The question of balancing the competing uses of prior and late developers has long been the core issue in international water law (IWL). Yet, how IWL evolves to assure the flexibility and continuing adaptability of its norms in the context of changing circumstances of water use regimes, has not been the subject of comprehensive academic research. Based on an empirical analysis of 459 international water treaties, this research reveals that equal protection of prior use and later use is becoming an emerging trend for international treaty practices, while obligations of “due diligence” emerge to redefine the “no-harm” principle; the growing concern for environmental protection challenges the basic understanding of the concepts of “harm” and “reasonableness”. To strengthen the trend for equal protection and to ensure greater flexibility and adaptability of IWL, this paper focuses on the promotion of institutional water cooperation, the forging of common understanding over the importance of transboundary environmental protection, and the development of more up-to-date global legal frameworks.

平衡先发者和后发者的竞争用途的问题长期以来一直是国际水法 (IWL) 的核心问题。然而，IWL 如何发展以确保其规范在用水制度不断变化的情况下的灵活性和持续适应性，尚未成为综合学术研究的主题。本研究基于对459个国际水条约的实证分析，发现先用后用平等保护正在成为国际条约实践的新趋势，而“尽职调查”义务的出现重新定义了“无害”原则; 对环境保护的日益关注挑战了对“危害”和“合理性”概念的基本理解。