Assessment on rainfall erosivity with regard to the flood occurrence at major river of Peninsular Malaysia
2004
Roslan Zainal Abidin | Janmaizatulriah Jani
In Malaysia, major flood events usually occur during the North-East Monsoon due to continuous heavy rainfall. As much as 9% of the land areas in Malaysia, amounting to 29,000 sq. km is flood prone. Large floods had damaged properties, public utilities, cultivation, and loss of lives and also caused hindrance to social and economic activities. Average annual flood damage amounts to RM 100 millions as quoted by the Department of Irrigation and Drainage, Malaysia. In this context, rainfalls as the main agent in causing flood. Thus, the focus of this research is on analysing aspects of rainfall and particularly its erosivity with regards to flood occurrence. In order to get the idea of the erosive properties of rainfall, the intensity, duration, total rainfall and kinetic energy of the rainfall have to be considered. These properties are based of recorded flood event occurrence. By knowing all this properties, a relationship between amount of rainfall erosivity and the types of flood occurrence can be linked. The method adopted in analysing the rainfall erosivity is the R factor of the universal Soil Loss Equation. Up to date, there is no research of this kind in creating a number with respect to the type of flood. As a result of this research finding, "ROSJAN`s Numbers" has been created to relate the type of flood occurrence mainly minor, moderate and major/flash flood. It is hope that the outcome of this research can be used in forecasting the possible flood prone areas in Malaysia which depend on rainfall erosivity factor.
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