Abstract: This article presents a flood simulation analysis using Storm Water Management Model (SWMM) to reduce water damage to the bridges and culverts of Lanzhou-Xinjiang Railway in the Gaotai overflow area and to determine the warning rainfall for some of these culverts. First, we construct two types of SWMMs, namely lumped and semi-distributed types, using the software ArcGis, and compare their pros and cons through calibration and accuracy evaluation for the simulations of six rainfall events. Then, the applicability of SWMM to the overflow area is discussed; finally, flood warning rainfalls are determined using a water level inversion method. The results show SWMM is applicable to the rainfall-runoff in this overflow area, with relative flood level errors less than 10% and a determination coefficient greater than 0.7. Of the six rainfall events, four are simulated with an accuracy reaching the level of Class A standard, and two reaching Class B, resulting in a qualification rate of 100%. Lumped hydrological models are better for application to the overflow area than the semi-distributed type. For a given disaster water level, a longer warning time means a greater warning rainfall.

Key words: overflow area, storm water management model, rainfall-runoff, hydrological model, warning rainfall