Classification of early warning levels for rainstorm disaster and its application in Anhui Province

Abstract

Based on the rainfall data at the81 national surface meteorological observation stations from 1961 to 2016 and the hourly rainfall data at the 1162 surface automatic weather stations over Anhui Province from 2006 to 2016, the casualty loss data from Anhui Civil Department from 1961 to 2016, and the disaster condition for the 227 rainstorm events collected in Anhui meteorological disaster Yearbook from 2006 to 2016, we have conducted a statistical analysis of the effect of the duration, region, area range, and daily and hourly rainfall for the rainstorm events on disaster loss by using several methods including climate average, generalized extreme, probability density function and percentile distribution, then accordingly classified the rainstorm disaster warning grades in Anhui Province. The main results are as follow. (1) The early warning of rainstorm disaster in Anhui can be divided into four levels, i.e., Ⅳ (mild), Ⅲ (moderate), Ⅱ (severe) and Ⅰ (extra heavy). (2) From levels Ⅳ to Ⅰ, the duration of rainstorm events ranges from 1 to 4 days, and their range is determined by the percentage of rainstorm area in total area of a region, increasing from 20% in level Ⅳ to 80% in levelⅠ. (3) According to the regional difference of rainstorm events, Anhui can be divided into the three areas, i.e., the northern Anhui along Huaihe River (Ⅰ), the Dabie Mountains and southern Anhui mountain regions (Ⅱ) and the region between Yangtze River and Huaihe River (Ⅲ). Then the quantitative relationship between the precipitation and the rainstorm disaster situation is established, and the corresponding daily and hourly rainfall indices are set up in each region. (4) Based on the above-mentioned early warning levels for rainstorm disaster, the149 rainstorm events causing disasters in Anhui from 1981 to 2018is constructed and tested, which is used in the early warning of rainstorm disaster from June to July in 2020. The results indicate that the release period of rainstorm disaster warning is around 0.66-0.82 years for level Ⅳ (mild), 15-1.90 years for level Ⅲ (moderate), 3.16-3.80 years for level Ⅱ (severe), and 9.5-12.6 years for level Ⅰ (extra heavy), which is consistent with the actual rainstorm disaster in Anhui and can provide a reference for the meteorological department to start the emergency response of rainstorm.

Keywords

• rainstorm disaster
• warning levels
• local standard
• emergency response