Socio-hydrological drought impacts on urban water affordability

In water-stressed regions, droughts pose a critical challenge to urban water security for low-income households. Droughts reduce water availability, forcing water providers to invest in additional supplies or enact expensive, short-term emergency measures. These costs are frequently passed on to households through increased rates and surcharges, driving up water bills for low-income households and altering patterns of water consumption. Here we have developed a socio-hydrological modelling approach that integrates hydrology, water infrastructure, utility decision-making and household behaviour to understand the impacts of droughts on household water affordability. We present here an application based on Santa Cruz, California and show that many drought resilience strategies raise water bills for low-income households and lower them for high-income households. We also found that low-income households are most vulnerable to both changing drought characteristics and infrastructure lock-in. Unaffordable water prices pose a threat to human health and well-being. A socio-hydrological modelling approach that integrates hydrology, water infrastructure, utility decision-making and household behaviour can be used to understand the impacts of droughts on household water affordability