Background  Yunnan province is a storm-prone region. Due to the climatic and complex geographical environment, characteristics of rainstorm are various a lot in different regions. A study of the characteristics of the rainstorm in small region is helpful for the prevention of rainstorm damages. The lower reach of the Honghe River is located at Honghe region where rainstorms occur frequently. In addition, it is easy to cause flooding, landslides and debris flows and other geological disasters when amount of daily rainfall is over 25 mm. Hekou county is located in the lower reach of the Honghe River and is one of the six major rainstorm centers in Yunnan. This paper takes Hekou county as an example to study the characteristics of rainstorm types in this region.

Methods  Based on 177 rainstorms occurring in this region, K-means clustering was used to study type, characteristics and risk of rainstorms in Hekou county.

Results  The results show that the rainstorm is obviously seasonal, mainly from April to September, and dominated by P₂₄ in Hekou county. The types of rainstorms in Hekou county can be divided into four which are the previous rainfall (Ⅰ) type, medium-term rainfall (Ⅱ) type, late-rainfall (Ⅲ) type, and even rainfall (Ⅳ) type. The type Ⅰ accounts for more than 2/3 of the total rainstorm and is the main type of rainstorm in this area. 80% precipitation of rainstorm and the larger value of average rainfall intensity generally occur within the first 0.4 cumulative rainfall duration, the first 4 hours in a day. Since this type rainstorm will cause very serious damage, it should be paid highly attention to; According to the national grade of rainstorm warning, the rainstorms are dominated by orange and yellow warnings, which accounting for 42% and 32% of the total number of rainstorm warnings respectively. In this case, the risk of hazard level is higher, which may cause mountain torrents and mudslides in Hekou county. The warning and control measures of rainstorm should be made in advance.

Conclusions  This study discusses the characteristics of rainstorm in Hekou county, clarifies the types of rainstorm and duration, rainfall precipitation, rainfall intensity, warning level of each type, which are helpful to the prevention of rainstorm damages in this region.