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UPSI Digital Repository (UDRep)
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| Abstract : Universiti Pendidikan Sultan Idris |
| The different peak discharge value estimated in the rational method (RM) model is caused by the various methods used to determine the runoff coefficient (C) parameter. The C value can be defined as the total amount of rainfall generated to become the runoff. Various studies have been conducted to produce C values that differ from one to another. For example, the C values suggested by the Manual of Storm Water Management (MSMA) and the American Society of Civil Engineers (ASCE) differed. To estimate C values, land use classification is confusing, unorganized, and not uniform, and therefore, the application of suggested C value is still doubtful to be applied in Malaysia. Thus, this research focused on estimating the C value based on the land use classification for urban areas in Penang using a rainfall simulator. The runoff coefficient will be generated from various surface types at a plot scale representing urban land use. The result obtained shows that the C values were 0.79?0.89 (asphalt), 0.85?0.92 (concrete), 0.77?0.89 (zinc), 0.73?0.85 (brick), 0.85?0.96 (asbestos), 0.8?0.93 (tiled roof), 0.17?0.63 (grass 2�?7�), and 0.35?0.69 (bare soil 2�?7�). The variation of the C value was influenced by the total amount of rainfall, surface imperviousness, soil moisture, soil and surface characteristics, slope, and vegetation cover. There were significant differences in the C value obtained in this study compared to the C value of MSMA (asphalt and brick) and the C value of ASCE (concrete and asbestos, grass, and exposed soil). Four factors that influenced the differences of C values in this research were environmental conditions, namely scale, surface physical condition, and soil antecedent moisture. The multiple comparison test showed a significant difference in the peak discharge estimated using RM compared to the gauged peak discharge. Nevertheless, peak discharge estimated from various C values in the RM did not show any statistical differences. In conclusion, this study found that the rainfall simulator could be used as a suitable and efficient modus operandi in terms of cost and time for runoff studies. ? 2021, Saudi Society for Geosciences. |
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