Beach Morphology Changes during the Northeast and Southwest Monsoons at Mantanani Besar Island, Sabah (Malaysia)

Abstract

Mantanani Besar Island is a tourism and island that also has communities and is located in the west coast of Sabah. The island coastline is dominated by sandy beaches that tend to change due to direct exposure from natural phenomenon (waves, wind, current and periodic storm) and anthropogenic activities. The seasonal monsoon (NEM and SWM) is an important factor that intensifies the natural phenomenon leading to major beach changes in a short period of time. Therefore, this study aims to determine the beach morphology changes (profile, width, angle and volume) and to identify short-term beach changes trends at different seasonal monsoons. This study was conducted annually between 2013 and 2015. Beach profiling and field measurements were done in May and November 2013, March and September 2014 and January and May 2015 at 5 selected stations around Mantanani Besar Island. Further analysis of beach width, angle and volume were calculated based on beach profile data. The result of beach profile shows St. 1, St. 2 and St. 5 undergoing erosion while St. 3 and St. 4 are experiencing accretion. Averages of beach morphology were higher during the NEM than in SWM indicating more sediment accumulation on the beach of Mantanani Besar Island during the NEM and vice versa in SWM. The findings of this study are useful for local communities, tourist operators and the local government as a guide for any development and to produce shoreline management plans for Mantanani Besar Island.