Lessons from Cape Town's Drought

COMMENT RODGER BOSCH/AFP/GETTY

The narrow body of water that remained at South Africa’s Theewaterskloof Dam in May 2017. Lessons from Cape Town’s drought Don’t blame climate change. People and poor planning are behind most urban water shortages, argues Mike Muller.

ince May, winter rains have brought a looked set to be a long, hot summer, people received water for only two days a week. reprieve to the citizens of Cape Town, began to panic. Once the city’s reservoirs had been drained South Africa. The city had endured Municipal authorities told residents of clean water, the utility firm pumped and Ssevere drought for three years. Concerns that to slash their water consumption. For treated the polluted water that remained. In its water supply might run out in the summer suburban households, that meant going 2008, Barcelona in Spain had to ship water have been set aside, hopefully, for another from pre-drought usage of around 200 litres in from Marseille, France. During its dec- year. But the city remains vulnerable. per person per day to 50 litres per person ade-long ‘millennium drought’ in the 2000s, The situation was very different in 2013. per day (picture a bathtub filled to less than Australia spent billions of dollars on desali- Then, Cape Town had one of its highest 10 centimetres). Although many of their nation plants, most of which have not been annual rainfalls in decades. Reservoirs poorer compatriots regularly live with such used since. brimmed, and officials declared there was no a supply, suburbanites suddenly had to give It is important to learn from the experi- need to increase supplies before the 2020s. up their gardens and collect shower water to ences of Cape Town and elsewhere. Urban After another wet winter in 2014, the 6 main flush their toilets. The city more than halved growth means that many more places will reservoirs that feed the city were 97% full. its overall use, to just over 500 million litres face similar challenges as they compete with Then the drought began. Reservoir levels a day, and avoided ‘day zero’. surrounding regions for water. Big cities fell to 71% in 2015 and to 60% in 2016 (see Cape Town is one of several cities to see need to begin informed long-range planning ‘Cape Town drought’). When they reached its water supply fail in the past decade. In and to focus on minimizing risks from cur- 38% in 2017, at the beginning of what 2014 and 2015, parts of São Paulo in Brazil rent climate variability. Climate change adds

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SOURCE: CLIMATE SYSTEMS ANALYSIS GROUP higher tariffs. conservation, water-efficient appliances and in gardens and car washing, and promoted was introuble. City leaders banned water use 2016, for municipality the to realize that it took two winters, successive dry in2015and annual yield of 570million cubic metres. It cubic metres, compared with areliable hold less than 2 years’ supply: 890 million Western Cape reservoirs that city the feed were using more years. indrier rainy years and, like city’s the gardeners, not drawing allocation during full their the to one-thirdtled of region’s the water) were Cape’s wine and farmers fruit are (who enti the that missed They elsewhere. money the to delay big capital investments and spend recommendations.the were They happy supplies after 2015, but dismissed officials Cape Town’s to aneed boost flagged water ning inCape Town summer. this damin 2009,the helped to keep taps the run River Dam by six years. Eventually finished sition delayed completion the of Berg the and management of demand. Such oppo to switch to focus the water conservation environmentalists local when campaigned demand from urban and industrial growth. Supply System (WCWSS) to meet rising reservoirs to enable Western the Cape Water on and when where to tap sources and build managers,models. guided They for example, of responses such as restrictions. ofries users and evaluate effectiveness the risks of supply failures to different catego ment. Crucially, allow planners they to assess network as well as planning for develop support real-time operations of water the how much storage The is models needed. matched to projections of demand to assess probabledict stream are flows. Those then and historical use hydrological data to pre basins, reservoirs and transmission channels world-class. map They river between links by national the government, are considered watertheir management urbations have systems to used models guide approach populist andscience risk assessment towards amore to aturn away from management on based Cape Town’s problems are due in large part SHORT-SIGHTED pipes, pumps and environment. the ofa part systems the managed to be as are People’s and beliefs behaviour are as much morestill often due to management. poor extreme weather or warming to global are to uncertainties. the Shortages attributed to Limberg, wrote inApril last year that they cillor responsible for Xanthea water services, They defended their decisions. defended their The counThey The response was short-sighted. The 6 models in2009,the Back had already But dam building in 2000s, the stalled For the heeded two policymakers decades, Since 1980s,South the Africa’s major con 1 . 2 . These models, run models, run . These ------not comprehend and financial social the But models. Town’s Cape logical did leaders were risks These hydro inthe reflected were fortunately interrupted by awet 2004. years1970. Three in 2002, 2003 and dry 2005 before,occurred late inthe 1930sand from of what were they in2013. streamoped same inthe area were just 20% in 2017. In 2017, flows in a small, undevel 750 millimetres in 2016; and 700 millimetres in 2014;less than 500millimetres in2015; 1,250 millimetres in2013;900millimetres ment of two the largest dams, rainfall varied: weather station, which is to close catch the mountainous terrain. At Jonkershoek the to place and year to year across region’s the stream dramatically flows vary from place 2017.How is disputed.dry and dry Rainfall drought that might not come to pass”. fence billions of rand for possibility the of a “it because is not spell to practical ring- dry had not addressed risk the of such a severe ©

