Comprehensive Analysis of Flooding and Flooding Causing Precipitation Characteristics in Qinghai Province

Abstract

Using observed hourly precipitation data and disaster records of flooding in Qinghai， we adopt the ratio weight method to construct the disaster index of flood disaster events based on the direct economic loss， disaster-affected population， collapsed houses， agricultural economic loss and agricultural disaster area.According to the percentile method， flood disasters are graded into general， heavy， severe， and extra heavy.The disaster distribution characteristics and differences of the four ranks are analyzed and compared with the precipitation characteristics in Qinghai.Principal component analysis， box-whisker plot and correlation analysis are employed to investigate the main factors that lead to flood disasters in Qinghai and the differences among regions.Results show that flood disasters occur frequently， and losses caused by floods increase.The frequency of severe and extra heavy disasters increases significantly after 2016， and the periods of July and August are the most frequent periods of flood disasters in Qinghai every year.The eastern part of Qinghai is an area of frequent floods and the most serious disasters.The Hainan Prefecture has the most flooding frequency and the Haidong City suffers the most serious disaster losses.The flooding disasters in Qinghai are mainly induced by rainfall processes that are more serious than heavy rainfall.The process of flood-causing precipitation in Qinghai can divide into two categories， one is short-lived but has a high rainfall intensity， which has a rainfall duration of 12 h and can cause high accumulated precipitation.The other can also induce high accumulated precipitation， and its rainfall duration is generally longer than 12 h.The flood disasters occurring in eastern cities like Hainan， Huangnan， Haibei， Xining and Haidong are mainly induced by the first category of precipitation process mentioned above.The second category of rainfall process is mainly found in Haixi and Yushu Prefecture， and Huangnan， Haibei， Xining and Haidong are also affected by this precipitation process.The accumulated precipitation and 24 h precipitation are closely associated with flood disaster losses， and longer precipitation duration can further aggravate flood disaster losses.

Keywords

• flood disasters
• flooding causing precipitation
• disaster index
• precipitation factors