Integrated coastal zone management to protect the Sarawak shoreline

Abstract

Coastal erosion along Sarawak shoreline is getting serious in recent years due to the impact of climate change and global warming. Strong waves had washed away the land along the shore or beach and thus threatens the infrastructures that were constructed along Sarawak shoreline. Department of Irrigation and Drainage had adopted many methods to protect the shoreline including seawalls, breakwaters, geotextile tubes, concrete mass Labuan blocks, amour rocks and etc. The cheapest and most economic protection method is using armour rock. Besides, amour rock was found to be strong, durable, long-lasting, able to absorb and dissipate the waves before hitting on the shore. However, appropriate size of amour rocks to protect the shore is unknown. Therefore, this research is carried out to determine the appropriate armour rocks sizes for protecting the shoreline against the waves along Sarawak shoreline. The design methodologies are including determination of tidal levels, design wind speed, wind set-up, wave period, sea level rise, wave set-up, breaker height and lastly design armour rock sizes range. Shoreline Protection Manual and Hudson’s formula were adopted in this research to determine the appropriate sizes range of armour rocks. The study area was subdivided into 7 regions. Results revealed that southern part of Sarawak shorelines requires larger armour rock sizes compared to the northern region. The nominal size ranges of armour rocks for regions 1 and 2 are found to be 2112 mm, 1734 mm for region 3, and 1173 mm for regions 4, 5, 6 and 7. Results also revealed that the required armour rock sizes increase with the increment of Mean High Water Spring, nearshore slope gradients and structure slope. Besides, results also concluded that smaller amours rocks is sufficient to react against smaller waves, while bigger waves required bigger rocks for protecting the shoreline.