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Socio-hydrological drought impacts on urban water affordability

Nature Water volume 1, pages 83–94 (2023)Cite this article

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Abstract

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.

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Fig. 1: Schematic model overview and example model results.
Fig. 2: Stakeholder cost changes during droughts for given infrastructure, mitigation and drought scenarios.
Fig. 3: Cumulative changes in affordability during drought.
Fig. 4: Impact of price elasticity of demand on costs.
Fig. 5: Effects of infrastructure lock-in on cost increases.

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Data availability

All raw data used in this manuscript are freely available: hydrological scenarios derived from California Water Rights Databases62 (https://www.waterboards.ca.gov/waterrights/water_issues/programs/ewrims/), population and demographic data from IPUMS Microdata samples55, infrastructure scenarios from consulting reports45 and Urban Water Management Plans46 (https://wuedata.water.ca.gov/).

Code availability

The relevant code used for water system simulation and bill calculation is available from the corresponding author upon request.

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Acknowledgements

Funding for this work was provided by the Stanford Impact Labs (B.R. and S.F.) and the UPS Endowment Fund (B.R. and S.F.) at Stanford University. The funders had no role in study design, data collection and analysis, decision to publish or the preparation of the manuscript

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Authors and Affiliations

  1. Department of Civil and Environmental Engineering, Stanford University, Stanford, CA, USA

    Benjamin Rachunok & Sarah Fletcher

  2. Stanford Woods Institute for the Environment, Stanford University, Stanford, CA, USA

    Sarah Fletcher

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  1. Benjamin Rachunok
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B.R. and S.F. designed the research and developed the paper. B.R. and S.F. designed the modelling approach and B.R. developed the codebase and ran experiments. B.R and S.F. analysed the data and designed the visual elements of the paper. Both authors wrote and critically revised the manuscript.

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Correspondence to Benjamin Rachunok.

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Rachunok, B., Fletcher, S. Socio-hydrological drought impacts on urban water affordability. Nat Water 1, 83–94 (2023). https://doi.org/10.1038/s44221-022-00009-w

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