Erda Khursyiah Basir Bernama 22 Sep 16;
KUALA LUMPUR, (Bernama) -- The "king tide" that pounded coastlines in the west coast states of Peninsular Malaysia earlier this week and caused flooding in various areas took many people by surprise.
And, today, the Drainage and Irrigation Department warned that the exceptionally high tide is expected to return next month.
Since these high tides, also commonly referred to as king tides or spring tides, can be forecast, perhaps it is time for the relevant government agencies to put in place an early warning system so that coastal villagers are placed on alert for bigger-than-usual tides and possible flooding.
FORECAST
Head of Physical and Geological Oceanography Laboratory at Universiti Malaysia Terengganu's Institute of Oceanography and Environment Asso Prof Dr Mohd Fadzil Mohd Akhir said although the Malaysian Meteorological Department could forecast king or spring tides and also the height of the sea level, the recent phenomenon took everyone by surprise due to the unexpected weather conditions.
"The high-tide phenomenon is predictable and it occurs every year... but this time in the west coast, the high waves were accompanied by strong wind and heavy rain, which caused the sea water to overflow and flood some of the coastal villages. The wind is an important factor because the rough sea can cause waves to rise in height and sea water to spill over (low-lying areas)," he explained.
Mohd Fadzil said the recent phenomenon in the west coast had opened the eyes of the authorities and made them more aware of the dangers inherent in coastal areas during the high-tide season and inclement weather.
He added that the king tide phenomenon was common in countries like Vietnam and Indonesia, as well as in some parts of China where the tidal bore phenomenon was a tourist attraction. (A tidal bore, which occurs along a coast where a river empties into the sea, is a strong tide that pushes up the river, against the current.)
"The king tide phenomenon is also common in the United States and United ingdom... in fact, statistics have shown that in the last 10 years, there had been an increase in tidal flooding," he told Bernama.
STRONG GRAVITATIONAL PULL
According to a Bernama report, as of yesterday a total of 1,089 residents from various areas on the west coast that were hit by the high-tide phenomenon were evacuated to several relief centres.
Science, Technology and Innovation Minister Datuk Seri Madius Taugau was reported to have said yesterday that strong southwesterly wind of between 40kmph and 50kmph and strong waves that reached a height of 3.5 metres had contributed to the rising sea level during the high-tide phenomenon.
He also said that the ongoing southwest monsoon, the full moon and the moon orbiting closest to Earth (a state known as perigee) were other causes for the rising sea level.
Institute of Ocean and Earth Sciences (IOES) deputy director Prof Datuk Dr Azizan Abu Samah concurred that the effects of the recent high-tide phenomenon were compounded by the strong southwesterly wind.
He explained that what had occurred was a spring tide, which was usually caused by the gravitational pull of the full moon or new moon.
"When the phenomenon occurred (in the west coast of Peninsular Malaysia), we had just entered the full moon phase. But this time the strong southwesterly wind made the situation worse," he said.
DIURNAL TIDAL CYCLE
According to Azizan, king tides (that are higher than spring tides) occur when the Earth was in alignment with the moon and the sun.
"King tides can cause the sea level to rise very high and cause serious flooding, as had happened in Terengganu and Sarawak previously," he said.
Touching on the diurnal and semidiurnal tidal cycles, Azizan said the diurnal tidal cycle could also cause waves to rise higher and cause flooding, as was the case in December 2014 when the east coast states were hit by severe floods.
(The diurnal tidal cycle, which occurs in June and December, is characterised by a single high tide every 24 hours, while the semidiurnal tidal cycle, which occurs in March and September, is characterised by two high tides occurring daily about 12 hours apart.)
Since the authorities could forecast high tides, Azizan suggested that the public check out websites like www.tide-forecast.com to get the relevant information on king tides or spring tides.
In Sarawak, the state Department of Irrigation and Drainage's website provides information (such as date, time and predicted tide level) on king tide periods for the whole year.
The information is obtained from the Sarawak Government Almanac (an annual calendar containing important dates and statistical information such as astronomical data and tide tables), based on the computations by the Sarawak Marine Department.
-- BERNAMA
