27.9 millimetres of rain has fallen in Grahamstown in the past two days, according to the Rhodes University weather service. This is coupled with high humidity levels of around 90%.
27.9 millimetres of rain has fallen in Grahamstown in the past two days, according to the Rhodes University weather service. This is coupled with high humidity levels of around 90%.
5.5mm fell in Grahamstown between 4 and 10 October. Very heavy rainfall and flooding was reported in Port Alfred on Thursday. Heavy rainfall fell over many sections of Grahamstown like William Street, Phaphamani, Zolani and Extension 6.
William Street had to be cordoned off as a result of the heavy rains. According to Nikki Kohly and Roger Rowswell, the last time such heavy rain was recorded within a 24 hour period was in February 2009, when 48mm fell.
Prior to that, 50mm fell in April 2008 and 67mm in March 2007.
"It is the lack of these high daily rainfalls that have contributed to water courses drying up," said Rowswell. The highest monthly rainfall since 2006, was in February 2009, where 185mm was recorded, followed by December 2007 with 115.7mm and January 2008 with 116.5mm.
The last good wet month was October 2009 with 127.8mm. According to Rowswell and Kohly, 2006 was a wet year, where 1160mm had fallen, which equates to an average of 96.7mm per month.
Rowswell's rainfall measurements found that five of the 12 months recorded rainfalls of over 100mm, with August having the highest (276mm) and May having the lowest of the five wet months with 102mm. The subsequent three years then produced less than average yearly rainfalls.
"Recent annual rainfall figures – in 2007 (688.4mm), 2008 (664.8mm) and 2009 (705.6mm) – are all below average," said Rowswell. Rowswell further said that in recent years, even though rainfall amounts have been below average, the storage dams have received good inflow due to runoffs.
"In 2005 annual rainfall was 709mm (below average) 77mm was recorded over three days, 5 to 7 November. In August 2006; 88mm fell on the third and 58mm on the 25th," said Rowswell.
However, he said that further heavy rains are needed to keep the storage dams at optimum levels. "In August 2002, 206mm fell within six days and then on 11 September, 7mm over three days. It is this type of rainfall that Grahamstown requires to fill our catchment dams."
