Pattern of flooding in Kelantan due to extreme rainfall and tidal phenomenon

Abstract

Malaysia is one of the countries that experiences the flood phenomenon. Every year, the east coast of Malaysia experiences the northeast monsoon season which brings episodes of extreme rainfall and causes floods. The season starts in November until early March. Flooding that occurred in Kelantan in 2014 was the biggest flood that hit Malaysia and this led to huge losses and endangered people‟s life. Thus, a flood simulation system needs to be conducted as an early precaution to address the flood phenomena. This research analysed a simulation of flood pattern over a period of seven years using ArcGIS software to obtain the area and volume of potential flooding. The area involved in this research is adjacent to a tidal station located in Geting, Kelantan. Besides, other areas included in the research were Keretapi Tumpat station, Department of Irrigation and Drainage (DID) Kota Bharu Store, Chabang Tiga Pendek and Pump House Salor. These area were considered by identifying the pattern of rainfall distribution within these areas using interpolating method. Besides, the water level and streamflow station at Guillemard Bridge of Kelantan river and Lebir river were included in this research to develop the relationship between water level, streamflow and tidal activity with flood occurrence. The methodology comprised three main specific parts which is the generation of flood depth, floodplain areas and simulation of floodplain region, relationship between water level and streamflow and simulation of tidal phenomena in Kelantan. Data used in the research is Digital Elevation Model (DEM) and boundaries of Kelantan state. These data were digitized to combine all the data including cross-section data of Kelantan river to generate the floodplain areas and simulation of flood phenomenon. This research focused on the effect of tidal phenomena and extreme rainfall towards flood occurrence. Other than that, astronomical factors were studied where the distance of the moon to the earth affects tidal activities. The positions of the moon near to the earth caused high tides at that time. During the flooding in year 2014, Malaysia experienced a new moon phenomena and this caused high tides and contributed to the major flood occurrence. Interpolation method resulted in patterns of rainfall distribution that were different every year but the highest rainfall distribution frequently happened at the area of Pump House Salor. Plotted graph showed that water level and streamflow had a linear relationship which had the highest value of data that occured in 2014. This was shown through the simulation of flooding for the year 2014 and the results showed that the biggest potential areas of flooding were at Guillemard Bridge of Kelantan river and Lebir river with a total area of 126,459,291 m² and total volume of 1,369,390,421 m³. The findings have shown that the use of flood simulation can be used to monitor flood activities where the potential areas of flooding can be identified based on the data related to extreme rainfall, water level, streamflow and tidal activities in the future. Based on these flood simulations, the value of the water level that can cause flooding in a specific area can be identified and can be serve as an early precaution for the community and authorities to prepare for the flood as this can reduce the loss of property and save many lives.