Effective and enhanced hydrological monitoring is essential for understanding water-related processes in a rapidly changing world. Image-based river monitoring, remote and proximal sensing, low-cost and opportunistic sensors, citizen science and artificial intelligence are reshaping the way hydrological processes are observed across scales, environments and conditions. Yet the value of these innovations depends on methodological rigour: new observational approaches need to be critically evaluated, benchmarked against established methods and integrated with existing datasets before their contribution to process understanding, modelling and operational hydrology can be established.

This session is co-sponsored by MOXXI (Measurements and Observations in the XXI century), the IAHS working group on novel observational methods, and provides a forum for research in which observation itself is the subject of investigation. We invite contributions on:

• Disruptive and Innovative sensors and technologies in hydrology (e.g., UAS, camera systems – RGB, thermal, multispectral and hyperspectral – low-cost and open-hardware sensors, distributed fibre-optic sensing).
• Advancing opportunistic sensing strategies in hydrology (e.g., commercial microwave links, GNSS reflectometry, smartphones, personal weather stations).
• Automated and semi-automated methods for extracting hydrological variables (e.g., water level, flow velocity, discharge, turbidity, plastic transport and river health parameters), including image processing, machine learning, data fusion, and edge-computing.
• Critical evaluation, benchmarking and intercomparison of observational approaches, datasets and products, including calibration/validation and uncertainty quantification.
• Integration of novel and conventional observations, and new approaches to long-term hydrological monitoring.
• Innovative citizen science and crowd-based methods for monitoring hydrological extremes.
• Novel strategies to enhance the detail and accuracy of observations in remote areas or data-scarce contexts.
• Demonstrations of how novel observations advance process understanding, model development and operational practice.•

The goal of this session is to bring together scientists advancing hydrological monitoring, to foster a critical discussion on the reliability and added value of emerging observational approaches, and to explore how these innovations can be scaled up to larger applications.