I think it is a symptom of all the development in the catchment area. With all the new housing estates going up in the area, more hard surfaces means less water penetration into the soil and larger, more spectacular flash floods. According to the SA Weather Service, this storm is in a band coming from the north, through Botswana and North West. Water flowing through water courses caused the Monument Dam at Key West Shopping Mall to overflow, spilling millions of litres into a nearby school, which had to be closed, while the water rushed through various parts of the town.
Watch this short video.
For the past three weeks, we've been having afternoon thunderstorms with 30mm on most days, but the whopper was on Saturday night and early Sunday morning, when my rain gauge over-flowed, meaning more than 100mm in just over 18 hours. I didn't write it down, but my estimate is 450mm for the month. My chickens sought the safety of the coop, not venturing out until it had all subsided after lunch-time.
I've always wanted to live either at the beach or the banks of a river, but Mother Nature is so unpredictable these days, I think for the moment I will settle for the high, flat plains of Gauteng.