indicator. Anderson (2010) discussed unclean drinking water and concluded that the household don't have alternatives for water treatment; only 19%of them treated drinking water used the following means:-boiling 51.3%,chemical treatment 42.3%, filtering 6.1%, others3%.The study also showed that boiling unclean drinking water needs more amount of water, increased more consumption of foul, requires additional household labor and chemical treatment was more desirable, it's coasted more money in situation where households were very poor.…”

Fitting the distributions of wet spell duration with probability models

“…Four candidate distributions, namely, Exponential, Gamma, Weibull and Mixed exponential were tested from twelve stations in Wilayah Persekutuan, Malaysia, and it was concluded that the Mixed exponential distribution fits better for hourly rainfall in the area [9]. Hourly rainfall data was used to study the statistical distribution of rainfall depth and rainfall intensity for Peninsular Malaysia and four candidate distributions namely, Generalized pareto, Exponential, Beta and Gamma were tested and the result indicated that models can be used to fit rainfall depth and intensity for Peninsular Malaysia [10].…”