Journal of Coastal Research SI 71 122–130 Coconut Creek, Florida 2014 ____________________ DOI: 10.2112/SI71-015.1 received 12 February 2014; accepted in revision 24 July 2014. *Corresponding author: aslinda@nahrim.gov.my © Coastal Education & Research Foundation 2014 Coastal Erosion at Tanjong Piai, Johor, Malaysia Nor Aslinda Awang †* , Wan Hasliza Wan Jusoh ‡ , and Mohd Radzi Abdul Hamid † ABSTRACT Nor Aslinda, A.; Wan Hasliza, W.J., and Mohd Radzi, A.H., 2014. Coastal erosion at Tanjong Piai, Johor, Malaysia. In: Silva, R., and Strusińska-Correia, A. (eds.), Coastal Erosion and Management along Developing Coasts: Selected Cases. Journal of Coastal Research, Special Issue, No. 71, pp. 122–130. Coconut Creek (Florida), ISSN 0749-0208. Tanjung Piai, Johor, Malaysia, is a ramsar site, located at the southern-most tip of mainland Asia, and consists mainly of mudflats and mangrove forests. The coast has experienced severe erosion for several decades, in spite of the construction of various coastal defense structures. The reported rates of shoreline retreat were between 2 to 4 m/year. Hydrodynamic modeling using 2008 field data indicate that the maximum current speed observed along the east coast of Tanjung Piai ranges from 0.2 - 0.5 m/s, while the west coast experiences lower current speeds of less than 0.2 m/s. Strong currents occur at the tip of Tanjung Piai with a speed of 0.5 to 0.8 m/s. The simulation also indicates that some local current patterns are formed near the tip due to the presence of a small island as the flow entering the study area during flooding were reflected to the east while the flow during the ebb tide tend to move toward the opposite direction. Wave simulations show that most of the waves come from Singapore and the Straits of Malacca, with amplitudes of over 1.5 m, are reduced to less than 0.8 m as they travel towards Tanjong Piai coast. These local hydrodynamic conditions, combined with the existence of regular ship wakes, are believed to be the reason for the intensive erosion at Tanjung Piai. Model simulations incorporating the proposed coastal protection measures indicated positive and negative impacts of the hydrodynamic changes around the study area. The results shown that the magnitude of the current speed and wave height would be reduced in the area behind the structures but slightly increased on the other parts of the coast. These changes will determine the sediment transport movement in the area. Therefore, it is necessary to understand the hydrodynamic characteristics before implementing any kind of coastal protection measures because they may protect some area from erosion, but may not be favourable to the other parts of the coast. ADDITIONAL INDEX WORDS: Navigation, coastal inlets, numerical wave modeling, nearshore wave processes. INTRODUCTION Hydrodynamic forces, sediment supply and antecedent topography play an important role in the geomorphological conditions of coastal zones. In Malaysia, not many studies have been carried out around the Malacca and Singapore Straits in relation to the coastal hydrodynamics and geomorphology. The study area Tanjung Piai, Johor, is located at the southern-most tip of Peninsular Malaysia, with approximate coordinates of 1°15'50.64" N and 103°30'36.57" E (Figure 1). The local climate is strongly influenced by the two prevailing monsoons, i.e. Southwest Monsoon (June - September) and Northeast Monsoon (November - March) (Tkalich et al., 2002). Tanjung Piai is characterised by its mudflats and mangrove forests. It has a high diversity of mangrove species (22), which are ecologically important and a natural barrier to protect the inland villages and agricultural lands from extreme wave events, including tsunamis. It is also an important habitat for migratory and resident birds, which includes the International Union for Conservation of Nature (IUCN) Listed Vulnerable Species, the Lesser Adjutant Stork. It is part of the Important Bird Area (IBA) of South-west Johore, which extends from Parit Jawa to Tanjung Piai. Due to its geomorphology and diverse species of fauna and flora, Tanjung Piai was declared a Ramsar Site (under the Convention of Wetland, Ramsar, Iran 1971) in 2003 (Azlan and Othman, 2009; KNB, 2012). The mangroves provide a range of valuable benefits to local communities, local businesses and the wider economy of Johor, as well as to the global society (KNB, 2012). Tanjung Piai has a high socio-economic value for eco-tourism and fisheries. The site attracted 32,000 visitors in 2006 (Wetland International and Johor National Park Corporation, 2007). In fact, it is a national icon, being the southern-most tip of mainland Asia and is a priority site for national eco-tourism, being the third designated park of Johor National Park Corporation. Coastal Issues and Human Interferences The mudflats and mangrove forests of Tanjung Piai have been eroded significantly over the years. It was reported that the erosion at the east coast of Tanjung Piai had taken place since at least the 1930’s. Similarly, the western coast of Tanjung Piai was also facing critical erosion with an estimated rate of about 2 - 4 m/year (Abdullah, 1992). The erosion escalated rapidly after the dredging of a navigation channel in 2002 (DID, 2013). Figure 2 presents a shoreline comparison between 1974 † National Hydraulic Research Institute of Malaysia Ministry of Natural Resources and Environment Selangor, Malaysia ‡ School of Environmental and Natural Resources Science Faculty of Science and Technology National University of Malaysia Bangi, Selangor, Malaysia www.cerf-jcr.org www.JCRonline.org