Flood study in Kangar

Abstract

Floods are becoming common in Perlis. A series of floods in November 2010 flooded the state and neighboring Kedah starting from 2005, followed by 2010 and 2011. An unusual rainfall distribution, which causes water levels at rivers to increase and discharging water from Timah Tasoh Dam were two main factors leading to flood. This study has been conducted to study the effect of annual rainfall that contributed to flood in Perlis as well as to study the operation of Timah Tasoh Dam that leading to the flood occurred in Kangar, Perlis on 2005 and 2010. All the data that are related to the flood was collected using different surveying and from various sources such as existing maps, reports and also documentation before being analyze to have some overview regarding flood problem in Kangar. Data such as rainfall data, Timah Tasoh operation, river and drainage were required in this study. For Hospital Kangar Rainfall Station the highest recorded rainfall was on December 2005 which is 472.8 mm. Then, for year 2010, the highest data recorded was on November, which is 422.6 mm. In 2005 and 2010, large floods have occurred in Perlis caused by unusually heavy rain that continued for three days in a row throughout Perlis. The normal level of the dam is set to 29.10 m. The alert level is set to 29.40 m. The warning and danger level are set to 29.5 m and 29.6 m respectively. In 2010, Perlis was hit by unusual heavy rains continued for three days starting on 30th October to 1st November 2010. This condition causes water retention of Timah Tasoh Dam achieved maximum level of 30.49 m, 29.60 m above the danger level. On October 31, 2010, the Department of irrigation and Drainage has open four spillway gates with 0.2 m of water discharge rate when the water level dam reached 29.12 m. On 2 November 2010, to avoid larger disaster, the Department decided to open all six spillway gates at the rate of expression of 0.7 m although the dam reached 30.49 m. Release of dam water with a total volume of water has resulted in large-scale river water spills out and there is flooding in the area. Heavy rain throughout the state have caused water in all major rivers were flowing out of the State of Perlis and flooded areas surroundings.