Awaiting Day Zero: Cape Town Faces an Uncertain Water Future
South Africa’s second-largest city has pushed back the day when its taps are expected to run dry. But with its population growing and the climate warming, Cape Town, like many cities in semi-arid regions, must take decisive measures to meet its future water needs.
Backed by the iconic Table Mountain, Cape Town, South Africa’s second-largest metropolis, seduces increasing numbers of international travelers. Its charismatic neighborhoods, bright beaches, and breathtaking natural landscapes garner shelves-full of tourism awards and terabytes of glowing Instagram posts.
Recently, Cape Town also has become infamous as the home of “Day Zero,” the day when most of the city’s taps are predicted to run dry. With its major, rain-fed supply dams dangerously low after three years of drought, most of the city’s 4 million-plus residents — some rich, many desperately poor — have been facing the prospect of lining up at emergency water distribution points to collect a daily ration of just 6.6 gallons per person sometime before June or July. That’s when winter rains normally begin filling the reservoirs of this Southern Hemisphere city.
Now, largely thanks to radical conservation efforts — in January, the average Cape Town resident’s daily water quota was just one-third the amount used by the typical Californian at the height of that state’s 2016 drought — the city has reduced water consumption by 57 percent. Day Zero has been pushed back to July 9. And if the citizens of Cape Town (myself among them) continue to save as we have been, we should make it to the winter rainy season without having to line up for water.
So, disaster averted? Nothing to see here anymore? Far from it. The city’s efforts on the supply side of the water equation have been far less successful than its work on consumption. Even if the drought comes to an end in 2018 — and few experts are willing to predict that — the effects of this water crisis will be felt for years, possibly decades.
How did Cape Town, one of the best-managed and wealthiest cities in Africa, find itself on the brink of running dry?
Cape Town’s predicament provides a global warning about the difficulty of ensuring water resilience in a warming world, even if, as with Cape Town, climate change is firmly on the agenda of city managers. Most climate models predict that the Cape Town region will become not only warmer, but drier, which bodes ill for a metropolitan area whose population has roughly doubled to 4 million in the past three decades and continues to grow at 1 to 2 percent annually.
And Cape Town’s rushed efforts to boost water supply by tapping into aquifers, including some in national parks and provincial nature reserves, are damaging valuable ecosystems and putting rare species at risk of extinction. The agricultural sector, including the Cape region’s world-renowned wine industry, has been forced to sharply cut back on irrigation, which is reducing production and leaving tens of thousands of people out of work.
So how did Cape Town, one of the best-managed and wealthiest cities in Africa, find itself on the brink of running dry? The city has, after all, won awards for its work on climate change. South Africa has some of the world’s most detailed, progressive water laws and deep expertise in water science and management, climate science, and meteorology. The city has mapped projected sea level rise and convened countless climate change adaptation planning sessions. Last year, Cape Town’s mayor said, “We cannot plan anything without factoring in the impact of climate change.”
A simple (and perhaps simplistic) answer to the cause of the current crisis is that rainfall was well below average for three years in a row, that no one could have or did predict that, and thus serious action to reduce water consumption — which should have begun in 2016 — came too late. The crisis has exposed significant weaknesses in scientists’ ability to forecast weather on a seasonal scale, which is when it matters to city managers and farmers, and predict rainfall on an annual or decadal scale, which is when it matters to developers of large-scale infrastructure, such as raising dam heights and building desalination plants.
The southwestern part of South Africa has a Mediterranean climate much like the central coast of California, with hot, dry summers and cool, rainy winters (June through August.) The winter rains fill the six large dams around the city that form the core of the Western Cape Water Supply System (WCWSS), which services the vast majority of the city’s residential and industrial water users, as well as farming areas and smaller towns nearby.
The winter rains are generally very reliable. Using historical rainfall data, Piotr Wolski of the Climate Systems Analysis Group at the University of Cape Town has determined that a multi-year drought as severe as the current one would only be expected once every few hundred years, perhaps less than once in a millennium. The ongoing drought in the catchments of the WCWSS dams, he writes, “is indeed very, very rare, and thus very, very severe.” The historical rainfall record indicates that, having had two poor rainfall years in a row (2015 and 2016), the chances of a third bad year – especially one as bad as 2017 – were extremely remote.
In addition to historical data pointing to the extremely low likelihood of 2017’s winter being dry, the South African Weather Service modeled a three-month seasonal forecast for the winter of 2017 that predicted higher than average rainfall.Notwithstanding that seasonal rainfall forecasts for the Cape region are notoriously unreliable, it appears that officials were left feeling less urgency to impose hugely unpopular water restrictions or push forward with expensive water infrastructure projects early in the year.
Experts have long warned that Cape Town would find itself in a water crisis caused by converging drought, population growth, and the failure to secure new water resources. But because of uncertainties in water consumption rates and in weather and climate prediction, it’s been hard to fix a date.
The city’s water consumption has fallen from 317 million gallons per day in early 2015 to about 137 million gallons per day.