* Average for1981to2010 The totalamountofwater stored inthesixlargestreservoirs thatsupplyCapeTown felltonewlowseachyear. Lower thanaverage rainfall inSouthAfrica’sWestern Capeexacerbated water shortagesoverthepast3years. CAPE TOWN DROUGHT REGIONAL RESERVOIR LEVELS ANNUAL RAINFALL JULY 2016TO JUNE2017 Three years consecutive have dry Then worst the happened — a case very 2 Rainfall (%ofnormal*)

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A 2015 l l r i SOUTH AFRICA g h t s r e BOTSWANA s e r v e d . - - - 2016 12 JULY12 VOL 2018 | NATURE 559| |175 sites are cited to support climate-change catchments. Although data from outside a departure from normal variability inthe unpredictable”. Yet there is little of evidence reason that climate cycles have become so impact of climate change is probably the Western Cape, wrote that last October “the obvious target. Helen premier of Zille, the to blame, shift the with climate change an unnecessary. cheapbeen insurance, even ifit had proved year ininterest charges — that would have would have cost just 75 million rands per lion rands in infrastructure in 2013–14 byraised year. 26%this Yet, investing 1 bil Water for tariffs consumers have been randsSouth African (US$181million). ism — have come to more than 2.5billion and indirect costs such as adrop intour and jobs inagricultural losses production water revenue,water crisis — reduced implications of decisions. their Johannesburg Port Elizabeth Cape Town’s decision-makers have tried do now.They far, So direct costs of the LESOTHO 2017 water from runningout. since early2018prevented Reduced urbanconsumption Pretoria Durban AFRICA 2018 COMMENT - - COMMENT

