Analysis of Impacts of Extreme Precipitation in Kaizhou on Wanzhou-Dazhou Expressway Transportation

Abstract Based on the rainfall data of Kaizhou, the characteristics of extreme precipitation in Kaizhou from 1960 to 2016 and its influence on transportation are analyzed. The results show that, the number of rainy days was noticeably large before 1980s in Kaizhou, and the number of rainy days was more than 200d from 1973 to 1979. However, the number of rainy days decreased rapidly and basically kept stabile below 150d after 1980s. The threshold value of extreme precipitation events is 20mm in Kaizhou, and the annual average value of extreme precipitation events is 18d. The western Pacific subtropical high pressure extended westward in 2006, and inclined to the west and north, compared with the previous years. Besides, it was stable and maintained for a long time. These gave rise to severe drought in Chongqing in 2006 and further resulted in the decrease of extreme precipitation events in Kaizhou in 2006. There are 3 dangerous areas where weather influencing factor is extreme precipitation in Kaizhou section of Wanzhou-Dazhou Expressway, and they are located at S002 K9+593-K20, S002 K0-K9+593, and S002 K20-K30. Kaizhou section of Wanzhou-Dazhou expressway suffered 7 road closure controls due to extreme precipitation from 2011 to 2014. In 2014, 4 road closures were caused due to frequent extreme precipitation. Strengthening the forecast of extreme precipitation events can reduce occurrence frequency of traffic accidents and give play to the maximum effect of road transportation.