Water is the source of life, the key to production, and the foundation of the ecosystem. United Nations Sustainable Development Goal (UN-SDG) 6 explicitly calls for ensuring the availability and sustainable management of water and sanitation for all, profoundly highlighting the core of water security and sustainable development in social progress and ecological health. However, the global water situation remains severe: currently, over 2 billion people live in water-stressed countries, and approximately 800 million people lack access to safe and clean drinking water. In China, about 30% of the land area is experiencing severe to extreme water scarcity, and nearly two-thirds of cities face varying degrees of water supply difficulties. Scientifically managing water resources, ensuring inclusive access to clean drinking water, and enhancing the resilience of water resource systems have become major strategic issues crucial to future development.

Global change is profoundly impacting the Earth system and the future of humanity in unprecedented ways. Extreme hydrological events such as basin rainstorms and floods, urban waterlogging, and widespread persistent droughts are becoming more frequent and intense. Rising sea levels not only exacerbate flood control pressures in coastal areas but also pose severe threats to river and coastal ecosystems. Faced with increasingly frequent extreme environments, the resilience and safety of critical infrastructure (such as dams, levees, urban water supply systems, and transportation networks) are facing brand-new tests. There is an urgent need to develop key technologies for the resilience and safety of critical infrastructure under extreme environments, enhancing their capacity to adapt, recover, and protect under extreme loads. At the same time, strengthening integrated basin management and improving overall system resilience to ensure water security and support high-quality economic and social development relies not only on innovations in water science and technology and improvements in institutional mechanisms but also requires us to proactively adjust our mindsets, lifestyles, and management models to better adapt to global changes and meet emerging challenges.

The International Conference on Water Security and Sustainable Development is an integral part of the "International Symposium on Strategic Development of Engineering Science and Technology" series by the Chinese Academy of Engineering. Co-initiated by the Nanjing Hydraulic Research Institute and Hohai University, it has been successfully held four times in 2015, 2017, 2021, and 2023. The forum has always been committed to breaking down disciplinary barriers, promoting collaborative innovation, facilitating international exchanges across geographical distances, and deepening top-tier global scientific research cooperation.

The 5th International Conference on Water Security and Sustainable Development, jointly hosted by the Nanjing Hydraulic Research Institute and Hohai University, will be held in Nanjing from October 18 to 21, 2026. This conference will focus on resilience and safety assurance for critical infrastructure in extreme environments, covering frontier topics such as extreme climate and water security, critical infrastructure and resilience enhancement, water network engineering and digital-intelligent operation and maintenance, digital twin water conservancy and artificial intelligence, and drinking water safety and health. We sincerely hope that this conference will serve as an important platform for open, candid, efficient, and interdisciplinary dialogue among scholars, scientists, policymakers, and practitioners in the field of water management. We cordially invite peers and professionals from around the world to participate in two days of in-depth discussions, bring diverse perspectives, spark intellectual exchange, and jointly contribute wisdom and strength to water security and sustainable development.