Kelantan Big Yellow Flood 2014: Statistical Analysis on Relationship between Rainfall Intensity and Water Level

Abstract

This paper interpreted statistically the relationship between event of weather activities and flooding in the affected area of Kelantan State in Malaysia during the Big Yellow flood event in December 2014. This is an extreme flood event in Kelantan since 1927 with the return period approximately 1 in 1000 years. The rainfall intensity and river discharge dataset from Department of Irrigation and Drainage (DID) Malaysia in four selected study areas were descriptively analysed and interpreted using hyetograph and hydrograph. Furthermore, this descriptive results have been validated inferentially using Chi-Square statistical test that are applied into the primary data gathered from observation and distribution of a questionnaire to flood victim during a field visit at the same selected study area used in analyzing secondary data from DID. The results from descriptive analysis using hyetograph and hydrograph showed two phases of extreme rainfall in the Kelantan river basin. The first phase from 15 to 19 December 2020 pointed out that the heavy rainfalls contribute to the increase of water levels in Galas, Lebir, and Kelantan rivers. Areas of affected flooded are Kota Bharu, Tualang, Kursial, and Kuala Krai from 17 to 19 December 2014. The second phase from 20 to 24 December shows higher intensities of rainfall, especially at the upstream of the River basin in Gunung Gagau and the flooded situation become more severe due to the full capacity of soils, river, and drainage. This study also shows that the flood depth that occurred in the flood-prone area has a significant association with rainfall intensity but not with the distance of the area from the river. The findings can significantly conclude that the Kelantan big yellow flood 2014 is totally influenced by heavy rainfall.