http://redac.eng.usm.my/html/projects/flood%20risk%20map/Sg.%20Pahang.htmlProject Title: Digital Flood Mapping: Case Study Of 2007 Sungai Pahang FloodFunder: Research University GrantDuration: 15th August 2009 - 14thAugust 2011

Researchers: Prof. Aminuddin Ab Ghani Prof. Nor Azazi Zakaria Zorkeflee Abu Hasan Leow Cheng Siang Chang Chun Kiat

Executive Summary:Several major floods have been experienced in Malaysia for the last few decades. Flood occurrences seem to be getting more frequent in recent years, especially in some cities like Kuala Lumpur, Penang and Kuching where rapid urbanisation is taking place. After several dramatic flooding events struck the country with dramatic lives and property losses since the 1960s, the government has taken several positive steps and seriously planning to envisage flood mitigation projects in its national plans, translated substantially by the establishment of the Natural Disaster Relief Committee in 1972 and the Permanent Flood Control Commission in December 21, 1971 purposed for to study short-term measures to prevent the occurrence of floods and long-term measures for flood mitigation. In this study, results are presented to develop a digitally flood map for the 2007 flood inundation areas along Sungai Pahang by gathering hydraulic and hydrologic data. This will allow a proper evaluation on the impact of future flood events and advise the implementing agencies as to what steps need to be undertaken to provide further preventative measures to avoid the anticipated flood problems that might occur.Research Background:Malaysia is fortunate in that historically it has not experienced natural disasters in the form of earthquakes, volcanoes, and typhoons. The most common natural disaster frequently encountered in Malaysia is flooding. Two major types of floods occur in Malaysia, including monsoon floods and flash floods. The Department of Irrigation and Drainage (DID) in Malaysia has estimated that about 29,000 sq. km, or 9%, of the total land area and more than 4.82 million people (i.e. 22% of the population) are affected by flooding annually. The damage caused by flooding is estimated to be about RM915 million (Chan, 2005). Whilst monsoon floods are governed by heavy and long durations of rainfall, more localized flooding, which occurs especially in newly developed town areas, has been reported more frequently in recent years. In October 2003 major flooding affected a large area in the northwestern part of the Peninsular, including the states of Kedah, Penang and Northern Perak. The December 2007 flood (Figure 1), on the other hand, occurred in the state of Pahang, after more than 30 years (DID, 1974) since the last similar floods of 1971 (Figure 2, Tables 1 and 2). Flash floods have occurred more frequently in the country since the 1980s, with these types of floods often having a drastic impact on parts of the country. Two common approaches adopted in reducing the impact of flood problems have been increasingly adopted in Malaysia and these include structural and non structural measures. Structural measures include such measures as river widening, deepening and straightening, with the aim being to reduce the magnitude of the flood, but at the same time this approach often transfers the flooding problem further downstream. For non structural measures, tools such as computer models can be used to quantify the effects of human interference to the river system. Such tools are already available widely used in many countries worldwide, but the application of sophisticated models is still relatively new in Malaysia (Chang et. al 2008, Leow et al. 2009). One reason for this limited use of such models in Malaysia is that the tools often do not properly model the more extreme flood events, where the river flows are often supercritical. In Malaysia it is regarded as increasingly important to carry out a thorough analysis of flood events with the help of available river models to understand the flood behaviour before any structural measures are undertaken. Therefore, before any amendments are implemented within a catchment and the flood plain, river engineers must evaluate the potential extent and impact of flood events and advise the implementing agencies as to what steps need to be undertaken to provide further preventative measures to avoid the anticipated flood problems that might occur (Ab. Ghani et al. 2009).The present research will provide the required data on flood inundation of 2007 Sungai Pahang flood for future computer modelling purposes.

Figure 1: December 2007 flood at Pekan, Pahang

Figure 2: January 1971 flood profile (DID, 1974)Table 1: Water Surface Slope in January 1971 flood (DID, 1974)Table 2: Flood Slope in January 1971 flood (DID, 1974)Objectives of the Research: a) To gather hydraulic and hydrologic data of the 2007 flood b) To digitally map the 2007 flood inundation areas along Sungai Pahang c) To estimate damage cost due to 2007 flood Study Area:Sungai Pahang is the longest river in the Peninsular Malaysia at 435 km, the river drains about three quarters of the land area in the state of Pahang (Figure 3). Sungai Pahang actually begins from Kuala Tembeling at the confluence of two equally large and long rivers, the Jelai which drains from the eastern slopes of the Banjaran Titiwangsa, the main range of Peninsular Malaysia, and the Tembeling which has its headwaters in the Terengganu Highlands in the east. Other main tributaries of Sungai Pahang are the Semantan, Teriang, Bera and lepar.Four major towns are located on or near Sungai Pahang and its tributaries: Pekan, the royal town at its mouth; Temerloh midway on the river at its confluence with Semantan; Jerantut, the gateway to Taman Negara on the Tembeling; and Kuala Lipis at the mouth of the river bearing the same name on the Jelai.

Figure 3a: Pahang River Basin (DID, 1974)

Figure 3b: Satellite Image coverage on the Study Area

Figure 4: On-Site Ground Survey and Validation using Professional Data Mapper for GPS Data Collection and Mapping

Figure 5: DEM Development

Figure 6: Comparison of Flood Inundation Area of Model with Actual Condition

Figure 7: Proposed Flood Mitigation Alternatives for Sungai PahangSelected Publications: Ab. Ghani, A., Chang, C.K., Leow, C.S., & Zakaria, N.A. (2012). Sungai Pahang Digital Flood Mapping: 2007 Flood, International Journal of River Basin Management, pp. 1-10, DOI: 10.1080/15715124.2012.680022. Azamathulla, H.Md., Ab. Ghani, A., Leow, C.S., Chang, C.K. & Zakaria, N.A. (2011). Gene-Expression Programming for the Development of a Stage-Discharge Curve of the Pahang River, Journal of Water Resource Management,DOI: 10.1007/s11269-011-9845-7. References: Ab. Ghani, A., Zakaria, N.A. & Falconer, R.A. (2009). Editorial, River Modelling and Flood Mitigation: Malaysian Perspectives, Water Management Journal, Vol. 162, No.1, pp. 1-2, ISSN 1741-7589. Chan, N.W. (2005). Sustainable Management of Rivers in Malaysia: Involving All Stakeholders, International Journal of River Basin Management, Vol. 3, No. 3, pp. 147-162, ISSN: 1571-5124. Chang, C.K., Ab. Ghani, A., Abdullah, R. & Zakaria, N.A.(2008). Sediment Transport Modeling for Kulim River: A Case Study. Journal of Hydro-Environment Research, IAHR, Vol. 2, No.1, pp. 47-59, ISSN: 1570-6443. Department of Irrigation and Drainage or DID (1974). Pahang River Basin Study, Vol. 3: Basin Hydrology and River Behaviour. Leow, C.S., Abdullah, R., Zakaria, N.A., Ab. Ghani, A. & Chang, C.K. (2009). Modelling Urban River Catchment: A Case Study in Malaysia. Water Management Journal, Institution of Civil Engineers (ICE), UK, Vol. 162, No.1, pp. 25-34. ISSN 1741-7589.