implementing strong centralized systems such as China’s, improving cooperation between the various organizations involved might help7. Because rivers generally cross political boundaries, water management is often organized in ‘watersheds’ that can be distant from politicians and their citizens. Cape Town draws water from two rivers beyond its boundaries, each of which is managed by a different agency. Managing water in SWIEGERS/BLOOMBERG/GETTY WALDO ‘problem-sheds’ that encompass major water users and the geographical areas on which they depend would be a better approach8. As water needs grow and water systems evolve, more resources will need to be devoted to monitoring and modelling. Tech- nical guidance must be integrated into political processes. As a minimum, politicians need to know who is doing the modelling and what the recommendations are. They also need that information in a for- mat and language that empowers them to act appropriately. So hydrologists must col- Residents fill water containers at the Newlands natural-water spring in Cape Town in November 2017. laborate with experts from the social sciences and humanities, notably economics, policy theories, it was the three-year sequence of transfers because of a manifesto commit- and law, to develop water-management tools dry years that proved devastating. ment to regional allies5. In Australia, as in that decision-makers and the public can Yes, meteorological changes are expected Cape Town, environmental opposition to understand and use9. With greater involve- over coming decades. For Cape Town, most dams and desalination increased cities’ ment of other disciplines, it will be easier to climate models predict a decrease in rainfall vulnerabilities to a multi-year drought. ensure that appropriate social, economic and by 2050, although local impacts are uncer- China is a counter-example. It has man- environmental criteria are used when select- tain3. Stream flows are even less predictable, aged to keep water flowing in some of the ing technical options — to store water in a because they will be reduced by heat and arid- world’s largest and fastest-growing cities dam or to use energy for desalination, for ity but can be increased by more-frequent and through responsive government planning example. intense rainfall. Such trends and uncertainties and major infrastructure projects. These Finally, practitioners also need to moni- can be factored into models, although histori- include the Three Gorges Dam, which tor and model peoples’ behaviour. The long cal hydrology should still provide reliable per- controls flooding on the Yangtze river, and time scales over which decisions and inter- spectives for the next few decades. the South–North ventions need to happen must also be better A more-immediate challenge for Cape transfer, which has “As water needs understood. And the easy resort to simplistic Town is that the area that supplies the Western channelled water grow and water solutions to ‘use less water’ and ‘rely on natu- Cape water system is very small — less than from the Yangtze systems evolve, ral infrastructure’ must be resisted. 800 square kilometres. Local variations in to Beijing since more resources Cities must move from crisis responses climate, by themselves, call for a conservative 2015. The nation will need to to effective management of the water that and risk-averse approach, and the need for a has drawn some of be devoted to is essential to lives, livelihoods and environ- diverse range of water sources to fall back on. those lessons from monitoring and ments. ‘Day Zeros’ are not inevitable. ■ Now, Cape Town’s leaders are working South Africa. modelling.” feverishly to build the schemes that were In 2002, Wang Mike Muller is an engineer and visiting recommended back in 2009 for managing Shucheng, the Chinese minister charged adjunct professor at the Wits School groundwater, reuse and surface supply. The with resuscitating the transfer project, vis- of Governance at the University of the crisis has obliged them, and others else- ited the Lesotho Highlands Water Project. Witwatersrand in Johannesburg, South where in the country, to look more carefully This binational network of tunnels and dams Africa. at future challenges. The premier of Gauteng diverts water from the mountains of Lesotho e-mail: [email protected] province, the country’s inland urban hub, has to South Africa’s inland economic hub. Back 1. Muller, M. Civ. Eng. June, 11–16 (2017). convened a high-level task force to tell offi- in China, Wang got the sequence right. He 2. Basson, M. S. & Van Rooyen, J. A. J. Hydrol. 241, cials how to avoid Cape Town’s experience. completed the major engineering projects 53–61 (2001). 3. Abiodun, B. J. et al. Clim. Change 143, 399–413 needed to underpin supply while, in parallel, (2017). GLOBAL PROBLEM starting longer-term programmes to reduce 4. Escobar, H. Science 347, 812 (2015). São Paulo and Barcelona also had precedents pollution, manage demand and promote 5. Hernández-Mora, N., del Moral, L., La-Roca, 6 F., La Calle, A. & Schmidt, G. Interbasin water for their dry spells. And political decisions efficient water use . transfers in Spain: Interregional conflicts and exacerbated their water crises. São Paulo’s governance responses. In Globalized Water pp. drought risk was highlighted in hydrologi- POLITICAL PROCESS 175–194 (Springer, 2014). 6. Wang, S. Resource-oriented water management: cal models, but wrangling between city, state The greatest challenge for managers of Towards harmonious coexistence between Man and national governments delayed action urban water supplies is often getting political and Nature (China WaterPower, 2002). for a decade4. In Barcelona, a surprise 2004 decisions made in a timely fashion, and with 7. Woodhouse, P. & Muller, M. World Dev. 92, election win saw the Spanish Socialist public support. 225–241 (2017). 8. Mollinga, P. P., Meinzen-Dick, R. S. & Merrey, D. J. Workers’ Party (PSOE) stop a long-planned There is no universal best-practice Dev. Pol. Rev. 25, 699–719 (2007). programme of dam development and river approach to achieve this. Beyond 9. Fatichi, S. et al. J. Hydrol. 537, 45–60 (2016).