Abstract: Lanzhou Railway Bureau is a main personnel and material transportation artery in northwest China, and manages 5 main railways in the popedom of the bureau: the western section of the Longhai Railway, southern section of the Baotou-Lanzhou Railway, eastern section of Lanzhou-Xinjiang Railway, northern section of the Baozhong Railway and Gantangzi-Wuwei Railway and 10 branch lines. The railways in the popedom of the bureau pass through Gansu Province and Ningxia Hui Autonomous Region. In this area, weather and climate is diversity, rainfall is quite different from different regions, the geographical environment is complicated, there are the Gobi deserts, deserts, mountains, plateaus and other landforms, and flood disasters occur frequently along the railways. In this paper, the data of disrupted times and their durations of the railways as well as rainfall are used to discuss flood disasters along the railways within the popedom of Lanzhou Railway Bureau during the period from 2002 to 2007. The temporal variation of flood disasters along the railways and their relationship with precipitation are analyzed. Results show that the flood disasters along the railways varied with rainfall type and intensity for different railway sections. Flood disasters occurred mainly during the period from May to October, especially from July to August, and the proportions of disrupted times and their durations of the railways were 62% and 77% of the total flood disasters. The water-damaged railway sections were mainly distributed along 5 railways and increased from northwest to southeast, the regional feature of water-damaged railway sections was obvious, and flood disasters were the most serious along the railway sections from Lanzhou to Dingxi and then to Tianshui. In this 2 sections, the average annual disrupted times of the railways were 15 and 12, and the average annual disrupted durations of the railways were 40.8 and 20.8 hours, respectively. Flood disaster along the railways was closely related to precipitation. The correlation between the disrupted times of the railways and precipitation was 0.78, and the correlation between the disrupted duration of the railways and precipitation was 0.41. Regional heavy rainfall, severe convective weather and continuous rainfall were the main factors resulting in water damage of the railways. There were 85 flood disasters along the railways during the period from 2002 to 2007, in which 50.5% were caused by the severe convective weather, 42% by regional heavy rainfall, and 9.5% by autumn continuous rainfall.

Key words: railway, flood disaster, precipitation type, precipitation level, warning level, spatiotemporal distribution, meteorological condition, Lanzhou