An operational basin-scale flood forecasting and dynamic risk analysis system: a case study from Sichuan Province, China

Since the launch of the national integrated natural disaster risk survey in 2022, followed by the flood risk mapping programme in 2025, an integrated basin-scale flood forecasting and risk analysis framework has been progressively developed to support operational flood warning and risk management in Sichuan Province. The framework integrates a multi-source refined database, basin-scale coupled hydrological–hydrodynamic models, and an operational dynamic flood simulation platform for major rivers.

At the data level, GIS and BIM technologies are integrated to construct L1–L3 refined three-dimensional databases for key basins, integrating fundamental geographic information, socio-economic and POI data, flood hazard investigation results, inundation extents for typical return periods, risk zoning products, as well as building distributions, oblique photography, BIM models, and near-real-time rainfall and hydrological observations. This results in a unified, updatable data foundation that supports operational flood simulation and loss assessment.

At the modelling level, an integrated basin-scale hydrological modelling system is coupled with one- and two-dimensional hydrodynamic models. By using meteorological forecasts as forcing, the system supports end-to-end simulation from forecast precipitation, through rainfall–runoff generation, to river flood routing, thereby enhancing temporal continuity and spatial accuracy for operational flood forecasting.

At the application level, an operational dynamic flood simulation and analysis platform has been developed for major rivers. Under operational conditions, the platform integrates real-time and forecast data to support multi-area and multi-scenario flood simulations, prediction of water levels and discharge at key cross-sections, and assessment of inundation extent and potential losses. The platform provides technical support for flood warning issuance, emergency evacuation, and risk management decision-making. It has been operationally deployed in the Minjiang, Dadu, Tuojiang, Fujiang, and Qujiang river basins, and is currently being extended to the Jialing and Qingyi river basins.