Port Elizabeth of Yore: The 1968 Flood in Numbers

Harrowing accounts of what people endured over four hours on the Sunday morning, 1st September 1968 are recounted, as they should be, every Spring Day on radio and in the local newspapers. Needless to say, they are tragic and terrifying.  To put this flood into perspective, this flood will be interrogated not from a human drama viewpoint but rather from the perspective of rainfall, isohyet charts and comparisons with subsequent floods

On Sunday 1st September 1968, a ferocious storm hit Port Elizabeth when more than 40cms of rain fell in just four hours, wreaking havoc, damaging some of the city’s most prominent buildings and infrastructure and killing nine people.

Main picture: Flooding in the Baakens Valley

Rainfall intensity

When the residents of Port Elizabeth awoke on the morning of Sunday 1st September 1968, it was overcast with a little drizzle, just sufficient to compel them to stay in bed. Not so for my father and his brother Bryce McCleland who as a “religious ritual” went fishing at 4am every Sunday irrespective what the weather was like. For more sane individuals, the weather was the justification to sleep late.

Many were rudely awakened when just before 8am as the heavens opened, like a storm of Biblical proportions. In just over 4 hours, between 07h40 and 12h00, a total of 352 mm of rain was measured at the Port Elizabeth Airport. Although this is the officially documented figure, the autographic rain gauge at the reservoir in Brunswick Road (Adcockvale) recorded 470 mm between 08h00 and 12h00.

This equated to a sustained rainfall intensity of 20 to 30 mm per 15-minute period, over this 4-hour period. This turned roads and streets into raging rivers that caused wave upon wave of destruction. It was pointless castigating the City Planners as none would gave designed a stormwater system that could even vaguely cope with this volume of water. Experts claim that this was a flood with a return value of more than 100 if not 1000 years (i.e. it would only occur once in 100 if not 1000 years).

By the end of the day, the airport had recorded 429 mm and the Adcockvale Reservoir 552 mm. Experts claim that approximately 26 000 Megalitres of water was deposited over the city. That equates to almost the entire Churchill Dam (33 000 Megalitres) being poured over the city in four hours.

The rainfall chart for the period 07h30 to 12h30, paints a clearer picture of the actual intensity of the rain (note that the gauge syphons when it reaches 10 mm).

Rainfall Chart for PE Airport on 1st September 1968

Rainfall rate

To put this into context, the following is a running total of the hourly rainfall:

09h00

By 09h00 a total of 82.9 mm of rain was measured (in one hour the rain exceeded Port Elizabeth monthly average rainfall of around 50 mm).

10h00

By 10h00 a total of 161.1 mm was measured (in two hours the rain exceeded the 24-hour rainfall total of 128 mm, that was measured at the Port Elizabeth Airport, during the devastating flood of 2 August 2006).

11h00

By 11h00 a total of 265.0 mm was measured (in three hours the rain exceeded the total 24-hour rainfall total of 224 mm, that was measured at the Port Elizabeth Airport, during the devastating flood of 25 March 1981).

12h00

By 12h00 a total of 352.0 mm was measured (in four hours the rain exceeded the monthly total of 309 mm that was measured at the Port Elizabeth Airport, for the entire month when flooding occurred in March 1981).

Comparison with subsequent floods

By comparison, the 1968 flood far exceeded other floods in so far as not only sustained extreme rainfall intensity is concerned, but also total rainfall. The graphic below shows the comparison between the rainfall intensities of the September 1968, March 1981, December 2004, May 2006 and August 2006 flooding events in Port Elizabeth, over a 5-hour period. It is clear that 1968 is by far the worst flood in living memory.

Rainfall variability

It is interesting to note that just like the 1908 flood, the intensity and total rainfall varied in different parts of the city. In The South African Weather Service Publication, Caelum, (which contains a record of severe weather events in South Africa), the entry for November 1908 states that “The Baakens River flooded when a cloud burst struck between the farms of Messrs Parkins and Lovemore. At one stage the river rose 2 m in 5 minutes and in some places measured 7 m in depth”. It is interesting to note that the area referred to is the area between Lovemore Heights and Hunters retreat, which is roughly now the area of Sherwood and Lorraine. On that day in 1908, Emerald Hill only measured a total of 180 mm (52 and 158 mm) for the event. Photographic evidence shows that this figure was far exceeded.

The graphic below of the 1968 event shows that the majority of rainfall fell in the Sydenham/North End area, which ties up with where most of the damage was caused. Unconfirmed reports were published of a ship in the bay (just off the old North-End beach) recording in excess of 1000 mm.

Loss of Life

It was amazing, considering that so much rain fell, that only nine people were reported to have died as a direct result of the flood (some reports claim the total was 11). Eight drowned and one was electrocuted while trying to repair a roof leak of a house in Central. In another tragic incident, a father and his daughter were drowned after they were trapped beneath a parked car in Russell Road. The Provincial Hospital reported treating 55 patients at its casualty section.

Would it not be an act of remembrance if the names and details of the deaths of all nine fatalities were known?

Damages

At the time it was reported that damage was estimated to be in the region of R40 million. A projection of the rand value in 1993 (25th anniversary of the event) was put at R604 million. A 2018 projection of the rand value is more than R5 billion. However, one must consider the size of the city at that time and the total population. In other words, if this had occurred in 2018, with the current population, that figure could be, at a conservative estimate, quadrupled.

Mitigating factor

The fact that most of the population remained indoors, was one of the main reasons for the relatively low number of fatalities, for a disaster of this proportion. In 1968, most people were either asleep or preparing for church, when the rain started. Those who did decide to make the trip to church did not travel far, as at the time most attended a church within their suburb.

As my father and his brother were fishing at Schoenmakerskop which was only subject to light rain, it was only when my father dropped his brother off in Walmer, did he realise that a major rainstorm was in progress. As the Third Avenue Dip was awash, he had to backtrack to Circular Drive as most crossroads through Fairview were impassable.

Although the 1968 event was not fully forecast, modern technology and know-how would have foreseen such an event and the population would have been warned well in advance. Schools and other institutions would usually be closed during such an event, thus keeping many people off the roads.

Sources

Facebook: Ex PE 60’s 70’s 80’s’https://www.algoafm.co.za/article/local/96515/50th

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