Flooding in parts of Joburg

According to motorists in Alberton, most roads were flooded in the south of Johannesburg and surrounding areas after the heavy downpour yesterday afternoon, reports the Comaro Chronicle.

More rainfall is predicted for Johannesburg on Friday afternoon.

There was flooding in Glenvista and motorists were advised to seek alternative routes if the road they were driving along looked flooded.

Some vehicles were submerged and roads were impassable.

Danger zones included: Hart, Jacqueline, Michelle, Swartkoppies, Hennie Alberts and the bottom of Comaro and Bellairs.

Meanwhile in Krugersdorp on the West Rand, Arrive Alive warned road users to drive extra carefully after a major rainstorm hit the area at about 3.30pm on Thursday, reports the Krugersdorp News.

They said that roads in the area could become flooded as the cloud burst caused a lot of rain to fall in a short amount of time. Thunderstorms have also been reported in the area.

They listed the dangers of flowing water over roads and low water bridges as follows:

• Flowing water applies pressure to contact areas. The higher the speed the higher, the pressure.
• With water that is one meter high it will flow out at a speed of 4,47 meters per second or 16 km/h. The pressure is one metric tonne per square meter.
• With a wheel half under water the area is 0,4 sq m and the force 0.4 tonne per wheel. For the four wheels it becomes one and a half tonnes and for 2m of water it becomes 2 tonnes per sq m.
• Be careful, water that has fallen only 0,4m reaches a speed of 3,2 km/h and can sweep your car off a road bridge.
• When the side of the body of a vehicle makes contact with the water the force increases rapidly but the water now also acts on the underside of the vehicle as well and starts to lift it. It is now able to float like a ship. The weight of the vehicle will not be able to hold it on the road. Every cubic meter of space in a vehicle can lift one tonne.
• Be careful, 0.6 meters of water can float a car. Only vehicles that are open and let the water through will behave differently.
• Establish the body area of the vehicle and its mass. From this, calculate the how deep the vehicle will sink in the water before it floats.
• For a truck that is 8.5 metres long and 2.5 metres wide, with a mass of 12 tonne it will float at a level of 0,532 meters above the body base and be able to float down the river.

– Caxton News Service