Abstract: Urban flood disasters are a significant restraint on the sustainable development of society and economy; and many built-up areas have an urgent demand for upgrading the rainwater pipeline network in a limited space. This paper demonstrates local pipeline reconstruction, which improves the drainage capability of the whole area. A coupled hydrological and hydrodynamic model is developed, and pipeline reconstruction schemes are designed through identification of the waterlogging areas. Based on the return period of local flood control and drainage design, key factors of flood-waterlogging are examined, and flood risks are assessed using multi-source data before and after pipeline reconstruction. The results show that for the rainstorms with return periods of 3a and 30a, the reconstruction reduces the length of severely ill pipelines by 1990 m and 921.6 m and the node overflows by 73.61% and 55.13%, respectively. It lowers the rate of sub-healthy pipelines and improves the drainage capability of the pipeline network in the waterlogging areas; it reduces the area at the extremely dangerous flood level by 72.9% and the area at the highest comprehensive risk level by 17%. This study provides an optimal scheme for urban stormwater process control and flood risk reduction of the city. The comprehensive risk assessment helps its disaster prevention and mitigation planning and its response to emergencies.

Key words: flood control and drainage, multi-source data, flood-waterlogging simulation, process control, flood-waterlogging risk