mag

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