Statistical characteristics and risk zoning of different duration heavy rainfall in Shanxi

Abstract

Based on different duration heavy rainfall data and the associated disaster situation, geographic information, socio-economic characteristics, river network density, and geological hazard-prone zoning of 109 stations in Shanxi Province in the past 38 years, a statistical analysis of different duration heavy rainfall events in Shanxi Province was carried out. In addition, a comprehensive risk zoning was performed using hierarchy analysis and weighted comprehensive evaluation methods. The results show that: (1) the spatial distribution of the extreme value indicates the following: the mountain area is larger than that of the basin, and the south is greater than the north and has a shorter time-effect and a stronger local distribution of the extreme value. Yuanqu County (YuanQ) has the highest concentration area of all different duration heavy rainfall events within 12 h. (2) Within 12 h., the occurrence frequency of different duration heavy rainfall has the spatial distribution characteristics of being higher in the south and lower in the north, higher in the mountain area than in the basin area, higher in the eastern mountain area than in the western mountain area, and obviously concentrated in the southeast. YuanQ is a high incidence area of short-duration heavy rainfall over 1 h. and 3 h., and Jincheng City (JinC) is a high incidence area of heavy rainfall over 6 h and 12 h.. (3) Severe precipitation with different durations occurs in July–August every year, and the frequency of hourly heavy rainfall is the highest. (4) The intra-day distributions of heavy rainfall over a period of 1 h., 3 h., and 12 h. are single-peak curves, with peaks at 18:00, 19:00 and 09:00, respectively; the intra-day distribution of heavy rainfall over 6 h. is a double peak curve, with peaks at 06:00 and 20:00. (5) The variation trend of the annual occurrence times of short-duration heavy precipitation is similar for 1 h, 3 h, and 6 h, and the growth rate is the highest in southeastern Shanxi Province. The variation trend of the occurrence times of heavy rainfall over 12-h. is different from that of 1-h., 3-h., and 6-h. short-duration heavy rainfall. The rate of growth is the largest in the eastern and western mountain areas of Shanxi Province. (6) The whole area of JinC, the east of Yuncheng City (YunC), and the southeast of Changzhi City (CZ) are the high-risk areas for all different duration heavy precipitation disaster-causing factors within 12 h. As the duration of heavy rainfall increases, the high-risk areas with respect to disaster factors in Linfen City (LF) and CZ increase. (7) JinC, YunC, and Liulin County (LL) are high-risk areas for the comprehensive risk of different duration heavy rainfall within 12 h, and LF and CZ districts increase the extent of high-risk areas with the increase in the duration of heavy precipitation.