2026-03-10 スタンフォード大学
＜関連情報＞
- https://news.stanford.edu/stories/2026/03/new-research-shows-path-affordable-water-fast-growing-cities
- https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2025EF007976
新興インド巨大都市における干ばつによる水不足：政策評価のための結合型マルチエージェントシステムアプローチ Drought-Driven Water Insecurity in an Emerging Indian Megacity: A Coupled Multi-Agent Systems Approach for Policy Evaluation
Ankun Wang, Christian J. A. Klassert, Raphael Karutz, Mikhail Smilovic, Taher Kahil, Peter Burek, Yuanzao Zhu, Heinrich Zozmann, Bernd Klauer, Karin Küblböck, Ines Omann ,…
Earth’s Future Published: 05 March 2026
DOI:https://doi.org/10.1029/2025EF007976
Abstract
Developing regions face critical water security challenges driven by rapid urban growth, economic development, and climate change. In India, these issues are particularly evident in Pune, the country’s 9th most populated city. It is evolving into a sprawling urban agglomeration expected to grow from 7 to 11 million residents by mid-century. The city’s aging water-supply system is ill-equipped to ensure water access during droughts lasting 2–3 years, particularly for residents in informal settlements. We present a policy-evaluation model to assess options for addressing future urban freshwater insecurity. The model uses a coupled multi-agent systems approach that integrates human-environment interactions and responses to future drought, population, and economic conditions. Under business-as-usual for a mid-century, multi-year drought, major reservoirs dry up and groundwater levels decrease dramatically. The water use Gini coefficient exceeds 0.5, indicating severe inequality where most low-income individuals face: (a) unaffordable water costs (10%–18% of income), (b) vulnerability (<40 L daily), and (c) prolonged shortages (>6 continuous months). Comprehensive interventions, combining supply- and demand-side measures, cut the water use Gini coefficient in half and lower water costs by two-thirds. Implementing a strategic subset of interventions creates synergies that significantly enhance water security, yet remains insufficient for the low-income population. This study highlights how growing inequalities in urban water access exacerbate water security challenges, even under a suite of mitigating measures. In all scenarios, additional drought emergency supply will be required to address water insecurity of the lowest 10% income population.
Plain Language Summary
Prolonged droughts and increasing urban inequality create a growing risk of unprecedented water security challenges in emerging mega-cities. One such rapidly developing major urban agglomeration is Pune, India’s 9th largest city. Our research shows that the combined impacts of urbanization and a mid-century multi-year drought under climate change affect all Pune households, but hit hardest are the urban poor living in informal settlements. Through a novel coupled human-natural systems framework, we identify a mix of measures involving water reallocation, an agricultural-to-urban tanker water market, infrastructural improvements, and water regulations that effectively address water insecurity challenges. We further identify synergies that produce beneficial results with fewer implemented mitigating measures, providing guidance critical to policy makers and water managers.
