#Tidal surge today series#

What is a spring tide?ĭespite their name, spring tides are regular occurrences throughout the year. This is usually on the order of tens of centimetres to one metre or so.Īs the cyclone approaches land, the water surface along the coast rises. Low pressure causes the sea surface to bulge upwards below the centre or eye of the cyclone, and the magnitude of this disturbance is related to the severity of the low pressure system – the deeper the low pressure cell, the higher the elevation of the sea surface. Storm surges are caused by a low pressure (cyclone) weather system approaching the coastline from the ocean. This is where the level of the sea surface near the coast is temporarily raised up and results in flooding along that coastal stretch. It is this combination that is the cause here, not these individual factors in isolation. Third, the coincidence of the storm with the period of high tide (a monthly event) and equinoctial high-high tide (a seasonal event). Second, low-pressure cells often result in strong onshore winds, and these can whip up the sea surface and create big waves which can potentially run further inland, especially when the sea surface is raised.

These happen very commonly but often don’t result in high amounts of flooding by themselves. First, a storm surge associated with low-pressure weather systems coming onshore. What drove the flooding?Ī critical combination of three factors resulted in this significant flooding. The Conversation Africa asked Jasper Knight, a geoscientist who researches coastal processes, to explain what happened. One person died cars, homes and businesses were damaged.

#Tidal surge today series#

A series of powerful tidal surges battered coastal areas in South Africa’s Western Cape, Eastern Cape and KwaZulu-Natal provinces over the weekend of 16 September.