Cape Town water crisis: above-average rainfall hit by huge usage spike

November has been a rather wet month for some areas of the Western Cape, but that doesn’t mean Cape Town’s dam levels have benefited entirely.

Due to a spike in water consumption and warmer temperatures, dam storage remains flat this week according to the City of Cape Town’s dam level report (pdf).

Total storage capacity now stands at 36.1%, down from 36.2% the previous week.

Digging deeper into the report, the City notes that four of the six dams in the Western Cape Water Storage System gained capacity this week.

The Berg River Dam added just 0.1% to its coffers, and is now back up to 66% full. The Voëlvlei Dam also gained 0.2%, to stand at 26.9%.

The Steenbras Lower Dam (55.2%, up from 54.4%) also gained, partly due to the Upper Dam’s consistent 100% capacity.

The biggest loser, yet again, was the Theewaterskloof Dam. The largest dam in the system — holding more than 52% of Cape Town’s surface water storage — declined by 0.5%. That’s a drop of 2.4-billion litres, or around four days of water at Cape Town’s current consumption rate.

For Cape Town’s minor dams, just two of the eight dotted around the metropole saw a marginal increase in capacity this week. And we mean marginal — the biggest gainer was Simon’s Town’s Kleinplaats Reservoir, adding just 0.3% to its potential 1.3-billion litre store.

But not all is doom and gloom.

November sees above-average rainfall

Thanks to bountiful rains over 20 and 21 November, the Wemmershoek Dam gained 1.7% over the previous week, breaching the 51% mark for the first time this season.

The dam’s catchment area received just less than 60mm of rainfall during this period — close to double its average long-term rainfall for the entire month. In total, it has received 75.2mm of rain since 1 November.

Other areas across Cape Town have also bested November’s long-term rainfall average figures.

The Steenbras catchment area received 67.5mm this month, surpassing its long-term average of 46mm. The Voëlvlei Dam received more than 40mm this month, as opposed to the normally recorded 25mm.

Other monitored areas, including Tygerberg, Brooklands, Table Mountain’s Woodhead Dam and Wynberg have also breached their November averages.

And yes, even the Theewaterskloof is nearing its long-term average rainfall figures for November, recording 34.6mm of rainfall this month.

Water consumption spikes

But good rains have been drastically offset by a spike in water consumption across the metropole.

Two weeks ago, Cape Town residents reduced consumption to 580-million litres per day. This week, that figure has ballooned to over 630-million litres — the highest recorded figure since April 2017.

The City of Cape Town is this week mapping the Cape Flats aquifer, in addition to drilling abstraction boreholes into the Table Mountain Group aquifer near Steenbras Dam.

The @CityofCT welcomes all tourists to Cape Town but we urge and encourage visitors to help us save water in this drought crisis pic.twitter.com/wnn3XajplH

— Patricia de Lille (@PatriciaDeLille) November 27, 2017

Cape Town Mayor Patricia De Lille confirmed that water extraction from these aquifers — which in total should supply more than 100-million litres per day to the city — should be online by June 2018.

Feature image: Theewaterskloof Dam, April 2017, via City of Cape Town