HULHULE-MALE’ BRIDGE PROJECT

EIA for the proposed Hulhule-Male’ Bridge Project
4.2 Hydrology
4.2.1 Tidal Pattern
Tides in the Maldives are mixed and semi-diurnal/diurnal. Water levels at the site vary mainly in
response to tides, storm surge or tsunamis.
Tidal variations are referred to the standard station at Hulhulé Island. Typical spring and neap
tidal ranges are approximately 1.0 m and 0.3 m, respectively (MEC, 2004). Maximum spring
tidal range in Hulhulé is approximately 1.1 m. There is also a 0.2 m seasonal fluctuation in
regional mean sea level, with an increase of about 0.1 m during February to April and a decrease
of 0.1 m during September to November. Table 4.4 summarizes the tidal elevations reported at
Hulhulé, which is representative of tidal conditions at the project site.
Table 4.4: Tidal Variations at Hulhule International Airport
Tide Level
Referred to Mean Sea level
Highest Astronomical Tide (HAT) +0.64
Mean Higher High Water (MHHW) +0.34
Mean Lower High Water (MLHW) +0.14
Mean Sea Level (MSL) 0.00
Mean Higher Low Water (MHLW) -0.16
Mean Lower Low Water (MHLW) -0.36
Lowest Astronomical Tide (LAT) -0.56
The tidal levels were simulated for the project site based on the tidal data from Hulhule’. The
results are presented in Table 4.5. Based on these results, the spring tide range is about 0.90 m
measured during spring tide; the design highest level of 10% of cumulative frequency of high
tide is 0.55 m, the design lowest level of 90% of cumulative frequency of low tide is -0.51 m;
within 300 years, the high tide level is 0.78 m, the low tide level is -0.83 m and the tide range is
1.30 m.
Table 4.5: Design tide levels and tide ranges with different recurrence intervals in tide station of
Airport Island (PIII)
Recurrence interval (years) High tide level (m) Low tide level (m) Tide range (m)
300 0.78 -0.83 1.30
200 0.77 -0.82 1.29
100 0.76 -0.80 1.27
50 0.74 -0.78 1.25
20 0.72 -0.75 1.22
10 0.70 -0.72 1.19
2 0.63 -0.63 1.12
Prepared by: CDE Consulting & China Shipping Environment Technology Page| 60