Abstract: As important drainage systems, underground pipe networks and water systems directly determine the flood safety in cities. In this study, 1D and 2D hydrological-hydrodynamic coupled numerical models are applied to simulate urban rainstorm of the Central Optical Valley in Wuhan, China in different schemes of factor combinations, such as with or without pipe networks, water system and so on. The abatement effects of urban underground pipe networks and planned water system construction on urban flood disasters are quantified. Results demonstrate that: in the absence of mature drainage system in the Central Optical Valley, the waterlogging scope, flooded area and disaster loss reach the maximum; in the presence of drainage system, the abatement rates of flooded area and disaster loss reach 56.58% and 63.74%, respectively. Due to different scopes and action modes, the effect of separate construction of water system on regional drainage is smaller than that of separate construction of underground pipe network. Among different land use types, the disaster reduction effect of residential land is the most sensitive to the construction of urban drainage system. When the water level of downstream lake is high, the lake has a backwater jacking effect on the water system. Such influence on urban flood disaster is related to river longitudinal slope, river embankment elevation, linkage between underground pipe networks and river channel.

Key words: drainage system, underground pipeline networks, urban flood disaster, abatement effect, lake level