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Malaysia Water Research Journal<br />
PHYSICAL HYDRAULIC MODELLING FOR THE DEVELOPMENT<br />
OF INNOVATIVE COASTAL PROTECTION STRUCTURE IN A 2-D<br />
WAVE FLUME<br />
Ahmad Hadi Mohamed Rashidi (1) , Mohamad Hidayat Jamal (2) , Mohd Radzi Abd<br />
Hamid (3) & Siti Salihah Mohd Sendek (4)<br />
(1,3,4)<br />
Research Centre for Coastal and Oceanography. National Hydraulic Research<br />
Institute of Malaysia,<br />
Ministry of Natural Resources and Environment, Selangor, Malaysia<br />
(2)<br />
Faculty of Civil Engineering & Centre for Coastal and Offshore Engineering<br />
Universiti Teknologi Malaysia, Johor, Malaysia<br />
ahmadhadi@nahrim.gov.my; mhidayat@utm.my; radzi@nahrim.gov.my;<br />
sitisalihah@nahrim.gov.my<br />
ABSTRACT<br />
NEXC Block is an innovative shore protection structure which is designed to<br />
protect the coast from severe erosion during monsoon season. While on a<br />
calmer period, the system encourages sediment accumulation thus expanding<br />
the beach naturally. NEXC Block is placed within Mean Higher High Water and<br />
Highest Astronomical Tide water level with sufficient toe protection for stability and<br />
efficiency, ensuring minimum adverse impact to existing coastal hydrodynamic.<br />
This paper aims is to present the development process of NEXC Block in 2-D<br />
wave flume facility, where site measurement works are conducted for data<br />
validation and monitoring. Model dimension and hydrodynamic parameters<br />
are geometrically downscaled to 1:20. Two slope gradient values are used<br />
representing actual beach profiles at selected sites. Cohesive-form sediment size<br />
is 100µm. Three water levels; Mean Lower Low Water, Mean Sea Level and Mean<br />
Higher High Water with two significant wave height values Hs (irregular waves)<br />
are used for simulations. Beach profile is measured both before and after each<br />
simulation for erosion-accretion and stability analysis. Simulation on exposed<br />
beach without structure is also carried out as reference profile. The experiment<br />
shows that NEXC Block model structure installed with ample toe protection is<br />
a stable coastal protection structure. The structure is able to withstand strong<br />
wave impact during monsoon; no significant structural movement was<br />
detected. However scouring is prevalent at the toe of structure at unprotected<br />
structures. Some parts of NEXC Block and toe protection are exposed during<br />
monsoon season but less sediments are found eroded as compared to exposed<br />
unprotected beach; in which maintaining beach stability. Moreover during a<br />
longer calm period, the sediments are found to return back to the beach hence<br />
nourishing and expanding the beach naturally.<br />
Keywords: Shore Protection, Hydraulic, Physical Model, Coastal Erosion, Natural Beach Accretion<br />
28<br />
Institut Penyelidikan Hidraulik Kebangsaan Malaysia (NAHRIM)<br />
National Hydraulic Institute of Malaysia (NAHRIM)