Benefit simulation of flood control project in Taihu Lake basin under extreme floods

Flood control benefit assessment is very important for flood control project investment decision-making and disaster mitigation countermeasures. A set of integrated models and methods related to flood control benefit assessment were established and applied to the Taihu Lake basin. The set of models includes hydrological analysis methods integrating rainfall production and plain rain calculation, a large-scale hydraulic model composed of a river network hydrodynamic model and a plain regional flood analysis model, and a comprehensive damage assessment model considering the social economy and inundation factors. In this study, the flood damage of the Taihu Lake basin was simulated under extreme flood conditions. In addition, predictions of the disaster reduction benefits of different flood control projects in response to the basin-scale extreme floods were carried out. The results show that direct economic damage would be 56.829 billion RMB under the 200-year return period rainfall of the 1999 type. The flood control benefits of 30% to 100% reinforced external power would be in the range of 2.669 billion RMB and 4.570 billion RMB, followed by the benefits of new polder building and Taipu River widening. However, the benefit was merely 65 million RMB when the pump capacity of polders was increased by 30%. Based on these research results, countermeasures and suggestions, such as adding drain pumping stations along the river and the coast, strengthening the scientific dispatching of polders, and coping with risks through insurance sharing, are proposed to provide support and serve as references for extreme flood prevention in the Taihu Lake basin.