From 2015 to 2017, the Western Cape province in South Africa suffered a severe drought, resulting in an extreme shortage of water resources in the city, making its capital, Cape Town, the first modern city in human history to face the threat of a “Day Zero” disaster (i.e., the day when the city’s water taps are turned off). However, the interaction mechanisms and processes of various disaster-causing factors remain unclear, and how to scientifically cope with the natural precipitation variation mode by man-made water-supply management needs to be further explored. Therefore, this paper explores the key stages, spatial distribution, and management benefits from the three dimensions of meteorological drought, hydrological drought, and urban water supply management. The results show the following:
The Western Cape experienced a significant increase in the area and intensity of meteorological drought from 2015 to 2017, with the most severe drought conditions occurring in May 2017. Compared with the Standardized Precipitation Index (SPI), the drought detected by Standardized Precipitation Evapotranspiration Index (SPEI) was more significant.
The hydrological drought conditions in the Western Cape in May 2017 were the most severe. This is broadly consistent with the pattern of spatial and temporal characteristics of meteorological drought, reflecting the rapid spread of meteorological-hydrological drought. Both the Standardized Runoff Index (SRI) results and the change in reservoir water volume reflect water scarcity in the region, indicating that the drought event had a serious impact on the Western Cape, which relies heavily on rainfall and reservoir water supply.
The Western Cape government adopted different levels of water restrictions and management policies in response to the evolution of this drought, effectively delaying and avoiding a “Day Zero” disaster; however, addressing the political and economic aspects of water inequality is still debatable and worth improving. This paper shows that urban drought problems involve multiple systems and interactions among the meteorology, hydrology, and water supply, and need to be monitored, understood, and mitigated in terms of the spatial and temporal processes.