Core Viewpoint - The construction of a comprehensive seawater intrusion prevention and control system in Guangzhou represents a proactive shift in safeguarding water security in coastal megacities amid climate change challenges, including rising sea levels and extreme weather events [3]. Group 1: Monitoring and Data Collection - Guangzhou's planning and natural resources bureau has conducted a comprehensive survey of key coastal areas, covering nearly 1,400 square kilometers and over 300 kilometers of geophysical exploration, revealing the three-dimensional spatial distribution of freshwater and saltwater interfaces [5]. - The establishment of a monitoring network includes 60 new monitoring points and 114 layered monitoring wells, enabling hourly collection and remote transmission of key groundwater parameters [5]. Group 2: Risk Assessment and Early Warning - A dual-track early warning threshold system has been developed, categorizing risk levels by region, with high-level alerts for saline areas and sensitive alerts for freshwater protection zones [7]. - The system features an automatic triggering mechanism that promptly sends out warning information when key indicators exceed limits, enhancing the precision of risk management [7]. Group 3: Integrated Management and Decision Support - The creation of a "marine digital twin system" allows for high-precision three-dimensional hydrological models based on real-time monitoring data, facilitating a full-chain management mechanism from monitoring to decision-making [9]. - The integrated system combines intelligent perception, dynamic assessment, graded warnings, and coordinated responses, contributing to high-quality marine governance and sustainable urban development [9].