Noraisyah, S.1, Parham, P.R.1, Mohd-Lokman, H.1, Rosnan, Y.2 ,Nor-Antonina, A.2 and Rokiah, S. 1

SANDY BEACH MORPHODYNAMIC CLASSIFICATIONS INDEX BASED ON WRIGHT AND SHORT (1984) AT SELECTED BEACHES ALONG TERENGGANU, MALAYSIA

Noraisyah, S.1, Parham, P.R.1, Mohd-Lokman, H.1, Rosnan, Y.2 ,Nor-Antonina, A.2 and Rokiah, S. 1

1Institute of Oceanography and Environment (INOS), Universiti Malaysia Terengganu,

2School of Marine Science and Environment, Universiti Malaysia Terengganu,

21030 Kuala Terengganu

*E-mail of correspondence author:

ABSTRACT

In a coastal region where there are large pressures on the beach resources through recreational usage, understanding the beach morphodynamic classification is paramount. On this basis, some selected beaches along Terengganu coastal region were chosen in order to determine its morphodynamic classification according to the indices modelled by Wright and Short (1984). As a result, the beaches at the northern and southern parts of Terengganu were classified as intermediate state while the middle part classified as reflective beach. Most of the beaches exhibited characteristics resulting from antecedent hydrodynamic conditions with stronger hydraulic forces at the middle region compared with the northern and southern beaches.

Keywords: Beach morphodynami classificationc, Wright and Short (1984), Terengganu.

INTRODUCTION

Beach classification can be useful for coastal planners to group beaches of similar characteristics and behaviours. Many beach classifications have been developed for a variety of wave and tidal conditions. The range of classifications was developed because beaches behave and evolve differently under various forces. These classifications were developed for sandy beaches. There is limited applicability for bedrock dominated coasts where behaviour and sand availability is governed by rock outcrops, coral reefs and headlands (Velardo 1998; Jackson et al. 2005). A classification was applied to classify the morphodynamic state of the eleven beaches studied. It describes the variability between the states by the relationships between wave forcing, sediment and beach slope characteristics.

MATERIALS AND METHODS

A classification according to Wright and Short (1984) was applied to classify the morphodynamic state of the beaches studied (Figure 1). It describes the variability between the states by the relationships between wave forcing, sediment and beach slope characteristics. Besides, the morphodynamic indices and parameters have been developed to distinguish between the beach states (Carter, 1988; Short, 1999). Parameter of swash slope (β) and median grain sizes (D50) (computed using GRADISTAT software) were also taken into consideration in order to classify the beach state (Carter, 1988; Short, 1999). These two parameters were then compared with the visual observation based on Wright and Short (1984) morphodynamic classifications to confirm the beach states occurred. Field data was collected in April, August and December 2008 (Figure 2).

Figure 1: Map of the Study Area

RESULTS AND DISCUSSION

From the data gained from swash slope and median grain sizes (Table 1), only swash slope met the criteria for morphodynamic classification based on visual classifications (Wright and Short, 1984). At the northern region of Terengganu, beaches of Kuala Besut (ST 1), Penarik (ST 2) and Merang (ST 3) were classified as intermediate state where the beach at Kuala Besut is likely to be a near-dissipative type. In the middle region however, beaches of Batu Rakit (ST 4), Seberang Takir (ST 5) and Teluk Lipat (ST 8) remained in a reflective state during the three respective months. The Kuala Abang and Kuala Ibai beaches were perched. Otherwise, most of the beaches at southern region of Terengganu were categorized as intermediate beaches with exceptional for Teluk Mak Nik (ST 11).

In this study, we concluded that beaches along the Terengganu coastal region are classified as intermediate and reflective morphodynamic state. The reflective beaches mostly occurred at the middle part of Terengganu due to steeper swash slopes as exposed by wave attack vulnerability. Along the central portion of the study area from Batu Rakit (Kuala Terengganu) to Teluk Lipat (Dungun), there is a diverse assortment of human activities and facilities. These consider that the beaches presently underutilized by the human interference which exclusively leads to erosion and steeper slope condition. These may explain the reflective morphodynamic character of this section of beach. Strong waves collapsing on the beachface during Northeast Monsoon were steadily increased the risk factor of beach hazard which resulted in substantial erosion (Benedet et al., 2004).

In the northern and southern portion of the study area, beaches were classified as intermediate although beaches at Besut (ST 1) and Teluk Kalung (ST 10) exhibited near-dissipative characteristics at certain time. The intermediate beaches are usually longer than the reflective beaches. Wave energy along these intermediate beaches produces rhythmic bars during December 2008 and low-tide terraces during April and August 2008. The beach profile of this type of beach is gentler compared to reflective beaches. This may due to the site specific and differential energy forces (lower) that influence this area at particular times. We conclude that state classification were very dependent on hydraulic forces that influence the beach area, Benedet et al (2004) and Tanya (2005).

REFERENCES

Benedet, L., Finkl, C. W. and Klein, A. H. F. (2004). Morphodynamic classification of beaches on the Atlantic coast of Florida: Geographical variablility of beach types, beach safety and coastal hazards. Journal of Coastal Research, 39:1-7.

Carter, B. (1988). Coastal environment: an introduction to the physical, ecological, and cultural systems of coastlines, New York: Academic Press.

Jackson, N. L., Nordstrom, K. F., Eliot, I. and Masselink, G. (2002). ‘Low energy’ sandy beaches in marine and estuarine environments: a review. Geomorphology 48 (1-3), 147-162.

Short A.D. (1999). Handbook of beach and shoreface morphodynamics. Chichester: John Wiley.

Tanya, S. (2005). Physical characteristics of Perth Beaches, Western Australia. Unpublished master’s thesis. University of Western Australia, Australia.

Velardo, S. (1998). Patrolled Sandy Beaches of Southwestern Australia: Characteristic Morphology and Public Hazards, Unpublished Honours Thesis, University of Western Australia.

Wright, L.D. and Short, A.D. (1984). Morphodynamic variability of surf zones and beaches: A synthesis, Marine Geology 56(1-4), 93-118.