Thunderstorms and flooding in South Africa
Thunderstorm season has arrived in Johannesburg, South Africa. These electrically charged storms are a welcome addition to the Highveld - adding important nitrates to the soil as a natural fertilizer.
While the theatre of the sky entertains and enthralls us, closer to earth calamity and chaos ensues as stormwater drains flood.
Urban stormwater pollution and flooding
The effects of urban flooding can be server. The flooding is caused by nonporous surfaces like tarmac and asphalt that do not allow rainwater to be absorbed into the ground. The excess water then flows into drains.
Stormwater drainage systems are not able to handle the qualities of water flowing into them and are often clogged with litter, hence the flood.
Other effects of flooding in most cities' drainage networks filter into metropolitan streams, rivers and lakes. These natural or man-made water bodies cannot handle the excess water and often flood too. The flowing water also results in soil erosion and damage to aquatic life.
Nonpoint source population
As the water flows it cleans the city, taking with it all the pollution and litter down into the gutters. This then flows into the ocean and is known as nonpoint population. This includes pesticides, fertilizers as well as oil, grease and toxic chemicals.
So the flood proverbially steals the rainy season's thunder…
In order to live in happier healthier cities, urban-jungle-dwellers should use permeable surfaces instead of concrete. Lawns, gravel surfaces and green parking lots allow for rainwater to be absorbed into the ground taking the pressure off drains and reducing.
BERA BV has developed a cradle-to-cradle certified gravel stabilization product, BERA Gravel Fix that reduces urban flooding and lessens stone loss when it rains. An added benefit is rainwater is restores the groundwater supply.