Flood forecasting in the Complex River Basin Affected by Man-made Hydraulic Structures

Flood forecasting is particularly challenging in complex basins influenced by man-made structures and regulations. To enhance forecasting accuracy, a coupled hydrological and 1D/2D hydrodynamic model was developed to simulate flood process in mountainous streams, plains river networks, hydraulic control structures and flood detention areas. Applied to the Puyang River Basin, a densely populated region characterized by hills and plains, the coupled model integrates Xin’anjiang model with Muskingum routing module to estimate upstream mountainous flow discharge, and employs 1D /2D hydrodynamic model to simulate flood processes in rivers and overland areas. This coupled framework, encompassing a 2,500 km² catchment area, includes 7 river branches, 7 dams, 1 flood detention area, and over 100 floodgates and pumps, incorporating real-time flood control operations. Calibration and validation with over 30 years of observed flood data demonstrates over 85% acceptability, confirming the model’s robustness and reliability. Therefore the coupled model become a feasible tool to monitor and forecasting flood process in a complex catchment with many regulated structures. However, comprehensive datasets, including long-term records of precipitation, evaporation, water level, and discharge, as well as detailed topographic and infrastructure data, are critical for accurate calibration and forecasting.

This approach facilitates real-time monitoring and prediction in complex, regulated basins. Discussions on flood scenarios considering disaster-inducing factors, flood control strategies, and optimized structural operations are addressed, providing a framework adaptable to other similarly complex river basins.