HULHULE-MALE’ BRIDGE PROJECT

EIA for the proposed Hulhule-Male’ Bridge Project
4.2.2 Waves
There are two major types of waves observed along the islands of Maldives. The first type is
wave generated by local monsoon wind with a period of 3-8 seconds and the second type is
swells generated by distance storms with a period of 14-20 seconds [Kench et. al (2006), DHI
(1999), Binnie Black & Veatch (2000), Lanka Hydraulics (1988a & 1998b)]. The local monsoon
predominantly generates wind waves, which are typically strongest during April-July in the
southwest monsoon period. Wave data for Male and Hulhulé’ between June 1988 and January
1990 (Lanka Hydraulics 1988a & 1998b) shows that the maximum significant wave height (Hs)
recorded for June was 1.23 m with a mean period (Tm) of 7.53s. The maximum recorded Hs for
July was 1.51 m with a Tm of 7.74s. The mean wave periods were 5.0 – 9.0s and the peak wave
periods were within 8.0 – 13.0s.
Maldives experiences occasional flooding caused by long distance swell waves that are
generated by South Indian Ocean storms (Goda 1988). The swell waves of height 3 meters that
flooded Male’ and Hulhulé’ in 1987 are said to have originated from a low pressure system off
west coast of Australia (refer the next section for more detail). In addition, Maldives has recently
been subject to an earthquake-generated tsunami reaching heights of 4.0m on land (UNEP,
2005). Historical wave data from Indian Ocean countries show that tsunamis have occurred in
more than 1 occasion, most notable has been the 1883 tsunami resulting from the volcanic
explosion of Karakatoa (Choi et al., 2003).
The proposed site is partially exposed to wind generated waves during SW monsoons and during
transition periods (See Figure 4.11). Being located on the SE rim of the atoll rim, the site is
generally protected from the NE monsoon wind waves.
Waves studies around Maldives have identified the presence of swell waves approaching
predominantly from a southwest to a southerly direction Kench et. al (2006), Young (1999),
DHI(1999), Binnie Black & Veatch (2000) and Naseer (2003). The proposed site is exposed to
swell waves approaching from the SE. These waves approach and penetrate the reef pass
between Male’ and Hulhule. The timings of these waves usually coincide with SW monsoon and
occur between May and September with peak periods between June to August (See Appendix
F).
Waves generated from abnormal events could also travel against the predominant swell
propagation patterns (Goda, 1998), causing flooding on the eastern and southern islands of
Maldives (UNDP, 2009).
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