Scientists are closely monitoring KwaZulu-Natal's tides in anticipation of the moon, the sun and the Earth's alignment on March 18, which will see the greatest gravitational pull on the earth in about 18 years.
But while this alignment could result in dramatic high tides and has people living along the coast bracing themselves for tsunami-like sea conditions, an expert has said that unless these tides coincide with a storm at sea, the effect of the gravitational pull could be minimal.
The lunar eclipse, which took place at the weekend is an indication that the three bodies are moving into line with the Earth obscuring the sun and casting a shadow on the moon.
'The gravitational pull of the moon, counteracting each body's force on the Earth'
Andrew Mather, the eThekwini Municipality's Project Executive for Coastal Policy, explained that the surface of the Earth, especially its water, is influenced by other bodies in the solar system, particularly the sun and the moon.
"While the moon is spinning around the Earth, the Earth is revolving around the sun in turn and, because the moon does not orbit the Earth in a straight plane, the Earth, the moon and the sun are not always in alignment," he said.
The three bodies only align horizontally every 18.61 years and, when this occurs, the gravitational pull on the earth is at its maximum.
Mather explained that the moon orbits the Earth on a tilting axis, moving up and down, almost with a see-saw effect, and the gravitational pull of the sun usually opposes the gravitational pull of the moon, counteracting each body's force on the Earth.
This accounts for the "normal" tide levels. However, when the forces of both bodies are pulling on the Earth in the same direction, the highest variation in the tides occurs.
Although this alignment is due to take place on March 18, Mather said the delayed response of the gravitational pull would mean that KwaZulu-Natal's tides would only be affected on March 20 at approximately 4.30am.
Mather's tide predictions showed that the high tide would be approximately 2.19m at this time, an increase of about 10 percent on the usual height. The high tides experienced in March and October last year reached a maximum of 2.18m and 2.16m respectively.
However, Mather cautioned that people need not be too concerned as this increase would not necessarily have a huge effect on the waves and would hardly be noticeable when looking at them.
Areas that would be mostly affected would be La Lucia, the Umhlanga beachfront, St Michaels and possibly the Durban beachfront, he said.
By Bronwyn Gerretsen
Source: Pretoria News
