Hydrometric monitoring involves the measurement of hydrological components, i.e., the quantitative and qualitative assessment of standing and moving water through rainfall, at surface (e.g., lakes, rivers, and streams) and below ground. Traditional methods include various mechanical and analogue meters of water levels and flow velocity. But emerging hydrometric technology provides more accurate and higher resolution data, including the use of different acoustic, video, radar, and remote sensing (satellite and aerial) based methods. Equally important has been the integration of various hydrometric monitoring technologies, combined with real-time processing and interpretation of large datasets through complex numerical models, including recent artificial intelligence applications. These in turn are essential for improved water resource and flood risk management, environmental protection, and the planning of key infrastructure.