DROUGHT
Gauteng ’ s main dams explained
Alittle simple hydrological geography will make it plain to you which Gauteng ' s dams , ( notably the Vaal Dam ) aren ' t filling as fast as we ' d like because , while Gauteng is awash ( literally , if you were in Gillooly ' s Interchange a few weeks back ) with rain . The simple reason is because not much rain has fallen yet on their catchment areas . The Vaal Dam ' s catchment , for example , is largely the highlands around Standerton and Ermelo . Rain that falls over Gauteng flows west and north . Thus , insofar as Gauteng uses water from Roodeplaat , Bon Accord and Hartbeespoort Dams our rainfall is helpful to the dams , but that which falls on the south of the Witwatersrand ridge flows into the Vaal River , replenishing the Bloemhof Dam , thence into the Orange , and thus to the South Atlantic on the West Coast . Notably , rainfall in this area does not reach South Africa ' s largest dam , the Gariep , on the Orange River , as the
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the area that you use grey water on frequently , giving parts of your garden a break from receiving a constant dose of what is in effect a weak liquid chemical fertilizer . While “ proprietary ” grey water filter systems are now available , a handy smallholder could easily build a low-cost system comprising a gravel-and-sand filter and storage using 210 litre drums both for the filter and , in tandem for storage of the filtered effluent , the number of storage drums dependent on the size of the household . A more profitable use of grey confluence of the Vaal and Orange takes place further down the Orange at Douglas , northwest of the Gariep Dam . Rain which falls to the north of the Witwatersrand ridge flows into various northflowing rivers , notably the Crocodile River , and into Hartbeespoort Dam , and then into the Limpopo River on the Botswana border . The Limpopo , in turn , forms South Africa ' s northern border and , onward , the eastern boundary of Mozambique ' s Parque Nacional , before it empties into the Indian Ocean just west of Xai-Xai . Incidentally , many visitors to Gauteng wonder why , even in times of drought when other rivers might run dry , the Vaal River near Vereeniging and Van der Bijl Park is always full of water to the same level . That ' s because the river as it flows past those two towns is effectively a 64km long dam itself , its waters held there by the Barrage , a 10m high spillway across the river between Van der Bijl Park and Parys completed in 1923 .
WATER
water , perhaps , is to replace that ( fresh , clean , drinking quality ) water which flushes one ' s toilets , with grey water . Filtered and deodorised , grey water repurposed in this way will actually make a saving to overall water usage , rather than merely watering a small patch of plants and lawn . US plumbers ' studies show that an individual using an old-fashioned cistern toilet will use about 71 litres per day , while one using more modern water-saving devices ( including modern dual-flush systems ) will use about 35 litres a day .
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