Abstract:

Precipitation extremes are expected to become more frequent and intense under global warming in the coming decades. Risk analysis of precipitation extremes has become a hot issue in academic circles and governments. In this paper, we use the data recorded at 756 meteorological stations from 1951 to 2011. Data were first processed to generate a coherent set of precipitation datasets. Pearson-III frequency analysis method was used to define the thresholds of different rainfall return periods. We chose total extreme precipitation amount and extreme precipitation frequency as indices, and scenarios with return periods of 5, 10, 50 and 100 years were designed to analyze precipitation extremes. The vulnerability of economy and population to precipitation extremes was analyzed. Precipitation extremes and the associated vulnerability were evaluated using the risk assessment model of ISDR to assess the risk pattern of precipitation extremes in China, mapping the risk distribution of precipitation extremes under different return periods in China during the past 60 years (1951-2011). Results show that: (1) the magnitude of extreme precipitation decreases from the southeastern coastal areas to the northwestern inlands. The high-risk areas of extreme precipitation in the 5-year scenario are mainly located in southeastern coastal China. The boundary between high-risk and low-risk areas nearly coincides with the isohyet of 400 mm; (2) China's extreme precipitation is mainly observed in densely populated and economically developed eastern coastal metropolitan areas, especially in Yangtze River Delta urban agglomeration, Pearl River Delta urban agglomeration, Beijing-Tianjin-Hebei urban agglomeration and several large cities in the western region of China. The western region of the country, which is resource-scarce and economically less developed, is associated with lower-risk precipitation extremes; (3) under each return period, the extreme precipitation risk level decreases from southeastern coastal areas to northwestern inland areas. The high-risk level areas are distributed in South China, southeastern coastal China, middle and lower reaches of the Yangtze River, Huang-Huai-Hai Plain, Bohai Rim and Sichuan Basin. The areas with high risk are mainly distributed to the east of the Heihe-Tengchong Line (Hu Line), and the medium and low risk areas are located to the west of the Hu Line, which is roughly consistent with the Hu Line of population density distribution in China. This research presents a novel approach to evaluating national-scale precipitation extremes and the associated socio-economic risks. Findings obtained herein can be used as scientific references for governments at all levels in disaster prevention and reduction of extreme precipitation in China.

Key words: precipitation extremes, risk assessment, hazard analysis, vulnerability analysis, China