Assessing seasonal rainfall erosivity variability in East Malaysia: a trend analysis approach

Rainfall erosivity is defined as the parameter that measures the potential impact of rainfall causing soil erosion. Soil erosion is a major global hazard that often results in landslides, infrastructure damage and high mortality rate. It is crucial to consider both the temporal and spatial rainfall distribution because this will assist the professional bodies in improving soil conservation planning to mitigate soil erosion risk. Therefore, this research aims to analyse the temporal and spatial trend of seasonal rainfall erosivity in East Malaysia between 1989 and 2018. The Man-Kendall (MK), Modified Mann-Kendall (MMK) and Sens's slope methods were utilized to compute the temporal trends of rainfall erosivity, whereas Ordinary Kriging (OK) and thiessen polygon were employed to interpolate the spatial trend of rainfall erosivity. The result showed that the majority of rainfall stations exhibited an upward trend during the northeast monsoon, southwest monsoon and first intermonsoon. Contrarily, East Malaysia experienced a downward trend in rainfall erosivity during the second intermonsoon. The spatial trend of rainfall erosivity revealed that the highest rainfall erosivity was concentrated in the southern and central regions of Sarawak during the northeast monsoon. The findings of this paper highlight that East Malaysia is susceptible to landslides, especially during northeast monsoon. Therefore, the implementation of effective erosion control is crucial in reducing landslide hazards.