Water spectrum theory and technology: Supporting water security of National Water Network of China

The construction of the National Water Network of China (NWNC) is a major national initiative aimed at modernizing water governance and strengthening water security. However, the traditional understanding of water composition and dynamic evolution is not sufficient to support precision management and intelligent regulation of complex water systems. Here, we propose the water spectrum as a new concept and establish its scientific basis, conceptual framework, implementation pathway, and strategic role. The water spectrum is a framework organized around quantity, quality, and state (QQS), designed to support the construction of databases and spectral libraries for all elements of water across different water body types and management scenarios. Enabled by remote sensing, high‐throughput analysis, Internet of Things sensing, and artificial intelligence, it will support dynamic characterization, source tracing, forecasting, and risk identification. As the digital foundation and cognitive engine of the NWNC, the water spectrum will reshape the understanding of water cognition, support intelligent operation, and strengthen national water security.