SANDY BEACH PROFILE EVOLUTION

Abstract

Erosion and accretion of beach profile mostly occur on surf and swash zone. Beach profile evolution is affected by tide, wave, beach material and slope. However, rainfall and groundwater level may also affect the profile changes. Low groundwater level during dry season enhances infiltration of seawater into the beach hence increase the potential for accretion while high groundwater level during wet season saturate the beach and will potentially contribute to beach erosion. In Malaysia, the Northeast monsoon (wet season) carries more rainfall than the Southwest monsoon (dry season) hence this affect the groundwater level. Fieldworks were conducted at Desaru beach where three monitoring wells were installed perpendicular to the beach, together with a rain gauge and a tide gauge station in order to monitor the variations of groundwater levels, rainfall and tides. Fieldworks were conducted during low tides (ebb) on spring and neap tides about 4 to 6 times yearly starting on the year of 2013 to 2015. The results showed that beach profiles accreted on the dry season while eroded on the wet season. It is believed that the rainy season on Northeast monsoon cause the groundwater level to increase and enhancing erosion on the beach apart from the storm and high waves during the monsoon. Recent fieldwork also showed that the beach suffered massive erosion causing the shoreline to move landward and beach become steeper during the 2015 wet season. Due to that storm event, the beach profile was not getting back to its dry season profile as found in previous few years. It can be concluded that various process will affecting beach profiles on sandy beaches.