Elite consumptions trigger water shortages: Modelling heterogeneous interactions between drought and society

Cities face increasing droughts and water shortages as a result of extreme meteorological conditions and expanding human pressure. Future projections estimate that over one billion urban residents will experience severe droughts and water shortages in the near future. Most scientific and policy debates emphasize climate change, population growth and urbanization as the major forces at the genesis of this apocalyptic future. In this paper we argue instead that the root causes of urban water crises have to be retraced in the socioenvironmental injustices enmeshed with the development of a city. For it is not society as a whole that reshapes drought events or trigger water shortages. Usually, the most powerful groups with greater privileges and access to resources, are those who play a more prominent role in decisions on water resource use and allocation, thereby shaping the propagation of drought phenomena more significantly.  Accounting for the heterogeneity of human societies is thus key to understand the dynamics of human-water systems and, more specifically, the temporal and spatial propagation of drought phenomena. Sociohydrological models have not yet accounted for the manners in which heterogeneous social groups intersect with drought propagation. This work advances current analyses by modelling heterogenous interactions between human and water systems alongside their unequal influences on the transformation of drought into uneven water crises. The Day Zero crisis in Cape Town constitutes the empirical basis of this work. On the one hand Cape Town’s urban geography epitomizes an unequal landscape of water access and vulnerabilities. On the other hand, Day Zero exemplifies an extreme drought event that will most likely occur across many urban areas. Using a system-dynamic framework we retrace the uneven consumptions of water across Cape Town metropolitan area and estimate the drought resilience trajectories for different social groups. In turn, the socio-hydrological model explores the distinctive implication that each trajectory has for the sustainability of urban water systems. Ultimately, we argue that the unsustainable water uses of the elite can transform a meteorological drought into an urban water crisis.